Comparative studies of cellular resistance to Candida albicans infections in mice

The quantitative extent of resistance induced by specific and nonspecific immunization to systemically induced C. albicans infection was investigated in mice. Animals were specifically immunized by i.p. injections of formalinized suspension of C. albicans. Nonspecific resistance was induced by temporally spaced subcutaneous injections of endotoxin. The mice were hallenged by i.v. injections of known numbers of C. albicans. Animals were sacrificed at 24 hours intervals; cultures of spleen, liver, and kidney for viable C. albicans were done on antibiotic blood agar. In vitro studies were evaluated by comparing kinetic curves of inactinations of c. albicans by macrophages from various systems, that is, from animals that wer immunized, endotoxin treated or treated with saline. Lymphocytes plus macarophasges from the various systems were also challenged to determine if the lymphocyte was functionally involved with the destruction of C. albicans. The most significant in vivo result was that fewer yeast were found in the kidneys of immunized animals. The kidneys of the endotoxin treated animasl and the saline treated animals were heavily infected. No significant differences were observed in the livers and spleens of the different groups throughout the experiement. In vitro results indicate that macarophages from immunized animals have slightly but sutatistically significant enhance cytopeptic capacities when compared to macrophages from endotoxin treated and saline treated animals. Lylmphocytes appeard to enhace the cytopeptic response after a temporal delay which was not observed in cultures containin gonoy macrophages. The data suggest that macrophages from immunized animals, endotoxin treated animals or saline treated animals yieled a steeper inactivation curve. Reflecting death of the challenge organism, than the systems containing lymphocytes form the various systems acting in conjunction with macrophages from a homologous or heterologous system. Lylmphocytes from immunized animals and lymphocytes from endotoxin treated animals did enhance the cytopeptic capacities of macrophages from saline treated animals when comparisons to the lymphocyte-macrophage saline control system were made. This enhanced cytopepsis that occurred n the presence of the lymphocyte was not as pronounced n systems containing lymphocytes and macrophages form immunized animals and/or endotoxin treated animals. The fact that endotoxin treated lymphocytes stimulate the cytopeptic capacities of saline treated macrophages indicates a mechanism for the induction of nonspecific resistance. This implies that the mechanism of nonspecific resistance included cellular components and that both the lymphocyte and macrophage participate.