Immunophenotypic characterization of TCR æ T cells and MAIT cells in HIV-infected individuals developing Hodgkin's lymphoma

Background Despite successful combined antiretroviral therapy (cART), the risk of non-AIDS defining cancers (NADCs) remains higher for HIV-infected individuals than the general population. The reason for this increase is highly disputed. Here, we hypothesized that T-cell receptor (TCR) gamma delta cells and/or mucosal-associated invariant T (MAIT) cells might be associated with the increased risk of NADCs. gamma delta T cells and MAIT cells both serve as a link between the adaptive and the innate immune system, and also to exert direct anti-viral and anti-tumor activity. Methods We performed a longitudinal phenotypic characterization of TCR gamma delta cells and MAIT cells in HIV-infected individuals developing Hodgkin's lymphoma (HL), the most common type of NADCs. Cryopreserved PBMCs of HIV-infected individuals developing HL, matched HIV-infected controls without (w/o) HL and healthy controls were used for immunophenotyping by polychromatic flow cytometry, including markers for activation, exhaustion and chemokine receptors. Results We identified significant differences in the CD4(+) T cell count between HIV-infected individuals developing HL and HIV-infected matched controls within 1 year before cancer diagnosis. We observed substantial differences in the cellular phenotype mainly between healthy controls and HIV infection irrespective of HL. A number of markers tended to be different in V delta 1 and MAIT cells in HIV+HL+ patients vs. HIV+ w/o HL patients; notably, we observed significant differences for the expression of CCR5, CCR6 and CD16 between these two groups of HIV+ patients. Conclusion TCR V delta 1 and MAIT cells in HIV-infected individuals developing HL show subtle phenotypical differences as compared to the ones in HIV-infected controls, which may go along with functional impairment and thereby may be less efficient in detecting and eliminating malignant cells. Further, our results support the potential of longitudinal CD4(+) T cell count analysis for the identification of patients at higher risk to develop HL.