2-Mercaptoethanol acts as a potentiating factor of interleukin-2-dependent lymphocyte proliferation.

An interleukin-2 (IL-2) dependent cell line which could be grown continuously with crude concanavalin A-stimulated rat or mouse spleen cell culture supernatant could not survive for over 48 hr in the culture medium supplemented with partially purified or recombinant IL-2. The cell growth was restored by adding another factor obtained from the same crude culture supernatant. This potentiating activity which was physicochemically inseparable from serum albumin was also obtained from the culture medium containing 2-mercaptoethanol (2-ME) and incubated at 37 C for 24 hr without the spleen cells. By further experiments, it was demonstrated that 2-ME itself had the potentiating activity on the IL-2-dependent proliferation of this cell line and cysteine mediated the activity of 2-ME. The cells could not enter S-phase in the absence of 2-ME even in the presence of IL-2.