Relationship between Lymphocyte Subpopulations and Vitamin D Levels in COVID-19 Pneumonia Patients

BACKGROUND: Some studies have shown that patients who are hospitalized with severe COVID-19 also have low levels of vitamin D. It is known that vitamin D can reduce the risk of infections and down regulate the immune/inflammatory reaction. OBJECTIVES: To investigate the association between vitamin D status and lymphocyte subpopulations in hospitalized pneumonia COVID-19 patients. METHODS: In 33 positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients with radiologic evidence of interstitial pneumonia and in 16 healthy control subjects matched for age, sex, and seasonality lymphocyte subpopulations and vitamin D levels were evaluated. RESULTS: The majority of patients with COVID-19 pneumonia (70.8%) presented vitamin D deficiency. The percentages of neutrophils presented a negative correlation (r = -0.74; P < 0.001), whereas the percentages of lymphocytes presented a positive correlation (r = 0.43; P < 0.01) with 25(OH)D. Moreover, vitamin D levels were positively correlated with CD3+ (r = 0.37, P < 0.05), CD4+ (r = 0.41, P < 0.05), CD8+ (r = 0.32, P < 0.07), and CD19+ (r = 0.38, P < 0.05). CONCLUSIONS: This preliminary study confirms the high prevalence of vitamin D deficiency in patients with COVID-19 pneumonia and that vitamin D deficiency is associated with a reduction of lymphocyte subsets and altered T-lymphocyte activation. This finding may contribute to clarify the mechanisms by which vitamin D influences the course and outcome of COVID-19 pneumonia.