The differential effect of cholera toxin on the lymphocyte stimulation induced by various mitogens.
BALB/c spleen cells (5 x 10(6)) were cultured in 1 ml of serum-free RPMI 1640 medium for 3 days in order to examine the effect of cholera enterotoxin (CN) and its spontaneously formed toxoid (CD) on lymphocyte stimulation. Stimulation was assessed after addition of [3H] thymidine for the last 16 hours of culture. One microgram of CN per culture markedly reduced the baseline of [3H] thymidine incorporation and the stimulation due to phytohaemagglutinin (PHA), concanavalin A (con A) and bacterial lipopolysaccharide (LPS). One microgram of CD diminished the base-line to half, abolished the response to PHA, reduced the response to con A and had very little effect on the LPS-induced stimulation. One-tenth the amount (0-1 mug) of both CN and CD affected only the PHA reaction. A secondary response to haemocyanin in vitro was not decreased by this lower dose. The effect of 1 mug on CN on the LPS response could be reduced by pretreatment of the cells with CD, whereas the PHA reaction remained markedly diminished. Dibutyryl-cAMP added to culture tubes had a similar effect ot 1 mug of CN, affecting the PHA response much more than the response to LPS. Spleen cells of mice immunized with CD gave a significant proliferative response to both 1 mug of CD and CN. The results are interpreted as indicating a strong inhibitory effect of CN mediated by accumulation of intracellular cAMP. CD-immunized cells contain specific receptors for both CD and CN which probably compete with the sites responsible for adenylate cyclase stimulation by CN.
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D004768:Enterotoxins / Q000494:pharmacology*; D006433:Hemocyanins / Q000276:immunology; D037102:Lectins / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008934:Mitogens / Q000494:pharmacology*; D013154:Spleen / Q000276:immunology; D014121:Toxoids / Q000494:pharmacology; D014734:Vibrio cholerae / Q000276:immunology*
D004768:Enterotoxins; D037102:Lectins; D008070:Lipopolysaccharides; D008934:Mitogens; D014121:Toxoids; D003208:Concanavalin A; D003994:Bucladesine; D006433:Hemocyanins