Tolerance to cryptococcal polysaccharide in cured cryptococcosis patients: failure of antibody secretion in vitro

Ten patients cured of cryptococcosis and 14 normal volunteers were immunized with subcutaneous injections of cryptococcal polysaccharide (CPS). Peripheral mononuclear cells cultured from the volunteers 7 days post-immunization secreted significant amounts of IgM, IgA and IgG antibody to CPS in vitro. In cell cultures obtained 7 days after immunization of patients, nine of 10 had neither IgM nor IgG antibody response to CPS, and eight lacked anti-CPS IgA. Depletion of T lymphocytes from patients' cell cultures did not promote specific antibody secretion to CPS by B cells. The intense, prolonged antigenaemia with CPS that accompanies cryptococcosis may be responsible for the failure of cured patients to have circulating anti-CPS-secreting cells after immunization.