Dose-dependent selective priming of Th1 and Th2 immune responses is achieved only by an antigen with an affinity over a certain threshold level

Helper CD4(+) T lymphocytes can be divided into two subsets, Th1 and Th2. T he types of Th subsets activated during the adaptive immune response induct ion determine the efficacy of immune responses against the antigens introdu ced. Selective differentiation of subsets of CD4(+) T lymphocytes has been known to be influenced by several factors, such as the cytokine environment around the T cells, the specificity of antigen recognition by the T cell r eceptor, the expression of costimulatory molecules, and/or the dose of the antigen applied to stimulate the T calls. In this study, we tried to determ ine the influence of the antigen dose on the selective priming of T lymphoc ytes when an inefficient antigen was applied since all the conclusions draw n from previous experiments were based on experiments with immune systems w hich responded well against the antigens introduced. When the recombinant h en egg-white lysozyme (HEL) was used to stimulate immune responses in HEL l ow-responder C57BL/6 mice, dose-dependent selective priming of immune respo nses was not observed. However, when the variant antigen, which had been ch aracterized as an efficient antigen in anti-HEL immune response induction i n the low-responder mice, was applied, dose-dependent selective priming of Th immune responses was clearly demonstrated. These results suggested that dose-dependent selective priming of Th immune responses could be achieved o nly by the antigens with an affinity over a certain level.