Heat-inducible ATP-binding proteins of Candida albicans are recognized by sera of infected patients.

Four proteins from Candida albicans extracts have been isolated by ATP affinity chromatography. These proteins were found to be at elevated levels in extracts of cells raised from 25 degrees C to 37 degrees C, but were present at low levels in cells grown at 25 degrees C. The molecular masses of the proteins (38-42 kDa, 66-68 kDa, 70-72 kDa and 74-76 kDa) correspond to the published sizes of C. albicans heat-shock proteins. Three of the four proteins were recognized by the sera of patients with oral and/or oesophageal C. albicans infections, with the 70-72 kDa protein reacting in all cases tested. Binding of antibodies to two of the other proteins (38-42 kDa and 74-76 kDa) differed from patient to patient. IgA antibodies were the dominant immunoglobulin class in these mucosal C. albicans infections. The IgA antibody titre may be of diagnostic value and seemed to be correlated to the severity of infections, with a higher level in oesophageal infections compared to oral infections. Antibody binding to these proteins was specific as the sera did not show the same enhanced recognition with bacterial or HeLa cell heat-shock proteins.