Precommitment of normal mouse peritoneal cells by erythrocyte antigens in relation to auto-antibody production

Abstract

WE have reported that peritoneal cells (PCs) from unstimulated mice can, after 2 h of incubation in the appropriate medium, start to secrete anti-sheep erythrocyte (SRBC) antibodies^1,2. We extended this observation by showing that PCs cultured in standard conditions for 4–6 d in the absence of SRBC, can form numerous haemolytic plaques, demonstrable by the ordinary techniques of local haemolysis (in Agarose, in liquid layer or in cellulose gum³). The immunological nature of this plaque-forming activity was established by the following criteria: complement dependency, inhibition by anti-mouse IgM serum and immunological specificity. Thus, we concluded^3,4 that PCs of normal adult mice had been stimulated previously by an unknown immunogen sharing common or cross-reacting determinants with SRBC, and that tissue culture conditions would derepress the built-in capacity of these cells to produce antibodies. Treatment of autologous erythrocytes by the proteolytic enzyme bromelain revealed that normal mouse spleen cells regularly produce antibodies against their own erythrocytes^5,6. This led us to investigate the behaviour of normal PCs towards SRBC or mouse red blood cells (MRBCs) treated by bromelain (BrMRBCs). We report here that mouse PCs in culture develop a plaque-forming activity against isologous BrMRBC as well as against SRBC, and we show that these two types of erythrocytes share some common antigen.