[Costimulatory molecule expression on allergen-stimulated PBMC in cedar pollinosis subjects]

B7-1 (CD80) and B7-2 (CD86) play important roles in the differentiation of Th1 and Th2 phenotypes. CD40-CD40L interaction supports the expression of CD80 and CD86 on antigen-presenting cells. Blocking studies suggest these molecules also play important roles in sensitization to a cedar pollen antigen by, but very few studies have concerned their effects on subsequent induction by antigens. We investigated the roles of CD80, CD86, and CD40 in the differentiation of Th1 and Th2 subsets after stimulation with the antigen in subjects with cedar pollinosis. Peripheral blood mononuclear cells (PBMC) were isolated from 12 subjects with pollinosis and 11 healthy controls and stimulated with cedar pollen extract. After in vitro stimulation, CD80, CD86, and CD40 expression on CD19+ cells were analyzed by flow cytometry. The production of type 1 and type 2 cytokines in culture supernatants was measured by FLISA. Proliferation studies were conducted in the presence or absence of anti-CD40 or CD86 mAbs. After in vitro stimulation, CD86 and CD40 were significantly up-regulated following stimulation in pollinosis subjects (p = 0.02 and p = 0.04). A significantly higher level of IL-5 (p = 0.02) was produced by PBMC of pollinosis subjects than by those of controls. Allergen-induced proliferation and IL-5 production of PBMC of pollinosis subjects were inhibited by anti-CD86 mAb but not CD40 mAb. These results indicate that the Th2 response predominated in pollinosis subjects and that CD86 rather than CD80 may be the costimulatory molecule involved in the allergen-induced activation of PBMC.