Broad phenotypic alterations and potential dysfunctions of lymphocytes in COVID-19 recovered individuals

Abstract

SummaryBackgroundLymphopenia is a typical symptom in the COVID-19 patients. While millions of patients are clinical recovered, little is known about the immune status of lymphocytes in these individuals.MethodsA clinical recovered cohort (CR) of 55 COVID-19 individuals (discharged from hospital 4 to 11 weeks), and 55 age and sex matched healthy donors cohort (HD) were recruited. Detailed analysis on phenotype of the lymphocytes in peripheral blood mononuclear cells (PBMCs) was performed by flow cytometry.FindingsCompared with cohort HD, the CD8+ T cells in cohort CR had higher Teff and Tem, but lower Tc1 (IFN-γ+), Tc2 (IL-4+) and Tc17 (IL-17A+) frequencies. The CD4+ T cells of CR had decreased frequency, especially on the Tcm subset. Moreover, CD4+ T cells of CR expressed lower PD-1 and had lower frequencies of Th1 (IFN-γ+), Th2 (IL-4+), Th17 (IL-17A+) as well as circulating Tfh (CXCR5+PD-1+). Accordingly, isotype-switched memory B cell (IgM-CD20hi) in CR had significantly lower proportion in B cells, though level of activation marker CD71 elevated. For CD3-HLA-DRlo lymphocytes of CR, besides levels of IFN-γ, Granzyme B and T-bet were lower, the correlation between T-bet and IFN-γ became irrelevant. In addition, taken into account of discharged days, all the lowered function associated phenotypes showed no recovery tendency within whole observation period.InterpretationThe CR COVID-19 individuals still showed remarkable phenotypic alterations in lymphocytes after clinical recovery 4 to 11 weeks. This suggests SARS-CoV-2 infection imprints profoundly on lymphocytes and results in long-lasting potential dysfunctions.FundingKunming Science and Technology Department (2020-1-N-037)