Epstein-Barr virus effect on frequency of functionally distinct T cell subsets in children with infectious mononucleosis

Comparison of immune responses in children with infectious mononucleosis caused by Epstein-Barr virus at different infection stages

INTRODUCTION

Infectious mononucleosis (IM) is a common infectious disease in children mainly caused by Epstein-Barr virus (EBV) infection, followed by abnormal immune response, and resulting in serious complications. However, there are few clinical analyses of immune responses in children with IM at different stages.

METHODS

This study combined EBV serological test and EBV DNA test to diagnose the infection status of children with IM, and the infection status was divided into primary acute IM infection (AIM), primary late IM infection (LIM) and reactivation IM infection (RIM).

RESULTS

The results revealed that the absolute numbers of leukocytes and CD8+ T lymphocytes in primary IM infection were significantly higher than those in reactivation infection, while the frequencies of CD4+ T lymphocytes and B cells were significantly lower than those in reactivation infection. In addition, the activities of ALT, AST, α-HBDH and LDH in liver function indicators in primary infection were significantly increased compared with reactivation infection. Similarly, the EBV DNA levels of the primary infection were significantly higher than that of the reactivation infection.

CONCLUSION

There are differences in immune response at different stages of infection, which can provide guidance for effective treatment in children with IM infection.

Interleukin-35 has a Protective Role in Infectious Mononucleosis-Induced Liver Inflammation Probably by Inhibiting CD8+ T Cell Function

Interleukin (IL)-35 plays an immunosuppressive role in infectious diseases, autoimmune disorders, and cancers. However, IL-35 expression and its regulation of CD8⁺ T cells in infectious mononucleosis (IM) are not fully understood. In this study, three groups of participants were compared, including twenty-three patients of IM without liver inflammation, twenty-eight patients of IM with liver inflammation, and twenty-one controls. Plasma and peripheral blood mononuclear cells (PBMCs) were isolated. CD8⁺ T cells were purified. Plasma IL-35 was measured by ELISA. PBMCs and CD8⁺ T cells were stimulated with recombinant human IL-35 in vitro. Perforin and granzyme B secretion was assessed by ELISPOT. Immune checkpoint molecule expression was investigated by flow cytometry. CD8⁺ T cells were co-cultured with HepG2 cells in direct contact and indirect contact manner. The cytotoxicity of CD8⁺ T cells was calculated by measuring lactate dehydrogenase release and proinflammatory cytokine expression. There was no significant difference in plasma IL-35 levels between patients with IM without liver inflammation and the controls, but the IL-35 level was notably increased in patients with IM who presented with liver inflammation and negatively correlated with aminotransferase. CD8⁺ T cells in patients with IM with liver inflammation showed stronger cytotoxicity. IL-35 stimulation inhibited CD8⁺ T cell-induced target cell death in patients with IM, mainly through suppression of IFN-γ/TNF-α secretion and elevation of immune checkpoint molecule expression, but did not affect perforin or granzyme B secretion. The current data indicated that IL-35 dampened the cytotoxicity of CD8⁺ T cells in patients with IM probably via repression of cytokine secretion. Elevated IL-35 may protect against CD8⁺ T cell-induced liver inflammation in patients with IM.

HLA-DR Expression Level in CD8+ T Cells Correlates With the Severity of Children With Acute Infectious Mononucleosis

Background

This study aimed to assess the host immune signatures associated with EBV infection and its clinical value in indicating the severity of children with acute infectious mononucleosis (IM).

Methods

Twenty-eight pediatric patients with IM aged 3–8 years were enrolled. The immune phenotypes and cytokine secretion capability of T cells were detected.

Results

The percentages and absolute numbers of CD3⁺ and CD8⁺ T cells were significantly increased in IM patients compared with HCs. The percentages of Naïve CD4⁺ and CD8⁺ T cells were decreased but with increased percentages of memory CD4⁺ and CD8⁺ T subsets. Our results showed the upregulation of active marker HLA-DR, TCR-αβ, and inhibitory receptors PD-1, TIGIT in CD8⁺ T cells from IM patients, which suggested that effective cytotoxic T cells were highly against EBV infection. However, EBV exposure impaired the cytokine (IFN-γ, IL-2, and TNF-α) secretion capability of CD4⁺ and CD8⁺ T cells after stimulation with PMA/ionomycin in vitro. Multivariate analysis revealed that the percentage of HLA-DR⁺ CD8⁺ T cells was an independent prognostic marker for IM. The percentage of HLA-DR⁺ CD8⁺ T cells was significantly correlated with high viral load and abnormal liver function results.

Conclusion

Robust expansion and upregulation of HLA-DR in CD8⁺ T cells, accompanied with impaired cytokine secretion, were typical characteristics of children with acute IM. The percentage of HLA-DR⁺ CD8⁺ T cells might be used as a prominent marker not only for the early diagnosis but also for indicating the severity of IM.

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.

Dynamic Distribution and Clinical Value of Peripheral Lymphocyte Subsets in Children with Infectious Mononucleosis

OBJECTIVE

To study the dynamic change of peripheral lymphocyte subsets and its clinical value in children with infectious mononucleosis (IM).

METHODS

Thirty-six pediatric patients with IM, 19 children with IM-like symptoms but lacking the serological pattern compatible with EB virus infection, and 33 healthy children were enrolled. The changes of peripheral lymphocyte subsets were detected by flow cytometry on admission and on the fifth day of antiviral treatment, respectively. Indicators of liver function and routine blood count were also detected. Besides, the receiver operating characteristic (ROC) curve and the correlation of related indicators was analyzed.

RESULTS

When IM patients were admitted, the frequency and absolute number of T, CD4^-CD8⁺T, and CD4⁺CD8⁺T (DPT) cells were significantly increased while B cells were decreased; the frequency of CD4⁺CD8^-T cells were decreased, but its absolute number did not change significantly; the frequency of NK cells decreased, but its absolute number increased. The absolute number of CD4^-CD8⁺T most significantly positively correlated with serum lactate dehydrogenase (LDH) concentration which could reflect the severity of IM patients. After short-term treatment with acyclovir, elevated lymphocytes decreased, but only DPT-cell frequency and NK-cell absolute number were recovering towards normal. The ROC curve suggested that the frequency of B cells has better diagnostic value for IM in pediatric patients compared to other lymphocyte subsets.

CONCLUSIONS

Peripheral lymphocyte subsets are closely related to the condition of children with IM, and each subset plays a relatively different role in the diagnosis and evaluation of IM.

Clinical characteristics of primary and reactivated Epstein-Barr virus infection in children

Epstein-Barr virus (EBV) infection occurs commonly in children and presents as a primary or reactivated infection, which are difficult for clinicians to distinguish. This study investigated the clinical characteristics of the two types of infections. Children with detectable plasma EBV-DNA were retrospectively enrolled and divided into primary and reactivated infection group by EBV-specific antibody. We analyzed the patients' characteristics, clinical manifestations, complications, inflammatory biomarkers, and viral load. A total of 9.3% of children with reactivation were immunocompromised over the long-term. The primary infection mostly appeared as infectious mononucleosis (99.8%), while reactivation occurred as an infectious mononucleosis-like disease (65.0%), hemophagocytic syndrome (22.6%), chronic active EBV infection (5.3%) and lymphoma (3.5%). The incidence of fevers, cervical lymphoditis, periorbital edema, pharyngotonsillitis, hepatomegaly and splenomegaly in primary infection were 93.3%, 93.0%, 51.5%, 66.0%, 76.2% and 63.9%, respectively; the incidence of those symptoms in reactivation was 84.0%, 46.9%, 15.4%, 18.5%, 18.5%, and 43.3%, respectively. The incidence of digestive, respiratory, cardiovascular, neurological, hematological, genitourinary complications and multiple serous effusion in primary infection was 68.8%, 18.1%, 8.0%, 0.8%, 2.9%, 0.0% and 2.3%; whereas the incidence of these complications in reactivation was 56.2%, 22.5%, 14.1%, 8.0%, 38.9%, 0.3% and 19.0%. Patients with reactivation were more prone to multi-systemic damage. B-cells were lower, and CD8+ T-cells were higher in primary infection. Viral load was correlated with the level of different cytokines in primary and reactivated infection. EBV primary infection often presents as infectious mononucleosis. The reactivated infection affects more immunocompromised subjects with diverse and complex manifestations. Various complications are more commonly associated with reactivation as a result of different inflammatory responses to different types of infection.

The immunology of Epstein-Barr virus-induced disease

Epstein-Barr virus (EBV) is usually acquired silently early in life and carried thereafter as an asymptomatic infection of the B lymphoid system. However, many circumstances disturb the delicate EBV-host balance and cause the virus to display its pathogenic potential. Thus, primary infection in adolescence can manifest as infectious mononucleosis (IM), as a fatal illness that magnifies the immunopathology of IM in boys with the X-linked lymphoproliferative disease trait, and as a chronic active disease leading to life-threatening hemophagocytosis in rare cases of T or natural killer (NK) cell infection. Patients with primary immunodeficiencies affecting the NK and/or T cell systems, as well as immunosuppressed transplant recipients, handle EBV infections poorly, and many are at increased risk of virus-driven B-lymphoproliferative disease. By contrast, a range of other EBV-positive malignancies of lymphoid or epithelial origin arise in individuals with seemingly intact immune systems through mechanisms that remain to be understood.