The immunological response of Egyptians to coronavirus disease-19 infection: a cohort study of lymphocyte populations and peripheral blood counts

Abstract

Background The worldwide pandemic of COVID-19 infection that started in 2019 still lays its shadows over all populations of the world. COVID-19 infection presented with a spectrum of symptoms that varied from wave to wave, and also led to a wide number of long-term sequelae. Many immune system cells and cytokines were implicated in COVID-19 pathophysiology. Thus, many immuno-modulator and immuno-suppressive drugs were used in the management of severe cases. Lymphocytes are the key players of immune system, the change in their count and different subsets is expected to vary with COVID-19 infection. Objective The current study aimed to evaluate the role of peripheral blood lymphocyte subsets in predicting the outcome of COVID-19 patients and to investigate their correlation with different clinical and laboratory variables. Materials and methods The study included 64 patients hospitalized with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). They were stratified according to in-hospital mortality into survivors and nonsurvivors. Demographic, clinical and laboratory data were collected. Flowcytometric evaluation of lymphocyte subsets was done on admission. Results and conclusion Nonsurvivors showed lower relative lymphocyte count, higher absolute neutrophil count, and higher neutrophil to lymphocyte ratio (NLR) compared with survivors (P = 0.034, 0.006, 0.011; respectively). NLR at a cut off 15.3 had a sensitivity of 70.59% and specificity of 61.29% for predicting mortality in COVID-19 patients. The relative and absolute counts of lymphocyte subsets did not show a statistically significant difference between the two groups. Platelet count showed statistically significant positive correlation with absolute counts of total T lymphocytes, T helper, T cytotoxic, and B lymphocytes. The platelet to lymphocyte ratio (PLR), NLR and D-dimer results were negatively correlated with the total T lymphocytes, T helper, T cytotoxic, naïve T cytotoxic and B lymphocyte absolute counts. The NLR, absolute neutrophil count and platelet count may serve as adjuvant predictors of survival in COVID-19 disease. Although lymphocyte subsets did not differ statistically across survival groups, their correlation with other possible prognostic markers may justify further investigation on their role in COVID-19 pathophysiology.