EBV transformation induces overexpression of hMSH2/3/6 on B lymphocytes and enhances γδT-cell-mediated cytotoxicity via TCR and NKG2D

The function of γδ T cells in humoral immune responses

PURPOSE

The purpose of this review is to discuss the role of γδ T cells played in humoral immune responses.

BACKGROUND

The γδ T cell receptor (γδ TCR) recognizes antigens, including haptens and proteins, in an MHC-independent manner. The recognition of these antigens by γδ TCRs crosses antigen recognition by the B cell receptors (BCRs), suggesting that γδ T cells may be involved in the process of antigen recognition and activation of B cells. However, the role of γδ T cells in humoral immune responses is still less clear.

METHODS

The kinds of literature about the γδ T cell-B cell interaction were searched on PubMed with search terms, such as γδ T cells, antibody, B cell responses, antigen recognition, and infection.

RESULTS

Accumulating evidence indicates that γδ T cells, independent of αβ T cells, participate in multiple steps of humoral immunity, including B cell maturation, activation and differentiation, antibody production and class switching. Mechanically, γδ T cells affect B cell function by directly interacting with B cells, secreting cytokines, or modulating αβ T cells.

CONCLUSION

In this review, we summarize current knowledge on how γδ T cells take part in the humoral immune response, which may assist future vaccine design.

Resident human dermal γδT-cells operate as stress-sentinels: Lessons from the hair follicle

Murine γδT-cells have stress-surveillance functions and are implicated in autoimmunity. Yet, whether human γδT-cells are also stress sentinels and directly promote autoimmune responses in the skin is unknown. Using a novel (mini-)organ assay, we tested if human dermis resident γδT-cells can recognize stressed human scalp hair follicles (HFs) to promote an alopecia areata (AA)-like autoimmune response. Accordingly, we show that γδT-cells from healthy human scalp skin are activated (CD69⁺), up-regulate the expression of NKG2D and IFN-γ, and become cytotoxic when co-cultured with autologous stressed HFs ex vivo. These autologous γδT-cells induce HF immune privilege collapse, dystrophy, and premature catagen, i.e. three hallmarks of the human autoimmune HF disorder, AA. This is mediated by CXCL12, MICA, and in part by IFN-γ and CD1d. In conclusion, human dermal γδT-cells exert physiological stress-sentinel functions in human skin, where their excessive activity can promote autoimmunity towards stressed HFs that overexpress CD1d, CXCL12, and/or MICA.

Prognostic impact of EBV serostatus in patients with lymphomas or chronic malignancies undergoing allogeneic HCT

The influence of the donor (D) and recipient (R) pre-transplant Epstein-Barr Virus (EBV) serostatus on transplant outcomes (overall survival, relapse-free survival, relapse incidence, non-relapse mortality, acute and chronic GVHD) in 12,931 patients with lymphomas or chronic malignancies undergoing allogeneic hematopoietic cell transplant (allo-HCT) between 1997-2016 was analyzed. In multivariate analysis, the risk of development of chronic GVHD was increased for EBV R+/D+ (HR = 1.26; p = 0.003), R+/D- (HR = 1.21; p = 0.044), and R-/D + (HR = 1.21; p = 0.048) in comparison to R-/D- transplants. No significance was shown for other transplant outcomes; however, in univariate analysis, EBV-seropositive patients receiving grafts from EBV-seropositive donors (EBV R+/D+transplants) had inferior transplant outcomes in comparison to EBV-seronegative recipients of grafts from EBV-seronegative donors (EBV R-/D-): inferior overall survival (59.6% vs 65.9%), inferior relapse-free survival (51.1% vs 57.5%), increased incidence of chronic GVHD (49.5% vs 41.8%), and increased incidence of de novo chronic GVHD (30.5% vs 24.0%). In conclusion, an EBV-negative recipient with lymphoma or chronic malignancy can benefit from selection of an EBV-negative donor in context of chronic GVHD, while there are no preferences in donor EBV serostatus for EBV-seropositive recipient.

Protective Role of γδ T Cells in Different Pathogen Infections and Its Potential Clinical Application

γδ T cells, a subgroup of T cells based on the γδ TCR, when compared with conventional T cells (αβ T cells), make up a very small proportion of T cells. However, its various subgroups are widely distributed in different parts of the human body and are attractive effectors for infectious disease immunity. γδ T cells are activated and expanded by nonpeptidic antigens (P-Ags), major histocompatibility complex (MHC) molecules, and lipids which are associated with different kinds of pathogen infections. Activation and proliferation of γδ T cells play a significant role in diverse infectious diseases induced by viruses, bacteria, and parasites and exert their potential effector function to effectively eliminate infection. It is well known that many types of infectious diseases are detrimental to human life and health and give rise to high incidence of illnesses and death rate all over the world. To date, there is no comprehensive understanding of the correlation between γδ T cells and infectious diseases. In this review, we will focus on the various subgroups of γδ T cells (mainly Vδ1 T cells and Vδ2 T cells) which can induce multiple immune responses or effective functions to fight against common pathogen infections, such as Mycobacterium tuberculosis, Listeria monocytogenes, influenza viruses, HIV, EBV, and HBV. Hopefully, the gamma-delta T cell study will provide a novel effective way to treat infectious diseases.