Clinical and morphological manifestations of immune system dysfunction in new coronavirus infection (COVID-19)

Abstract

Rapid development in 2020 of the COVID-19 pandemic caused by SARS-CoV-2 initially indicated signifi-cant involvement of the immune system. However, information on specific changes in organs of the immune system is still limited. A wide range of alterations was revealed in our study: from pronounced devastation of B-dependent and T-dependent zones of lymphoid tissue, reminiscent of changes in HIV infection at the AIDS stage, to hyperplasia of the tissue of lymph nodes and spleen of varying degrees. Analyzing the literature data, we focused on the fact that pathomorphological changes revealed in the autopsy studies of patients with a severe COVID-19 were accompanied by premortal lymphopenia in most cases. However, the cause of lymphopenia in COVID-19 has not yet been disclosed, authors of the review hypothesized that unregulated apoptosis of circulating lymphocytes is one of the potential lymphopenia inductors. Cytokine activation (“cytokine storm”) may be associated with lymphoid organs’ atrophy, which also contributes to a decrease in the circulating lymphocyte count. There is no doubt about the relevance of further identification of the immune cell apoptosis as one of the causes of lymphopenia and immune dysfunction in COVID-19 patients, which has prospects for pharmacological developments to manage lymphocytic apoptosis. Keywords: coronavirus infection, COVID-19, pathomorphology, lymphopenia, lymph nodes, spleen, lym-phocytic apoptosis