Increased CD95 (Fas) and PD-1 expression in peripheral blood T lymphocytes in COVID-19 patients

A low count of CD4(+)and CD8(+)lymphocytes is a hallmark laboratory finding in the coronavirus disease 2019 (COVID-19). Using flow cytometry, we observed significantly higher CD95 (Fas) and PD-1 expression on both CD4(+)T and CD8(+)T cells in 42 COVID-19 patients when compared to controls. Higher CD95 expression in CD4(+)cells correlated with lower CD4(+)counts. A higher expression of CD95 in CD4(+)and CD8(+)lymphocytes correlated with a lower percentage of naive events. Our results might suggest a shift to antigen-activated T cells, expressing molecules increasing their propensity to apoptosis and exhaustion during COVID-19 infection.