BCL6 and COVID-19: The numbers of CD4+CXCR5+Tfh, ICOS+Tfh, Bcl-6+Tfh and Bcl-6+B cells are decreased in lymph nodes and spleens, which are possibly associated with exclusively abundantTh1 cells, increased Treg cells (but not Tfr cells) and aberrant TNF-α production in COVID-19 lymph nodes in COVID-19 patients, as well as loss of GCs in lymph nodes and spleens from acute and dead COVID-19 patients (26, 152, 153).