Isolation of immunodominant antigens from sera of patients with systemic candidiasis and characterization of serological response to Candida albicans.

Candidal antigens were isolated by affinity chromatography from the sera of patients with disseminated Candida albicans infections. The immunodominant 47-kilodalton (kDa) antigen appeared to be a heat-stable breakdown product of several larger heat-labile components (84 to 92, 74 to 79, and 66 to 72 kDa). It was undetectable in normal sera and sera from four patients with systemic C. parapsilosis, C. tropicalis, and C. krusei infections. Serum samples from 92 patients with proven systemic C. albicans infections were examined by the immunoblot technique. Seventy-four patients had detectable antibody, and 92% of these produced antibody to the 47-kDa antigen. All survivors had major serological responses to this antigen, whereas patients who died had no, minor, or fading responses. Fifty-five of the patients were neutropenic following cytotoxic chemotherapy for malignancies, usually lymphoproliferative disorders (hematological patients). The remainder were surgical or medical patients (nonhematological). Hematological patients differed from nonhematological patients in the range of antigens that were commonly recognized by their immune systems, although antibodies to the 47- and 60-kDa antigens were frequently present in both groups. They also differed in that they produced mainly an immunoglobulin M (IgM) response, failing to seroconvent to IgG. This did not reduce survival rates, which were similar in both groups. It may be responsible, however, for the lower antigen titers that were observed in hematological patients when measured by reverse passive latex agglutination.