T-lymphocyte independence of the antibody response to another specific mycobacterial phenolic glycolipid antigen (the PGL-1 antigen being specific for M.leprae) has been shown in lepromatous leprosy patients, also when very high anti-PGL-1 antibody levels (both IgM and IgG) were found in the absence of a specific T-cell mediated immune response [80]. The gene discussed is SDHD; the disease is leprosy.