Mechanism of augmentation of the antibody response in vitro by 2-mercaptoethanol in murine lymphocytes. II. A major role of the mixed disulfide between 2-mercaptoethanol and cysteine.
Five thiol compounds including 2-mercaptoethanol (2-ME) were examined for their augmenting effects on in vitro antibody response to sheep erythrocytes. Three compounds were effective with the following order of activity; 2-ME greater than dithiothreitol greater than cysteamine. Glutathione and thioglycollate failed to enhance the response. The same order or effectiveness was seen in the stimulation of [35S]cystine uptake by murine lymphocytes by these thiols. Murine lymphocytes took up cysteine five to six times more rapidly than cystine. It is, however, unlikely that 2-ME stimulation of cystine uptake is solely due to the reduction of cystine into cysteine, because 2-ME was still stimulatory after free thiol groups had disappeared in the medium containing 2-ME and [35S]cystine. The mixed disulfide of cysteine with 2-ME (Cys-2-ME) was found to be an only product after free thiols had been oxidized. [35S]Cys-2-ME was taken up by the lymphocytes with a comparable rate to cysteine via a transport system common to that of leucine and phenylalanine. Cysteine was, however, transported via a different route. It was observed that Cys-2-ME was readily metabolized to cysteine and glutathione after the uptake. Cys-2-ME added to cystine-free RPMI 1640 medium could support the antibody response as efficiently as cystine plus 2-ME. These observations strongly suggest that 2-Me stimulates cystine uptake and, therefore, enhances the antibody response through the formation of the mixed disulfide with cysteine.
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D003543:Cysteamine / Q000494:pharmacology; D003553:Cystine / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D005260:Female; D007518:Isoantibodies / Q000096:biosynthesis*; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D008623:Mercaptoethanol / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C
D000276:Adjuvants, Immunologic; D000596:Amino Acids; D007518:Isoantibodies; D003553:Cystine; D003543:Cysteamine; D008623:Mercaptoethanol; D004229:Dithiothreitol