Adaptive immune system in severe COVID-19 patients in the first week of illness: A pilot study

INTRODUCTION: The presentation of the course of COVID-19-related T-cell responses in the first week of the disease may be a more specific period for adaptive immune response assessment. This study aimed to clarify the relationship between changes in peripheral blood lymphocyte counts and death in patients with COVID-19 pneumonia. METHODS: Thirty-three patients (14 females and 19 males) admitted for severe and desaturated COVID-19 pneumonia confirmed by polymerase chain reaction were included. Lymphocyte subsets and CD4(+)/CD8(+) and CD16(+)/CD56(+) rates were measured using flow cytometry from peripheral blood at admission and on the day of death or hospital discharge. RESULTS: Twenty-eight patients survived and five died. On the day of admission, the CD4(+) cell count was significantly higher and the saturation of O(2) was significantly lower in the deceased patients compared to the survivors (P < 0.05). The CD16(+)/CD56(+) rate was significantly lower on the day of death in the deceased patients than in discharge day for the survivors (P = 0.013). CONCLUSION: CD4(+) lymphocyte percentages and O2 saturation in samples taken on the day of admission to the hospital and CD16+/CD56+ ratios taken at the time of discharge from the hospital were found to be associated with the mortality in patients with severe COVID-19.