A mechanism of the augmentation of antibody response in vitro by 2-mercaptoethanol: Facilitation of cystine uptake in murine lymphocytes

Abstract

The mechanism of augmentation of antibody response in vitro by 2-mercaptoethanol (2-ME) was investagated. By employing cystine-free RPMI-1640 medium, it was demonstrated that cystine was absolutely required for eliciting the in vitro antibody response in murine lymphocytes. The augmentation by 2-ME was completely dependent on the presence of cystine. Maximal response was reached when cysteine or cystine (as half cystine) was added at 2.5 mM where 2-ME did not further enhanced the response. The serial feeding of cysteine, but not of cystine, amplified its potentiating activity at lower concentration (≦1 mM). The addition of 10 −5 M 2-ME to cystine shifted the dose-response curve to lower concentrations by about one order of magnitude. It was found that 35S-cystine was incorporated into lymphocytes one fifth more slowly than 35S-cysteine. Cystine uptake was accelerated by about 2.5-fold in the presence of 10 −5 M 2-ME. These data suggest that one of the roles of 2-ME in augmenting antibody response in vitro is to facilitate the uptake of cystine which is contained in RPMI-1640 medium and which is utilized less efficiently than cysteine.