Abstract
Coronavirus infectious disease 2019 (COVID-19) confirmed cases are characterized by T lymphopenia. Total apoptotic and cytotoxic T-lymphocyte antigen-4 (CTLA-4) expressing cells among CD4
+
/CD8
+
cells were analyzed in 24 COVID-19 patients (16 out-patients and 8 in-patients) and 18 healthy volunteers using flow cytometry to detect their possible role in T lymphopenia. Hospitalized patients did not show significant difference compared to non-hospitalized patients. While the percentage and absolute count of CD4
+
/CD8
+
cells were significantly reduced in COVID-19 cases compared to healthy control (
P
< .05), the proportion of apoptotic and CTLA-4 expressing CD4
+
/CD8
+
cells were significantly up-regulated in COVID-19 patients (
P
< .05). In addition, apoptotic and CTLA-4
+
/CD4
+
cells were directly related to dyspnea duration, chest CT score, ferritin, and C-reactive protein and inversely correlated with platelet count in COVID-19 patients. While apoptotic and CTLA-4
+
/CD8
+
cells were directly related to lymphocyte count in COVID-19 patients. The apoptotic and CTLA-4
+
cells were directly related to each other in CD4
+
/CD8
+
cells (
P
< .05). White blood cells (WBCs) (×10
3
/L), eosinophils (ratio and count), lymphocyte ratio, neutrophil ratio, neutrophil/lymphocyte ratio, neutrophil/CD4 ratio, neutrophil/CD8 ratio, CD4
+
cells ratio, and CTLA-4
+
cells percentage), and CD8
+
cells (ratio, count, total apoptotic cell, and CD152
+
cells) were all found to be significantly altered in association with COVID-19. Total lymphopenia and depletion of CD4
+
/CD8
+
cells are characterizing COVID-19 patients. Increased apoptosis and CTLA-4 expression in CD4
+
/CD8
+
cells in COVID-19 and their correlations with reduced cell count and severity indicators as CRP and ferritin can be used for diagnosis and follow up of the clinical severity. Our current study proposes promising future diagnostic and therapeutic targets.