Studies of CD45+ and CD46+ expression on the peripheral blood lymphocyte subsets of the post-COVID patients

The SARS-CoV-2 virus can enter the cells using S1 viral spike (S) protein, not only by binding to ACE2, but also through other cellular receptors. These candidate receptors include CD46, which, like CD45, belongs to pan-leukocyte receptors and is expressed on all types of lymphocytes. In turn, SARS-CoV-2 infection is accompanied by damage to almost all compartments of the immune system, mainly T lymphocytes. The purpose of the study was to evaluate the expression levels of CD45⁺ and CD46⁺ in various subpopulations of lymphocytes in patients who had undergone SARS-CoV-2 infection.

72 patients who had undergone SARS-CoV-2 infection were examined. Using flow cytometry technique, we determined CD45⁺ and CD46⁺ (panleukocyte marker for lymphocyte gating), CD45⁺ and CD46⁺, CD3⁺ (T lymphocytes), CD45⁺ and CD46⁺, CD3⁺, CD4⁺ (helper inducers), CD45⁺ and CD46⁺, CD3⁺, CD8⁺ (cytotoxic T-lymphocytes), CD45⁺ and CD46⁺, CD3⁺, CD56⁺ (TNK cells) CD45⁺ and CD46⁺, CD3^-, CD56⁺ (natural killers), CD45⁺ and CD46⁺, CD3^-, CD19⁺ (B lymphocytes), CD45⁺ and CD46⁺, CD3⁺, CD4⁺, CD25⁺ (activated helpers, early activation of lymphocytes), CD45⁺ and CD46⁺, CD3⁺, HLA-DR (activated T lymphocytes – late activation of lymphocytes). Our studies have shown that a decrease in CD46⁺ expression in T lymphocytes (CD3⁺) is accompanied by similar decrease of its expression in cytotoxic T lymphocytes (CD3⁺, CD8⁺), TNK (CD3⁺, CD56⁺), as well as in helpers T carrying markers of early activation (CD3⁺, CD4⁺, CD25⁺). At the same time, the most pronounced decrease was observed both among total T lymphocytes and cytotoxic T cells. In these patients, the expression level of CD46⁺ in B lymphocytes was slightly increased. Recent data suggest that there is no involvement of CD46 receptor on B lymphocytes. Our data suggest that the SARS-CoV-2 virus may affect the CD46 receptor. Such exposure may lead to promotion of the long-COVID (post-COVID) symptoms in such patients, thus requiring new approaches to correction of these disorders.