Nonspecific and Candida ‐Specific Immune Responses in Mice Suppressed by Chronic Administration of Anti‐μ

CBA/J mice were immunosuppressed by repeated administration of goat antibody specific for μ chain of immunoglobulin M (IgM) and tested for nonspecific and Candida albicans ‐specific immune responses. Immunosuppression was demonstrated by a dramatic reduction in the number of antibody‐forming cells in the spleens of anti‐μ‐treated mice when immunized with sheep erythrocytes, by greatly reduced in vitro responsiveness of both spleen and lymph node lymphocytes from anti‐μ‐treated mice to lipopolysaccharide, and by a large reduction in the number of splenic IgM‐posttive cells. T cell function, on the other hand, appeared to be relatively unaltered in anti‐μ‐treated animals, in the cytotoxic T lymphocyte activity against an allogeneic target was similar in splenocyte cultures from anti‐μ‐ and mock‐treated animals, and splenic and lymph node lymphocytes proliferated in response to concanavalin A in a lymphocyte stimulation assay. Moreover, Candida ‐specific delayed hypersensitivity to two different Candida antigens, one cell wall‐derived (GP) and the other cell membrane‐derived (BEX), was of comparable intensity in immunosuppressed and normal animals. When anti‐μ‐ and mock‐treated mice were immunized by the cutaneous inoculation of viable C. albicans blastospores and then challenged intravenously to assess the development of protective immunity, only mock‐treated animals, male and female, had significant (p ≤ 0.05) protective responses demonstrable by reduction in the number of colony‐forming units cultured from their kidneys 28 days after intravenous challenge. If consideration was given to the number of animals which had cleared Candida completely from the kidney, however, there appeared to be protective responses operative in the female anti‐μ‐treated animals as well. Neither anti‐μ‐treated males nor females, when immunized and challenged with C. albicans , produced Candida ‐specific antibody detectable by counte‐rimmunoelectrophoresis, whereas all immunized and challenged mock‐treated animals produced antibody. The data are consistent with the hypothesis that anti‐μ treatment has little effect on multiple cellular immune functions, including those specific for C. albicans , and the combination of antibody, cell‐mediated immunity and innate defenses are responsible for solid systemic defense against the fungus.