Abstract
The studies described were undertaken to determine the immunogenicity of single cell protein obtained from Candida lipolytica grown on n-alkanes (CLP) and to assess its ability to induce hypersensitivity tissue damage in the lung and gastrointestinal tract. Induction of humoral immunity was examined in the guinea pig, rabbit and mouse. Separated yeast components (whole cells, cell contents and cell walls) were used to identify the antigen concerned. Production of agglutinating and precipitating antibody was detected using prepared CLP antigens. The amount of antigen released during in vitro digestion was assessed. In addition, human sera were examined for antibody to CLP antigens. CLP induced a weak humoral response. The major antigenic material was found in the cell wall portion of the yeast, only small amounts of which were exposed during the in vitro digestion. Certain CLP antigens were recognised by agglutinating antibody in human serum. Induction of cell mediated immunity in guinea pigs was assessed by examining lymphocyte proliferation. Each of the yeast components was found to be capable of inducing lymphocyte proliferation. Ability of CLP to induce and elicit type I pulmonary hypersensitivity in guinea pig was compared with that of ovalbumin. Production of type III pulmonary hypersensitivity was examined in guinea pigs possessing agglutinating antibody to CLP antigen. CLP failed to produce either type I or type III hypersensitivity tissue damage, however, reaginic antibody was detected in guinea pigs treated to induce a type III hypersensitivity. Production of gastrointestinal hypersensitivity tissue damage was investigated in animals sensitized with CLP prior to oral exposure. Ingestion of high levels of CLP by parenterally sensitized guinea pigs enhanced the humoral response, which included production of reaginic antibody. No tissue damage was observed.