DELETION OF BONE-MARROW STROMAL CELL ANTIGEN-1 (CD157) GENE IMPAIRED SYSTEMIC THYMUS INDEPENDENT-2 ANTIGEN-INDUCED IGG3 AND MUCOSAL TD ANTIGEN-ELICITED IGA RESPONSES

Bone marrow stromal cell Ag-1 (BST-1; CD157)-deficient mice were gener ated to examine the immunologic roles of the molecule in vivo. In BST- 1(-/-) mice, the development of peritoneal B-1 cells was delayed, and CD38(low/-) B-lineage cells were increased in the bone marrow and sple en. Partial impairment of thymus-independent (TI-2) and thymus-depende nt (TD) Ag-specific immune responses was noted in the systemic and muc osal compartments of BST-1-/- mice, respectively. Although serum Ig Be vels as well as TD and TI-1 Ag-specific systemic immune responses were normal, the TI-2 Ag-induced IgG3 response was selectively impaired. O ral immunization of PST-1(-/-) mice with cholera toxin, a potent TD Ag for the induction of IgA response, resulted in the poor production of Ag-specific Abs at the intestinal mucosa accompanied by the reduced n umber of Ag-specific IgA-producing cells in the lamina propria. These results indicate that BST-I has roles in B cell development and Bb pro duction in vivo.