EFFECT OF AGING ON AUTOIMMUNE-RESPONSE TO RAT MALE ACCESSORY-GLANDS -YOUNG, BUT NOT AGED, ANTIGEN-PRESENTING CELLS EFFICIENTLY INDUCE SUPPRESSION IN AGED RATS

The present report analyzes the suppressor cell system of aged rats in an experimental model of autoimmunity to rat male accessory glands (R AG). A state of specific suppression to RAG was induced when young rat s are pretreated with peritoneal cells (PC) obtained from syngeneic yo ung rats i.p. injected 2 h previously with chromatographic fraction I (Sephadex G-100) (FI) of RAG (yFI-PC). Although the yFI-PC injection d iminished the DTH in aged rats the autoimmune response remained positi ve. Peritoneal cells obtained from aged rats injected with FI of RAG ( oFI-PC) did not suppress the DTH response in either aged or young rats . In both young and aged, pretreatment with yFI-PC stimulates spleen c ells capable of inducing suppression (inductor-phase suppressor cells) when they are transferred to young recipients. However, the spleen in ductor-phase suppressor cells of 12 month-old rats are unable to suppr ess the autoimmune response in their own aged environment. To obtain e ffective suppression in 12-month-old rats, the injection of yFI-PC was necessary prior to and subsequent to immunization. In this work we ob serve that 12-month-old rats could efficiently induce inducer phase an d effector-phase suppressor cells when the adequate young antigen-pres enting cells were present to stimulate them.