CD4+ T-Cell Depression is Linked to the Severity of COVID-19 and Predicts Mortality

Objective: Most patients with coronavirus disease (COVID-19) have abnormalities of lymphocyte subsets. This study aimed to determine the distribution of lymphocytes in patients with various severity levels of COVID-19 and to describe the relationship between the CD4(+) T helper and prognosis.Materials and Methods: Adult (>18 years old) patients with COVID-19 who followed up in a tertiary hospital were included in the study prospectively. Demographic and clinical characteristics of the patients were obtained from the hospital records. Peripheral flow cytometry was studied in patients with different severity of COVID-19 and different prognoses. Next, we analyzed the characteristics and predictive values of lymphocyte subsets in COVID-19 patients.Results: Totally 86 patients were included in the study, of which 21 (24.4%) had asymptomatic, 23 (26.7%) had mild/moderate, and 42 (48.8%) had severe/critical COVID-19. Severe/critical patients had lower lymphocyte levels and older age than asymptomatic patients (p<0.001 and p<0.001, respectively). We determined that decreased CD4(+) T cell ratio (p<0.001) and CD4(+)/CD8+ ratio (p<0.001) were indicative of the severity of the disease. CD4(+) T cell ratio on admission (odds ratio [OR]=0.858; p=0.033), day seven CD4(+) T cell ratio (OR=0.840; p=0.029), and C-reactive protein (CRP) levels (OR=1.014; p=0.043) were prognostic factors for mortality. According to receiver operating characteristics (ROC) curve analysis, the area under the curve was greater than 0.9 for decreased CD4(+) T cell ratio on admission and the seventh day. Conclusion: A low CD4+ T helper ratio predicts a poor prognosis. In combination with CRP, it can be used in clinical follow-up.