Invest Clin 65(4): 426 - 435, 2024 https://doi.org/10.54817/IC.v65n4a03

Corresponding authors: Ting Wang & Yuqin Wu. Ward of Special Needs, Kunming Children’s Hospital, Kunming

650103, Yunnan Province, China. Email: wangtingkch@ltyz-edu.cn; qudas0@163.com

Correlations of serum 25-hydroxy-vitamin D,

CD4+CD25+CD127– regulatory T cells

and total immunoglobulin E in children

with recurrent respiratory tract infections.

Yanfei Yang, Na Fan, Xingzhu Liu, Lin Wang, Zhihai Wang, Yao Hou,

Ting Wang and Yuqin Wu

Ward of Special Needs, Kunming Children’s Hospital. Yunnan Province, China.

Keywords: cluster of differentiation; correlation; 25-hydroxy-vitamin D;

immunoglobulin; recurrent respiratory tract infection; regulatory T cell.

Abstract. Recurrent respiratory tract infections (RRTIs) have a complex

pathogenic mechanism. There may be correlations between expression levels of

serum 25-hydroxy-vitamin D (25-OH-D), regulatory T cells (Tregs), total immu-

noglobulin E (IgE) and RRTIs. We aimed to explore the correlations of serum

25-OH-D, cluster of differentiation 4 (CD4)+CD25+CD127- Tregs and total IgE

in children with RRTIs. A total of 150 children with pneumonia were enrolled

as the subjects and randomly assigned into a control group (97 children with

non-RRTIs) and an observation group (53 children with RRTIs). The expression

levels of serum 25-OH-D, CD4+CD25+CD127- Tregs and total IgE were compared

in RRTI children with different genders, stages, sites of lesions and severities

of illness. The correlation was tested by Pearson analysis. The expression level

of serum 25-OH-D was significantly higher in children with RRTIs in the upper

respiratory tract than that in the lower respiratory tract, whereas the expression

level of total IgE was significantly lower in children with RRTIs in the upper re-

spiratory tract (p<0.05). The expression level of 25-OH-D was negatively corre-

lated with expression levels of CD4+CD25+CD127- Tregs and total IgE (r=-0.355,

-0.314, p<0.05), while a positive correlation was found between expression levels

of CD4+CD25+CD127- Treg and total IgE (r=0.237, p<0.05). The area under the

curve of combination of 25-OH-D, CD4+CD25+CD127- Treg and total IgE expres-

sion levels for predicting RRTIs was 0.852. The combined detection of the three

indicators is conducive to enhancing the detection rate of RRTIs.

Detection of recurrent respiratory tract infections 427

Vol. 65(4): 426 - 435, 2024

Las correlaciones séricas de 25-hidroxivitamina D,

CD4+CD25+CD127– linfocitos T reguladores e inmunoglobulina

E total en niños con infecciones recurrentes del tracto

respiratorio.

Invest Clin 2024; 65 (4): 426 – 435

Palabras clave: cluster of differentiation; correlacion; 25-hidroxi-vitamina D;

inmunoglobulina; infeccion recurrente del tracto respiratorio,

T cell reguladora.

Resumen. Las infecciones recurrentes del tracto respiratorio (ITRR)

tienen un mecanismo patogénico complejo. Puede haber correlaciones entre

los niveles de expresión de 25-hidroxivitamina D (25-OH-D) sérica, células T

reguladoras (Treg), inmunoglobulina E total (IgE) y RRTI. Nuestro objetivo

fue explorar las correlaciones de la 25-OH-D sérica, el grupo de diferenciación

4 (CD4)+CD25+CD127– Tregs y la IgE total en niños con IRRR. Se inscribió

un total de 150 niños con neumonía como sujetos y se los asignó aleatoria-

mente a un grupo de control (97 niños sin RRTI) y un grupo de observación

(53 niños con RRTI). Se compararon los niveles de expresión de 25-OH-D,

(CD4)+CD25+CD127– Tregs en suero y de IgE total en niños con RRTI con di-

ferentes géneros, estadios, sitios de lesiones y gravedad de la enfermedad. La

correlación fue probada mediante análisis de Pearson. El nivel de expresión de

25-OH-D sérico fue significativamente mayor en niños con IRRI en el tracto

respiratorio superior que en el tracto respiratorio inferior, mientras que el nivel

de expresión de IgE total fue significativamente menor en niños con IRRI en el

tracto respiratorio superior (p<0,05). El nivel de expresión de 25-OH-D se co-

rrelacionó negativamente con los niveles de expresión de (CD4)+CD25+CD127-

Tregs y la IgE total (r=-0,355, -0,314, p<0,05), mientras que se encontró una

correlación positiva entre los niveles de expresión de (CD4)+CD25+CD127–

Treg e IgE total (r=0,237, p<0,05). El área bajo la curva de combinación de

los niveles de expresión de 25-OH-D, (CD4)+CD25+CD127- Treg y de IgE total

para predecir IRRI fue de 0,852. La detección combinada de los tres indicado-

res conduce a mejorar la tasa de detección de IRRI.

Received: 09-04-2024 Accepted: 25-08-2024

INTRODUCTION

Recurrent respiratory tract infections

(RRTIs) possess a relatively complex patho-

genic mechanism, which involves various

pathogenic factors. Children are susceptible

to RRTIs, with a major age of onset of 2-6

years old, and in terms of the prevalence

rate, children with RRTIs account for ap-

proximately 20.00% of children with respi-

ratory infections 1,2. The incidence rate of

RRTIs is about 16.80-18.70% in children in

China, and 80.00% of children with RRTIs

are aged below 5 years old 3. 25-hydroxy-

vitamin D (25-OH-D) is mainly metabolized

by vitamin D-25-hydroxylase. Studies have

manifested that 25-OH-D is implicated in

the development and progression of RRTIs,

428 Yang et al.

Investigación Clínica 65(4): 2024

exerting a profound impact on the body im-

munity of developing children 4,5. Regula-

tory T cells (Tregs), a common subset of T

cells, control the autoimmune response of

the body. Animal experiments have revealed

that the content of Tregs [cluster of differ-

entiation 4 (CD4)+CD25+ Forkhead box P3

(Foxp3) Tregs] is higher in RRTI mice than

that in normal mice, but it declines signifi-

cantly after drug intervention 6,7. Generally,

immunoglobulin E (IgE) is mainly produced

in plasma cells of the respiratory and di-

gestive tracts, which has an extremely low

expression level in blood of normal people

(about 0.002% of total Ig in serum), and its

abnormal expression is related to the devel-

opment and progression of some diseases,

including RRTIs.8 Based on the above analy-

sis, it can be concluded that there are cer-

tain correlations between expression levels

of serum 25-OH-D, Tregs and total IgE and

RRTIs.Kunming is situated in the Yunnan-

Guizhou Plateau, China, where the incidence

of RRTIs may be of specific characteristics.

In addition, research on the relationship be-

tween RRTIs and expressions of 25-OH-D,

CD4+CD25+CD127- Tregs and total IgE is

lacking (or rare) at present, so it is neces-

sary to carry out such research. In this study,

therefore, the expression levels and relation-

ships of 25-OH-D, CD4+CD25+CD127- Tregs

and total IgE were explored with 150 chil-

dren with pneumonia (including 53 children

with RRTIs) as the subjects, aiming to pro-

vide a basis for clinical diagnosis and treat-

ment of children with RRTIs in the plateau

section.

PATIENTS AND METHODS

General data

According to the guidelines of the Dec-

laration of Helsinki, the study was performed

with approvals from the medical ethics com-

mittee of our hospital. One hundred and

fifty children with pneumonia admitted to

and treated in Kunming Children’s Hospital,

China from January 2020 to January 2023

were selected as the subjects. The children

were assigned into a control group (97 chil-

dren with non-RRTIs) and an observation

group (53 children with RRTIs) using a ran-

dom number table.

The inclusion criteria for the observa-

tion group were set as follows: 1) children

aged 0-12 years old, without gender require-

ment, 2) those who were diagnosed with

pneumonia and met the diagnostic criteria

for RRTIs, 3) those who lived in the jurisdic-

tion of Kunming, China and 4) those whose

family members and caregivers had signed

the informed consent and who were willing

to participate in this study. The inclusion

criteria for the control group were as fol-

lows: 1) children aged 0-12 years old, with-

out gender requirement, 2) those who were

diagnosed with pneumonia and did not meet

the diagnostic criteria for RRTIs, 3) those

who lived in the jurisdiction of Kunming,

China, and 4) those whose family members

and caregivers had signed the informed con-

sent and who were willing to participate in

this study.

The exclusion criteria involved: 1) chil-

dren with all kinds of congenital diseases,

cancers (liver, lung, brain, pancreas, thyroid,

etc.) or severe deformities, 2) those with var-

ious hematological, immunological or mo-

tor disorders, 3) those with airway obstruc-

tion, external tracheal compression, asthma,

bronchiectasis or foreign bodies in the bron-

chus, 4) those with abnormal diet (including

those with various nutritional diseases), 5)

those who had taken immunosuppressants

within 3 months before enrollment, 6) those

with hereditary or metabolic diseases, 7)

those with anemia or obesity (BMI>P95), or

8) those whose family members and caregiv-

ers were not informed or had not signed the

informed consent or who had incomplete

clinical data.

The control group was composed of 97

patients, including 61 (62.89%) boys and 36

(37.11%) girls, aged 0-12 (4.12±1.25) years

old. As to severity of illness, there were 51

mild cases, 24 moderate cases and 22 se-

Detection of recurrent respiratory tract infections 429

Vol. 65(4): 426 - 435, 2024

vere cases. The observation group consisted

of 53 patients, including 33 (62.26%) boys

and 20 (37.74%) girls, with an age of 0-12

(4.23±1.27) years old. In terms of severity of

illness, there were 27 mild cases, 16 moder-

ate cases and 10 severe cases, respectively. As

to the site of lesions, there were 34 and 19

cases of upper and lower respiratory tract in-

fections, respectively. The general data such

as age, gender and severity of illness were of

no significant differences between the two

groups (p>0.05), which were comparable.

Detection methods

After admission, the demographic data

(age, gender, etc.) of patients were collected

in both groups. The next morning, an appro-

priate amount (5 mL) of venous blood was

collected from the elbow of each child in the

company of their family members and care-

givers. Then, the blood was centrifuged with

a centrifuge (Beckman Coulter, USA, Optima

MAX -TL) under the following conditions:

centrifugal radius of 15 cm, centrifugal rate

of 2000 rpm and centrifugal time of 5 min.

Afterwards, the serum was harvested for mea-

surement of 25-OH-D, CD4+CD25+CD127-

Treg and total IgE expression levels. The

expression level of 25-OH-D was detected

by magnetic microparticle chemilumines-

cence assay, while the expression levels of

CD4+CD25+CD127- Tregs and total IgE were

measured by a flow cytometer and an auto-

matic protein analyzer, respectively. The mea-

surement was conducted strictly according

to the specific standard operating procedures

for detecting 25-OH-D, CD4+CD25+CD127-

Tregs and total IgE 9.

The expressions of serum 25-OH-D,

Tregs and total IgE in observation and con-

trol groups were measured and compared.

Additionally, the expressions of serum 25-

OH-D, CD4+CD25+CD127- Tregs and total

IgE in the observation group at different

stages (remission stage and attack stage),

genders (boy and girl), sites of lesions (up-

per and lower respiratory tracts) and severi-

ties of illness (mild, moderate and severe)

were measured and compared.

Statistical analysis

An Excel database was created, in which

the baseline data and research data of all sub-

jects were classified, numbered and counted.

Next, such data were included in SPSS 23.0

software for processing. Count data were

subjected to the χ2 test and expressed as rate

or percentage (%). Measurement data were

expressed by mean ± standard deviation and

subjected to the t test, and analysis of vari-

ance was employed for pairwise comparison

of means of three samples. The correlation

was tested by Pearson analysis. Receiver op-

erating characteristic (ROC) curves were

plotted, based on which the areas under

ROC curves (AUCs) were calculated to ana-

lyze the predictive values of expression levels

of 25-OH-D, CD4+CD25+CD127- Tregs and

total IgE for the incidence of RRTIs. The

value of AUC was between 0 and 1, where 1

represented a perfect classification and 0.5

represented random guessing. The best clas-

sification threshold was selected based on

the ROC curve. At the selected optimal cut-

off value, the corresponding sensitivity (true

positive rate) and specificity (true negative

rate) were calculated. At the selected cutoff

value, the false positive rate (1-specificity)

and false negative rate (1-sensitivity) were

calculated. The significant level was set as

α=0.05 (bilateral), and p<0.05 denoted that

the difference was statistically significant.

RESULTS

Expression levels of serum 25-OH-D,

CD4+CD25+CD127- Tregs and total IgE in

the two groups

The expression level of serum 25-OH-D

in the observation group was significantly

lower than that in the control group, whereas

the expression levels of CD4+CD25+CD127-

Tregs and total IgE were significantly higher

than those in the control group (p<0.05)

(Table 1).

430 Yang et al.

Investigación Clínica 65(4): 2024

Expression levels of 25-OH-D,

CD4+CD25+CD127- Tregs and total IgE

in children with RRTIs at different stages

in the observation group

Children with RRTIs at remission stage

in the observation group had a significant-

ly lower expression level of serum 25-OH-D

and significantly higher expression levels of

CD4+CD25+CD127- Tregs and total IgE than

those of the control group (p<0.05) (Table 2).

Expression levels of 25-OH-D,

CD4+CD25+CD127- Tregs and total IgE in

RRTI boys and girls in the observation group

In comparison with RRTI girls, RRTI boys

exhibited comparable expression levels of se-

rum 25-OH-D and CD4+CD25+CD127- Tregs

(p>0.05), but a slightly elevated expression

level of total IgE (p<0.05) (Table 3).

Expression levels of 25-OH-D,

CD4+CD25+CD127- Tregs and total IgE

in children with different severities

of RRTIs in the observation group

A lower expression level of serum

25-OH-D and higher expression levels of

CD4+CD25+CD127- Tregs and total IgE were

detected in children with severe RRTIs com-

pared to those in children with mild and

moderate RRTIs (p<0.05) (Table 4).

Expression levels of 25-OH-D,

CD4+CD25+CD127- Tregs and total IgE in

children with RRTIs in the upper and lower

respiratory tracts in the observation group

The expression level of serum 25-OH-D

in children with RRTIs in the upper respira-

tory tract was significantly higher than that

in the lower respiratory tract, and the ex-

Table 2

Expression levels of 25-OH-D, CD4+CD25+CD127- Tregs and total IgE in children with RRTIs

at different stages in the observation group.

Stage n25-OH-D (ng/mL) CD4+CD25+CD127-Treg (%) Total IgE (U/mL)

Remission 53 22.31±2.25 4.48±1.34 98.67±12.33

Attack 53 15.64±2.17 6.81±1.55 233.61±19.55

t15.534 8.279 42.502

p<0.05 <0.05 <0.05

Table 3

Expression levels of 25-OH-D, CD4+CD25+CD127- Tregs and total IgE in RRTI boys

and girls in the observation group.

Gender n25-OH-D (ng/mL) CD4+CD25+CD127-Treg (%) Total IgE (U/mL)

Girl 20 15.57±2.26 6.25±1.37 232.51±19.82

Boy 33 15.82±2.23 6.72±1.43 234.57±20.59

t0.573 1.728 2.045

p0.568 0.087 0.043

Table 1

Expression levels of serum 25-OH-D, CD4+CD25+CD127- Tregs and total IgE in the two groups

Group n25-OH-D (ng/mL) CD4+CD25+CD127-Treg (%) Total IgE (U/mL)

Control 97 25.34±3.68 4.87±1.32 81.62±10.28

Observation 53 15.58±2.27 7.15±1.84 233.17±18.62

t17.554 8.864 64.305

p<0.05 <0.05 <0.05

Detection of recurrent respiratory tract infections 431

Vol. 65(4): 426 - 435, 2024

pression level of total IgE was significantly

lower than that in the lower respiratory tract

(p<0.05) (Table 5).

Results of correlation analysis

The results of Pearson correlation anal-

ysis revealed negative correlations of the ex-

pression level of serum 25-OH-D with the ex-

pression levels of CD4+CD25+CD127- Tregs

and total IgE (r=-0.355, -0.314, p<0.05)

and a positive correlation between expres-

sion levels of CD4+CD25+CD127- Tregs and

total IgE (r=0.233, p<0.05) (Fig. 1).

Analysis results of predictive value

The AUC value of combination of 25-

OH-D, CD4+CD25+CD127- Tregs and total

IgE for predicting the incidence of RRTIs

was 0.852, which was significantly larger

than that of any of the three indicators

alone (0.752, 0.654 and 0.643, respectively;

p<0.05) (Fig. 2).

DISCUSSION

The expression level of 25-OH-D in chil-

dren with RRTIs (0.5 months to 14 years old)

is lower than that in healthy children (con-

trol group), and the insufficiency or deficien-

cy of vitamin D is related to the occurrence

of RRTIs 4. The lack of serum 25-(OH)-D3 in

children with RRTIs is an important reason

for the decreased expression level of plasma

LL-37 (one of the Cathelicidin antimicrobial

peptides) 10. This suggests that RRTI chil-

dren have obvious vitamin D deficiency or

deficit. In this study, the expression level of

25-OH-D in children with RRTIs was abnor-

mal, which was significantly decreased com-

pared with that in the control group (chil-

dren with non-RRTIs). Such a decrease in

the expression level of serum 25-OH-D may

be ascribed to the following factors. Firstly,

the immunomodulatory function of vitamin

D is related to the expression of vitamin D

Table 4

Expression levels of 25-OH-D, CD4+CD25+CD127- Tregs and total IgE in children with

different severities of RRTIs in the observation group.

Severity n25-OH-D (ng/mL) CD4+CD25+CD127-Treg (%) Total IgE (U/mL)

Mild 27 15.57±2.26 4.15±1.02 201.33±16.55

Moderate 16 15.82±2.23 5.84±1.23a** 239.75±20.58a**

Severe 10 13.08±1.85b**c* 6.89±1.52b**c 292.61±23.57b**c**

F5.75 22.99 84.11

p0.057 0.0000 0.0000

q test (Newman-Keuls method) for pairwise comparison of sample means (3), a: the first vs. the second, b: the first

vs. the third, c: the second vs. the third. *p<0.05, **p<0.01.

Table 5

Expression levels of 25-OH-D, CD4+CD25+CD127- Tregs and total IgE in children with RRTIs

in the upper and lower respiratory tracts in the observation group.

Site n25-OH-D (ng/mL) CD4+CD25+CD127- Treg (%) Total IgE (U/mL)

Upper respiratory tract 34 16.23±2.58 6.12±1.25 226.87±17.88

Lower respiratory tract 19 13.34±2.27 6.58±1.33 250.64±23.58

t 6.122 1.835 5.848

p <0.05 0.069 <0.05

432 Yang et al.

Investigación Clínica 65(4): 2024

receptors (in vascular endothelium, myocar-

dium, skeletal muscle, immune cells, etc.).

Vitamin D receptors have been confirmed to

have no expression in resting T lymphocytes.

However, when the body is infected, T lym-

phocytes are activated and can participate

in the mediation of 25-OH-D by expressing

cytochrome P450 family member 27B1, and

make it transform into 1,25(OH)2D. On this

condition, the endogenous nature of vitamin

D receptors is activated by stimuli, followed

by combination (vitamin D and its recep-

tors) and joint action to promote immune

cells to produce corresponding cytokines,

playing the role of immune regulation. As

a result, body immunity is enhanced 11,12.

Secondly, 25-OH-D can interact with macro-

phages and monocytes, producing tubulins

and defensins with antibacterial and antivi-

ral activities in the induction period, thus

affecting the phagocytic ability and chemo-

taxis of macrophages and monocytes, and en-

hancing the differentiation of monocytes to

macrophages 13. It follows that the decrease

in the expression level of serum 25-OH-D in

children with RRTIs is related to insufficient

intake of vitamin D and repressed expression

of vitamin D receptors.

Tregs impede the activation and prolif-

eration of target cells inhibiting the expres-

sion of CD25 (interleukin-2 receptor sub-

unit alpha, IL-2Ra) chain on the surface of

target cells. Second, Tregs suppress the pro-

liferation of effector cells and immunocom-

petence 14, i.e. Tregs secrete such inhibitory

cytokines as IL-10 and transforming growth

factor-β to participate in immune suppres-

sion of the body. In this study, the expres-

sion level of CD4+CD25+CD127- Tregs in

children with RRTIs was subjected to a con-

trol study from the perspectives of disease

stage, gender, site of lesions and severity of

illness. It was found that the expression level

of CD4+CD25+CD127- Tregs in children with

RRTIs was abnormal, which was significantly

higher than that in the control group (chil-

dren with non-RRTIs), implying that the devel-

opment and progression of RRTIs in children

Fig. 1. Correlation analysis results of 25-OH-D, CD4+CD25+CD127- Tregs and total IgE levels.

Fig. 2. ROC curves of predictive values of

CD4+CD25+CD127- Tregs and total

IgE for the incidence of RRTIs.

Sensitivity

1-specificity

Detection of recurrent respiratory tract infections 433

Vol. 65(4): 426 - 435, 2024

are influenced by CD4+CD25+CD127- Tregs.

Schenck et al. found that the expression

level of lymphocytes (CD3, CD4) in RRTI

children was lower than that in the con-

trol group (healthy children) 15. Moreover,

CD4+CD25+CD127- Tregs can effectively in-

hibit the immune response mediated by CD4+

and CD8+ effector cells16,17. This shows that

CD4+CD25+CD127- Tregs exhibit abnormal

proliferation and activation in RRTI children,

giving rise to enhanced response advantage of

Tregs, breaking the balance between T helper

type 1 (Th1)/Th2/Th17 cell system and Treg

cell system, and leading to the disorder of im-

mune regulation. Eventually, RRTIs develop

and progress.

In this study, the expression level of to-

tal IgE in children with RRTIs was compared

from disease stage, gender, site of lesions

and severity of illness. The results showed

that the expression level of total IgE in chil-

dren with RRTIs was abnormal and higher

than that in the control group (children

with non-RRTIs), signifying that the abnor-

mal expression of total IgE is related to the

development and progression of RRTIs. This

is attributed to the fact that repeated respi-

ratory infections affect the antigens, leading

to the exhaustion of the immune system and

increasing the expression level of total IgE

in serum.

The results of Pearson correlation

analysis uncovered that the expression

level of serum 25-OH-D was negatively

correlated with the expression levels of

CD4+CD25+CD127- Tregs and total IgE

(r=-0.355, -0.314), while the expression

level of CD4+CD25+CD127- Tregs was pos-

itively correlated with that of total IgE

(r=0.237). This demonstrates that the de-

velopment and progression of RRTIs is a

comprehensive pathological process, which

may be caused by the interaction of serum

25-OH-D, CD4+CD25+CD127- Tregs and

total IgE. It has previously been reported

that the children with RRTIs (196 children

aged 1 to 18 years old) had reduced serum

25-OH-D expression levels (61.00%), and

vitamin D expression level was negatively

correlated with age 18. In this state, the ex-

pression levels of immunoglobulins (IgA,

IgG) in children with RRTIs also decrease

19. In this study, when the expression level

of serum 25-OH-D in children with RRTIs

dropped, that of total IgE rose, i.e., there

was a negative correlation between the

two. It suggests that serum 25-OH-D may

be involved in mediation of humoral im-

munity. Beale et al. proved that the sever-

ity of RRTIs was correlated with the level

of vitamin D, and in RRTI children with a

low immune level, the serum 25-OH-D level

showed a positive relationship with the se-

verity of RRTIs 20. Hatam et al. confirmed

that CD4+CD25+CD127- Tregs were abnor-

mally expressed in children with RTTIs,

which was an important pathogenesis of

RRTIs.21 It can be concluded that serum 25-

OH-D, CD4+CD25+CD127- Tregs and total

IgE may participate in the development and

progression of RRTIs through interaction.

Moreover, it was also found in this study

that the AUC value of combination of 25-

OH-D, CD4+CD25+CD127- Tregs and total

IgE for predicting the incidence of RRTIs

was 0.852, which was larger than that of

any of the three indicators alone, with sig-

nificant differences. Collectively, the com-

bined detection of the three indicators is

beneficial to improving the detection rate

of RRTIs.

Nevertheless, this study is limited. The

obtained predictive values are focused on

the analysis of global RRTIs (upper and lower

respiratory tract) compared to non-RRTIs.

Further studies are ongoing in our group.

In summary, serum 25-OH-D,

CD4+CD25+CD127- Tregs and total IgE

are abnormally expressed in children with

RRTIs, and their expressions are of great

differences among children at different

stages, sites of lesions and severities of ill-

ness. The expression of 25-OH-D has nega-

tive correlations with the expressions of

CD4+CD25+CD127- Tregs and total IgE, and

a positive correlation is observed between

434 Yang et al.

Investigación Clínica 65(4): 2024

the expressions of CD4+CD25+CD127- Tregs

and total IgE. The combined detection of

serum 25-OH-D, CD4+CD25+CD127- Tregs

and total IgE is conducive to enhancing the

detection rate of RRTIs.

ACKNOWLEDGMENTS

None.

Funding

This study was financially supported

by the Health Science and Research Project

of Kunming Municipal Health Commission

(No. 2022-06-01-005).

Conflict of interest

The authors declare no conflict of interest.

ORCID’s number authors

• Yanfei Yang (YY):

0009-0006-6324-5357

• Na Fan (NF):

0009-0000-9635-0360

• Xingzhu Liu (XL):

0009-0001-6107-5677

• Lin Wang (LW):

0009-0004-4028-0577

• Zhihai Wang (ZW):

0009-0007-0753-7782

• Yao Hou (YH):

0009-0003-6697-7391

• Ting Wang (TW):

0009-0007-9197-7499

• Yuqin Wu (YW):

0009-0008-1137-5250

Contribution of the authors

YY, TW and YW designed this study and

significantly revised this paper; NF, XL, LW,

ZW and YH performed this study and draft-

ed this paper. All authors have approved the

submission and publication of this paper.

REFERENCES

1. Paśnik J. Vaccines nonspecific - immu-

nostimulation in patients with recu-

rrent respiratory infections. Otolaryn-

gol Pol 2016; 70(6): 31-39. https://doi.

org/10.5604/01.3001.0009.4819

2. Dong F, Yu H, Ma J, Wu L, Liu T, Lv G,

Zhen J, Li X, Lewith G, Gu X. Exploring

association between gastrointestinal heat

retention syndrome and recurrent respi-

ratory tract infections in children: a pros-

pective cohort study. BMC Complement

Altern Med 2016; 16: 82. https://doi.

org/10.1186/s12906-016-1062-8

3. Wang X, Li X, Jin C, Bai X, Qi X, Wang

J, Zhang L, Li N, Jin N, Song W, Gao H,

Gao B, Zhang Y, Wang L. Association bet-

ween serum Vitamin A levels and recurrent

respiratory tract infections in children.

Front Pediatr 2021; 9: 756217. https://doi.

org/10.3389/fped.2021.756217

4. Zhang X, Ding F, Li H, Zhao W, Jing H,

Yan Y, Chen Y. Low serum levels of vita-

mins A, D, and E are associated with re-

current respiratory tract infections in

children living in Northern China: A case

control study. PLoS One 2016; 11(12):

e0167689. https://doi.org/10.1371/jour-

nal.pone.0167689

5. Magnus MC, Stene LC, Håberg SE, Nafs-

tad P, Stigum H, London SJ, Nystad W.

Prospective study of maternal mid-preg-

nancy 25-hydroxyvitamin D level and early

childhood respiratory disorders. Paediatr

Perinat Epidemiol 2013; 27(6): 532-541.

https://doi.org/10.1111/ppe.12080

6. Chen X, Murakami T, Oppenheim JJ,

Howard OMZ. Differential response of mu-

rine CD4+CD25+ and CD4+CD25- T cells

to dexamethasone-induced cell death. Eur

J Immunol 2004; 34(3): 859-869. https://

doi.org/10.1002/eji.200324506

7. Chen M, Deng H, Zhao Y, Miao X, Gu H, Bi

Y, Zhu Y, Guo Y, Shi S, Xu J, Zhao D, Liu F.

Toll-Like Receptor 2 modulates pulmonary

inflammation and TNF-α release mediated

by Mycoplasma pneumoniae. Front Cell In-

fect Microbiol 2022; 12: 824027. https://

doi.org/10.3389/fcimb.2022.824027

Detection of recurrent respiratory tract infections 435

Vol. 65(4): 426 - 435, 2024

8. Ruskamp J, Smit H, Rovers M, Hoek-

stra M, Schilder A, Brunekreef B, Wijga

A, Kerkhof M, de Jongste J, Sanders E.

Neonatal total IgE and respiratory tract

infections in children with intrauterine

smoke exposure. Arch Dis Child 2010;

95(6): 427-431. https://doi.org/10.1136/

adc.2009.162685

9. Fu Y, Lou H, Wang C, Lou W, Wang Y,

Zheng T, Zhang L. T cell subsets in cord

blood are influenced by maternal allergy

and associated with atopic dermatitis. Pe-

diatr Allergy Immunol 2013; 24(2): 178-

186. https://doi.org/10.1111/pai.12050

10. Eroglu C, Demir F, Erge D, Uysal P, Kirdar

S, Yilmaz M, Kurt Omurlu I. The relation

between serum vitamin D levels, viral in-

fections and severity of attacks in children

with recurrent wheezing. Allergol Immu-

nopathol 2019; 47(6): 591-597. https://

doi.org/10.1016/j.aller.2019.05.002

11. Ginde AA, Mansbach JM, Camargo CA Jr.

Association between serum 25-hydroxyvi-

tamin D level and upper respiratory tract

infection in the Third National Health and

Nutrition Examination Survey. Arch Intern

Med 2009; 169(4): 384-390. https://doi.

org/10.1001/archinternmed.2008.560

12. Korf H, Decallonne B, Mathieu C. Vita-

min D for infections. Curr Opin Endocri-

nol Diabetes Obes 2014; 21(6): 431-436.

https://doi.org/10.1097/MED.00000

00000000108

13. Watkins RR, Lemonovich TL, Salata RA.

An update on the association of vitamin D

deficiency with common infectious disea-

ses. Can J Physiol Pharmacol 2015; 93(5):

363-368. https://doi.org/10.1139/cjpp-

2014-0352

14. Qin S, Li L, Liu J, Zhang J, Xiao Q, Fan

Y, Wei X. CD4+CD25+Foxp3+ regula-

tory T cells regulate immune balance in

unexplained recurrent spontaneous abor-

tion via the Toll-like receptor 4/nuclear

factor-κB pathway. J Int Med Res 2020;

48(12): 300060520980940. https://doi.

org/10.1177/0300060520980940

15. Schenck LP, Surette MG, Bowdish

DM. Composition and immunologi-

cal significance of the upper respira-

tory tract microbiota. FEBS Lett 2016;

590(21): 3705-3720. https://doi.org/10.

1002/1873-3468.12455

16. Brusko TM, Hulme MA, Myhr CB, Ha-

ller MJ, Atkinson MA. Assessing the

in vitro suppressive capacity of regu-

latory T cells. Immunol Invest 2007;

36(5-6): 607-628. https://doi.org/10.

1080/08820130701790368

17. Tang Q, Bluestone JA. The Foxp3+ regu-

latory T cell: a jack of all trades, master of

regulation. Nat Immunol 2008; 9(3): 239-

244. https://doi.org/10.1038/ni1572

18. Ramasamy I. Vitamin D metabolism and

guidelines for Vitamin D supplementation.

Clin Biochem Rev 2020;41(3):103-126.

https://doi.org/10.33176/AACB-20-00006

19. Dąbrowska-Leonik N, Bernatowska E,

Pac M, Filipiuk W, Mulawka J, Pietrucha

B, Heropolitańska-Pliszka E, Bernat-

Sitarz K, Wolska-Kuśnierz B, Mikołuć

B. Vitamin D deficiency in children with

recurrent respiratory infections, with or

without immunoglobulin deficiency. Adv

Med Sci 2018; 63(1): 173-178. https://doi.

org/10.1016/j.advms.2017.08.001

20. Beale DJ. Analysis leads to unreliable re-

sults in study of Vitamin D and acute res-

piratory infection. J Am Geriatr Soc 2017;

65(5): 1103. https://doi.org/10.1111/jgs.

14797

21. Hatam LJ, Devoti JA, Rosenthal DW, Lam

F, Abramson AL, Steinberg BM, Bonagura

VR. Immune suppression in premalignant

respiratory papillomas: enriched functio-

nal CD4+Foxp3+ regulatory T cells and

PD-1/PD-L1/L2 expression. Clin Cancer

Res 2012; 18(7): 1925-1935. https://doi.

org/10.1158/1078-0432.CCR-11-2941.