Immunoregulatory processes induced by carrageenan in BALB/C mice.

This paper describes the induction of immunosuppression by multiple injections of Carrageenan-lambda (cgn) in BALB/C mice. While cgn alone induced non-specific suppression that persisted up to 25 days, priming with sheep red blood cells (SRBC) of mice within 10 days after cgn treatment prolonged the suppressive state. When these mice were given a secondary challenge 45 days after priming antigen (SRBC) specific suppression was observed. Thus multiple cgn treatment and priming with SRBC generated non-specific and specific suppressive states which were transferable by Thy 1+ Lyt 2+ splenocytes. Further using Indomethacin (Indo), an inhibitor of prostaglandin E2 (PGE2) synthesis, a significant reduction in the duration of suppressive state was achieved. Besides PGE2 induction, cgn treatment also prevented the augmentation of Ia+ macrophages in peritoneal exudate cells upon priming and the synthesis of thymocyte co-stimulating factor. The possible "microenvironment" created by cgn-SRBC administration that may help the induction of transferable suppression is discussed.