Although pathways other than IgM ALAb might induce complement deposition on T cells (37), we show here that CDC activity found in COVID-19 plasma samples is immunoglobulin dependent and that patients with IgM ALAb have significantly increased CDC against lymphocytes, suggesting a potential in vivo link between IgM ALAb and complement activity in patients’ lymphocytes. This evidence concerns the gene CD40LG and COVID-19.