Spleen cells from CBA or congenitally athymic ("nude") mice were pretreated with various concentrations of DNP coupled to a copolymer of D-glutamic acid and D-lysine (DNP37-D-GL), under various conditions of time and temperature. After washing, they were then cultured for 3 days with the direct B cell immunogen, DNP coupled to Salmonella adelaide flagella (DNP-FLA). Under all circumstances tried, exposure of cells to 1 µg/ml DNP-D-GL caused a 70–100% depression in the subsequent DNP-specific PFC response, and 100 ng/ml caused a lesser but still substantial effect. At the concentrations used, DNP-D-GL did not affect irrelevant antibody responses. Though cells from nude mice responded somewhat less well to DNP-FLA than those from CBA mice, no significant difference in the reaction of the two populations to the tolerogen was noted. This demonstrates that DNP-D-GL can, as previously suspected, directly cause unresponsiveness in B lymphocytes
