SERUM ANTIBODY-RESPONSE TO ACTIVE INFECTION CRYPTOCOCCUS-NEOFORMANS AND ITS VARIETIES IN IMMUNOCOMPETENT SUBJECTS

Using a class-specific enzyme immunoassay IgG and IgA anticryptococcal antibody was measured in 400 serum specimens at 1 week to 11.7 years after diagnosis from 43 immunocompetent subjects with confirmed active cryptococcosis. The prevalence of IgG was 86% at diagnosis, rose to 1 00% by 2 weeks and remained high thereafter. IgA prevalence was 71% at diagnosis, rose to 75% at 2 weeks and then fell over 2 years. IgG and IgA prevalence in paediatric controls was 5% and 0%, respectively. Me an antibody levels showed the same pattern and neither levels nor prev alence were influenced by age, sex or site of infection. Patients with the variety gattii infection had a greater antibody response than tho se with the variety neoformans which was significant for IgA. Specific anticryptococcal antibody was regularly present in conjunction with c ryptococcal antigen at diagnosis. IgG persists but IgA falls over 1-2 years. The assay described may be a useful tool to study the antibody response and seroepidemiology of infection with C. neoformans.