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

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.

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.

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.

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.