Anti-Cryptococcus neoformans antibodies during cryptococcosis in patients with the acquired immunodeficiency syndrome

We studied the anti-cryptococcal IgG antibody response in patients with the acquired immunodeficiency syndrome (AIDS) after Cryptococcus neoformans infection. The reactivity of 64 sera from 16 AIDS patients with cryptococcosis and 70 from noninfected HIV-negative individuals was measured against purified capsular polysaccharide by enzyme-linked immunosorbent assay (ELISA) or whole cryptococci by flux cytometry (FACS). AIDS patients had higher titres of antibodies by ELISA than controls. FACS analysis using the infecting isolate suggested antibody production was lower when the infecting isolate was serotype D. Lack of correlation between ELISA and FACS suggest antibodies produced during infection have a different specificity than that of normals. We did not find a correlation between antibody levels and clinical course. The lack of correlation between antibody and antigen titres even after pretreatment with pronase showed the proteinaceous substance unmasked by pronase is not composed only of specific antibodies.