Mouse peritoneal cells: their ability to elicit or produce antibody after exposure to antigen.

The functional activities of peritoneal cells in exudates of normal mice were studied. Antigen-containing peritoneal cells were tested for their ability to induce antibody by transfer into normal syngeneic recipients. Collection of peritoneal cells at varying time intervals following intraperitoneal injection of formalin-killed pneumococci or capsular polysaccharide, resulted in a decrease with time in the ability of these cells to induce antibody in the recipient mice. This finding could be ascribed to changes in the cell population in the peritoneum as a result of antigen administration rather than to loss of immunogenic material from these cells. Evidence for this comes from experiments in which peritoneal cells collected ½-hour after antigen administration were maintained for up to 24 hours. The immunogenicity of carbohydrate antigen in these cells persists for at least 24 hours. Furthermore our morphological observations showed a drop in macrophages following antigen administration. Our findings indicate that peritoneal exudates also contain immunocompetent cells. For this study we used recipient mice irradiated with 650–800 r, which completely suppressed their antibody response. Peritoneal cells collected 2 hours after injection of formalin-killed pneumococci led to serum antibody in the irradiated recipients 7 days later. By partially fractionating peritoneal cells on glass surfaces, it could be shown that the cells not adhering to glass (lymphocytes and medium sized cells) were mainly responsible for this antibody response. Cells adhering to glass which contained most of the antigen-containing large macrophages and also medium sized cells, were much less effective in inducing antibody. In addition, peritoneal cells induced with thioglycollate medium consisting mainly of large macrophages and very few lymphocytes, actively induced antibody in normal recipients but failed to restore antibody production in the highly irradiated mice. The transfer of antibody formation to irradiated mice thus is due to immunocompetent cells in normal peritoneal exudates.