COVID-19 Infection in Patients with Comorbidities: Clinical and Immunological Insight

AIM: Our study's objectives were to study the clinical and laboratory characteristics that may serve as biomarkers for predicting disease severity, IL-10 levels, and frequencies of different T cell subsets in comorbid COVID-19 patients. METHODS: Sixty-two hospitalized COVID-19 patients with comorbidities were assessed clinically and radiologically. Blood samples were collected to assess the T lymphocyte subsets by flow cytometry and IL-10 levels by ELISA. RESULTS: The most common comorbidities observed in COVID-19 patients were diabetes mellitus (DM), hypertension, and malignancies. Common symptoms and signs included fever, cough, dyspnea, fatigue, myalgia, and sore throat. CRP, ferritin, D dimer, LDH, urea, creatinine, and direct bilirubin were significantly increased in patients than controls. Lymphocyte count and CD4(+) and CD8(+) T-cells were significantly decreased in comorbid COVID-19 patients, and CD25 and CD45RA expression were increased. CD4(+) and CD8(+) regulatory T cells (Tregs) and IL-10 levels were significantly decreased in patients. CONCLUSIONS: Many parameters were found to be predictive of severity in the comorbid patients in our study. Significant reductions in the levels and activation of CD4(+) and CD8(+) T-cells were found. In addition, CD4(+) and CD8(+) Tregs were significant decreased in patients, probably pointing to a prominent role of CD8(+) Tregs in dampening CD4(+) T-cell activation.