SA96: an immunopharmacological profile in vitro.

We have screened from various thiol compounds SA96 (2-mercapto-2-methylpropanolyl-L-cysteine) as a stimulant of LPS-induced proliferative response of murine lymphocytes, and the immunopharmacological profile of this compound was studied in vitro. SA96, only at 10(-3) M concentration, caused 3H-thymidine (3H-TdR)uptake in the presence of foetal calf serum (FCS). The effects of SA96 on the proliferative response to mitogens were biphasic. The uptake 3H-TdR induced by Con A or LPS was suppressed in a dose-dependent manner below 10(-4) M, but was enhanced at 10(-3) M in the case of LPS. The response to Con A was recovered from the suppression at 10(-3) M, but did not exceed the control level. Some experiments suggested that cysteine moiety might importantly contribute to the proliferative response caused by SA96. SA96 enhanced the PFC response to SRBC in vitro at 10(-5) approximately 10(-4) M (nonmitogenic doses), but markedly inhibited the elevated response in the presence of 2-mercaptoethanol (2-ME). On the other hand, PFC response to DNP-Ficoll )a T-independent antigen) was augmented by SA96 irrespective of the presence of 2-ME. These findings suggest that SA96, a thiol compound, may be useful as an immunomodulator like levamisole.