BETA(2)-MICROGLOBULIN-DEPENDENT T-CELLS ARE NOT NECESSARY FOR ALLOANTIGEN-INDUCED TH2 RESPONSES AFTER NEONATAL INDUCTION OF LYMPHOID CHIMERISM IN MICE

We have analyzed the requirement for beta(2)-microglobulin (beta(2)m)- dependent T cells in the generation of allogeneic Th2 responses in viv o. A neonatal injection of semiallogeneic cells in BALB/c mice induces a state of chimerism that promotes the differentiation of donor-speci fic CD4(+) T cells toward the Th2 phenotype, Polyclonal T-B cell inter actions occur in this model between host Th2 and donor B cells, result ing in the production of IgE Abs, IgE production and Th2-priming are c ritically dependent upon the early production of IL-4, Our data in the present paper demonstrate that: 1) IgE synthesis and the up-regulatio n of MHC class II and CD23 molecules on B cells are independent of bet a(2)m expression in the host, 2) no difference in the induction of CD4 alloreactive Th2 cells could be observed between beta 2(-/-) and thei r wild-type control littermates when Th2-priming was measured in adult mice, and 3) the Th2 response and IgE production is induced in the co mplete absence of beta(2)-dependent T cells both in the host and in th e inoculum, Therefore, using a variety of assays, we could not demonst rate diminished responses in mice with a disrupted beta(2)m gene in th is model of Th2-mediated allogeneic interaction, indicating that beta( 2)m-dependent NK1.1(+) and CD8(+) T cells are not required for the gen eration of alloreactive Th2 responses in vivo.