Mannan-specific and mannan-induced T-cell suppressive activity in patients with chronic mucocutaneous candidiasis

We have studied T- and B-cell responses to antigens of Candida albicans in 18 patients suffering from chronic mucocutaneous candidiasis. We have shown that in vitro production of antibody to one of these antigens, mannan, was absent during the active phase of the disease and that this absence was consequent to the activation of specific CD8(+) and CD8(-) suppressor T lymphocytes. Such activation was also observed when control T lymphocytes were incubated in the presence of monocytes and a high concentration of mannan. This suppressive effect was specific to antigens of Candida albicans, was radiosensitive, and was not consequent to the secretion of prostaglandin E2. It appeared as well that the induction of these suppressor T cells was HLA-DQ restricted. The suppressor T-cell activity induced by antigens of Candida albicans in vitro is thus comparable to the suppressor T-cell activity observed in vivo in patients affected with chronic mucocutaneous candidiasis. Defective handling of mannan by monocytes could result in the accumulation of mannan, resulting in the activation of specific T suppressor cells and in the consequent cellular immunodeficiency specific to Candida albicans. Successful treatment of the candidiasis resulted in complete correction of the immune abnormalities.