ANTIGEN DOSE-DEPENDENT DIFFERENCES IN IGE ANTIBODY-PRODUCTION ARE NOTDUE TO POLARIZATION TOWARDS TH1 AND TH2 CELL SUBSETS

The quality of the humoral immune response against protein antigens in CBA/J mice is dependent on the antigen dose used for immunization: lo w doses induce high titers of IgE antibodies, whereas high doses promo te the production of IgG2a antibodies but inhibit IgE formation. To in vestigate whether the reciprocal regulation of antibody production is possibly due to a differential activation of Th1 and Th2 cell populati ons in the two immunization groups, the cytokine pattern of spleen cel ls from both groups, cultured with antigen in vitro, was analyzed by m easurement of intracellular and secreted cytokine levels. The data pre sented show that in vitro restimulated spleen cells from mice primed w ith low as well as with high doses of antigen produce predominantly th e Th2 cytokines IL-4 and IL-10 but reduced levels of IL-12. The releas e of IFN-gamma is only slightly enhanced compared to unstimulated cont rol cultures. The results indicate that CD4(+) T cells in both groups belong mainly to the Th2 cell subset. This finding is contradictory to the general allegation that the antigen dose is decisive for the pola rization of Th1 versus Th2 immune responses and shows that the antigen dose-dependent regulation of IgE antibody production is not due to di fferential polarization towards Th1 and Th2 cells.