Thymoma and late onset mucocutaneous candidiasis associated with a plasma inhibitor of cell-mediated immune function.

A case is described of chronic mucocutaneous candidiasis in association with thymoma. A plasma inhibitor of certain in vitro tests of cell mediated immune function, both of autologous and of normal cells was isolated from the patient's blood and shown to be stable on heating to 56 degrees C for 1 hour and to freezing and thawing. Isolation of the active fraction of Sephadex G-200 suggested a m.w. of 50,000-65,000 daltons. Despite disappearance of the inhibitor after apparently curative radiotherapy, suggesting the tumour was the origin, the chronic mucocutaneous candidiasis persists. The association of plasma inhibitors of immune function, with and without thymoma and chronic mucocutaneous candidiasis is reviewed and the possible nature of the substance discussed.