The properties of plaque-forming cells from autoimmune and normal strains of mice with specificity for autologous erythrocyte antigens.

Treatment of mouse erythrocytes with the proteolytic enzymes, bromelain, reveals antigenic determinants not normally exposed on the erythrocyte surface. It was found that not only NZB mice, a known autoimmune strain, but also several normal strains of mice contain cells in small numbers in their spleens and in larger numbers in their peritoneal cavities which will form plaques against bromelain-treated MRBC. During in vitro culture the number of anti-BR-MRBC PFC increases slightly in the spleen cell populations whereas the number of these PFC in peritoneal cells increases dramatically to as many as 100,000 PFC/10(6) cells. The plaques detected in this assay contain a central lymphoid cell and their development, which requires the presence of complement and protein synthesis, is inhibited by anti-mouse immunoglobulin.