Effect of lipopolysaccharide (LPS) on the thymocyte response to PHA: strain difference.

Thymocytes responded well to PHA in terms of [3H]-TdR incorporation if they were precultured in the presence of LPS, whereas fresh thymocytes or thymocytes pre-cultured in the absence of LPS responded poorly to PHA. The PHA response of thymocytes pre-cultured with LPS for several hours was similar to that of fresh spleen cells in the kinetics and dose-response profiles. The effect of LPS was found on thymocytes from BALB/c.Cr, AKR/Jms, and DDD/1 mice, but was not observed on those from C3H/HeJms and C57Bl/6J mice, indicating that there is a strain difference in the PHA responsiveness of LPS-pre-cultured thymocytes. In contrast to thymocytes, the response of spleen cells to PHA was enhanced in both C57Bl/6J and BALB/c.Cr mice by pre-culture with LPS.