•   Promotes B cell differentiation to plasma cells and augmenting Ig production     •   Has anti-cancer activity mediated in part via actions on CD8+ T cells and NK cells     •   Promotes Tfh differentiation and germinal center formation     •   Promotes Th17 differentiation     •   Inhibits Th9 differentiation     •   Promotes autoimmune disease (type I diabetes, SLE, EAE, and colitis). Here, CD8A is linked to systemic lupus erythematosus.