Recent observations include correlation of central memory immune responses with TB vaccine efficacy, association of SIRPα+ cells in ESAT-6:CFP10-elicited multinucleate giant cell formation, early γδ T cell responses to TB, antimycobacterial activity of memory CD4+ T cells via granulysin production, association of specific antibody with antigen burden, and suppression of innate immune gene expression in infected animals. The gene discussed is CD4; the disease is tuberculosis.