Antibodies to Candida albicans do not prevent the occurrence of candidal vulvovaginitis. To determine if antibodies may be involved in enhancing infectivity, the effects of purified rabbit anti-Candida immunoglobulin G (IgG) on the in vitro cellular immune response to this organism was examined. In four individuals, 50 micrograms/mL rabbit anti-Candida IgG, but not control rabbit IgG, inhibited the lymphocyte proliferative response to Candida antigens by a mean of 92.3%. The degree of inhibition was proportional to antibody concentration over a 5-25 micrograms/mL range. Addition of antibody at the initiation of Candida incubation with peripheral blood mononuclear cells or up to 48 hours later led to a 60-83% inhibition; antibody addition 24 hours before Candida caused only a 29% inhibition. Addition of antibody to purified macrophages concomitantly with Candida or after an overnight incubation of macrophages and Candida, both followed by the addition of lymphocytes, demonstrated that the uptake and/or processing of Candida antigens by macrophages and the recognition by lymphocytes of Candida antigen on the macrophage surface were both inhibited by antibody. Candida-specific antibody may enhance the ability of this organism to escape immune destruction.