DIETARY-PROTEIN INFLUENCES THE RESPONSIVENESS OF SPLENOCYTES TO CON-AIN GROWING MICE

The effects of dietary proteins containing different Levels of sulfur amino acid on the responsiveness of splenocytes to concanavalin A(Con A) were examined. The Con A-induced DNA synthesis of splenocytes in mi ce fed a purified egg protein(PEP) diet was significantly higher than those in mice fed a soy protein isolate(SPI) or casein diet. Reduced g lutathione(GSH) and 2-mercaptoethanol(2ME) markedly stimulated Con A-i nduced DNA synthesis in vitro, and the stimulatory effects of 2-ME wer e more marked in SPI and casein diet groups compared to the PEP diet g roup. In contrast, L-buthionine-(S, R)-sulfoximine(BSO) markedly inhib ited Con A-induced DNA synthesis in splenocytes. The degree of inhibit ion was greater in the order SPT, casein and PEP diet groups. The Con A-induced IL-2 secretion from splenocytes in the SPI diet group was si gnificantly lower than those in casein and PEP diet groups when BSO wa s added to the medium. IL-2 secretion from splenocytes in the SPI diet group was significantly increased by L-methionine supplementation in the diet. These results suggest that the sulfur amino acids content in the dietary protein may. play a key role in the regulation of lymphoc yte responsiveness to Con A in growing mice. (C) 1998 Elsevier Science Inc.