Flow Cytometric Analysis Revealed a Significant Accumulation of Terminally Differentiated T cell Subtypes in the Circulating Lymphocytes of Cytomegalovirus (CMV) Positive Follicular Lymphoma Patients

Abstract

Follicular lymphoma (FL), a non-Hodgkin lymphoma, is an indolent cancer of the B cell lineage that runs a chronic deterioration course that can result in multiple treatment episodes leading to resistance and possible transformation to diffuse large B cell lymphoma. Cytomegalovirus (CMV) reactivation during chemotherapy or after an organ or hematopoietic stem cell transplantation is a major cause of morbidity and mortality. This study tests the hypothesis that some of the heterogeneity of FL might result from chronic infection with Cytomegalovirus (CMV). This research was intended to appraise the impact of CMV infection on the subtypes of T cells in follicular lymphoma patients. We accessed stored peripheral blood mononuclear cells (PMBCs) from patients of known CMV serostatus recruited into an FL clinical trial. We undertook a multicolour flow cytometric analysis of the PBMCs and compared the number of lymphocyte subtypes of CMV-positive and CMV-negative FL patients. Data showed a significant increase in the quantity of terminally differentiated (TEMRA) T cell subsets, including EM3-CD8 (P=0.005), EM3-CD4 (P=0.018), E-CD4 (P=0.029), E-CD8 (P=0.033) and pE2-CD4 (P=0.046) phenotypes, as well as increased NKT cells (P=0.031) among CMV-positive patients compared to the negative group. Our findings support the hypothesis that recurrent infections characterise CMV infection in FL due to accelerated immune senescence and the accumulation of exhausted T cells. Based on the data, a case could be argued for the routine application of CMV screening in FL before treatment with chemo-immunotherapy to implement enhanced infection surveillance in CMV-positive patients. These discoveries can eventually help improve the treatment approaches in the management of FL toward a combinatorial viewpoint for direct cytotoxic and indirect immunomodulatory outlook