Anti-FAS polyclonal antibody

In the immune system, T lymphocytes undergo rapid clonal expansion upon pathogen infection. Following pathogen clearance, most of proliferated T cells will be eliminated by the apoptosis pathway to keep the balance of immune cells. FASLG, by interacting with its cognate receptor FAS, plays a major role in controlling the T cell death. FASLG is a type II transmembrane protein, with its C-terminal extracellular domain responsible for interacting with FAS. The N-terminal cytosolic region, despite short and intrinsically disordered, plays critical roles on the protein stability and transportation. The correct localization, either on the plasma membrane or secreted with exosome, or shed into the extracellular region after protease cleavage, has a great impact on the proper function of FASLG. Following synthesis, FASLG is transported by intracellular vesicle transportation system to the final destination. In this report, ALG2, a molecule identified in the T cell apoptosis and shown to be involved in vesicle trafficking previously, was found to interact with FASLG and regulate FASLG transportation. Therefore, we identified a new regulating factor for FASLG function within T cells and also revealed a new pathway for ALG2 involvement in T cell apoptosis.

A low count of CD4(+)and CD8(+)lymphocytes is a hallmark laboratory finding in the coronavirus disease 2019 (COVID-19). Using flow cytometry, we observed significantly higher CD95 (Fas) and PD-1 expression on both CD4(+)T and CD8(+)T cells in 42 COVID-19 patients when compared to controls. Higher CD95 expression in CD4(+)cells correlated with lower CD4(+)counts. A higher expression of CD95 in CD4(+)and CD8(+)lymphocytes correlated with a lower percentage of naive events. Our results might suggest a shift to antigen-activated T cells, expressing molecules increasing their propensity to apoptosis and exhaustion during COVID-19 infection.