Anti-Rabbit IgG polyclonal antibody [Cy5]

This study aimed to analyze the dynamic changes of lymphocyte subsets and specific antibodies in coronavirus disease 2019 (COVID-19) patients with different illness severity. The amounts of lymphocyte subsets and the levels of immunoglobulin M (IgM) and IgG antibody were retrospectively analyzed in 707 COVID-19 cases. The amounts of lymphocyte subsets were significantly decreased with the increased severity of illness and the levels of IgM and IgG were lower in critical cases than severe and moderate cases. In deceased patients, the lymphocytes subsets were significantly lower than recovered patients. However, the relationship between the levels of IgM and IgG and the amounts of lymphocyte subsets were not significantly correlated. During different stages of COVID-19, the total T cell, CD4+ T cell, and CD8+ T cell counts were gradually recovered to the normal levels in severe and critical groups but the changing trend was relatively stable in the moderate group. The production of IgM and IgG antibodies were delayed in critical groups but also could reach the peak levels at one month after illness onset and decreased to background levels. To detect the kinetics of lymphocytes and antibodies has important clinical value in predicting the illness severity and understanding the pathogenesis of COVID-19.

Circulating T-FH(cT(FH)) cells express CXCR5, PD-1, and, when activated, ICOS, and release IL-21. According to the production of IFN-gamma, IL-4, and IL-17 and expression of FoxP3, these cells are also classified as cT(FH)1, cT(FH)2, cT(FH)17, and cT(FR)cells, respectively. This CD4(+)T-cell subset is pivotal to efficient humoral immunity, and pregnancy appears to favor IgG production. Here, not only pregnancy amplified the in vivo production of anti-HBsAg IgG in HBV immunized women, but the frequency of cT(FH)cells was directly correlated with estradiol levels. In vitro, pregnancy-related dose of 17-beta-estradiol (E2) directly increased the percentage of different cT(FH)subsets. While E2 and progesterone (P4) increased the proportion of differentiated T(FH)cells derived from naive CD4(+)T-cells, only E2 amplified the release of IL-21 in those cell cultures. In addition, E2 and P4 increased the proportion of memory B cells and plasma cells, respectively. In SEB-activated B/T(FH)cell co-cultures, E2, in the presence of P4, increased the production of total IgG. Finally, among the hormones, P4 was stronger in upregulating the percentage of IL-10(+)T(FR)cells. Collectively, our findings suggested that E2 and P4 cooperate in the humoral immune response by favoring the expansion of different cT(FH)and B cell subsets.