Analysis of differences in lymphocyte subsets and CD4+ T cells immune activation between re-detectable positive and non-re-detectable positive COVID-19 convalescent patients

Abstract

Abstract Background: Recently many literature were reported on the re-detectable positive phenomenon of COVID-19 patients during recovery, but there were few studies on the lymphocyte subsets and T-lymphocyte activation indicators between the RP (re-detectable positive) and NRP (non-re-detectable positive) patients. The aim of this study was to analyze immunological characteristics of RP and NRP patients among convalescent patients from post-discharge COVID-19 patients. Methods: Anticoagulated whole blood samples were collected from 11HCs (healthy controls) and 66 COVID-19 convalescent patients, then the percentage of lymphocyte subsets and CD4+CD38+/HLA-DR+ T cells were tested with flow cytometry, SARS-CoV-2 S RBD-IgG antibody ( anti-spike protein receptor-binding domain IgG antibody) was detected by chemiluminescence. Results: B cells (%) in RP group was significantly lower than that in HC group (P=0.005), and B cells (%) decreased successively in HC, NRP and RP group, with significant differences among the three groups (P=0.016). CD3+ and CD8+T cells (%) in RP group were noticeably higher than that in NRP group (P=0.004,0.019, respectively), but there was no difference in CD4+T cells (%) and NK cells (%) among the three groups. The CD4+CD38+ and CD4+HLA-DR+T cells (%) in RP group were noticeably higher than that in HC group (P=0.025,0.018). ANOVA (Analysis of variance) of the three groups showed that CD4+CD38+ and HLA-DR+T cells (%) were also significant difference (P=0.037, 0.029), and CD4+HLA-DR+T cells (%) in the three groups increased in turn. Meanwhile, there was a substantial positive correlation between RBD-IgG titer and CD4+HLA-DR+(%) (P=0.003, r=0.517), and the RBD-IgG titer of HLA-DR + high group was obviously higher than that of HLA-DR + Low group (P=0.005). Conclusions: In this work, we analyzed the immunological characteristics of re-detectable positive COVID-19 convalescent patients through lymphocyte subsets, suggesting that the low B cells (%) and the increased CD4+HLA-DR+T cells (%) in the convalescent patients of COVID-19 may be related to re-detectable positive phenomenon.