Anti-I-J alloantisera elicited by immunization of B10.A (3R)(I-Jb) mice with bone marrow-derived macrophages from B10.A (5R)(I-Jk) mice.

In this paper we describe production of alloantisera specific for determinants encoded by I-J gene loci expressed on macrophages. B10.A(3R) (l-J^b) mice were hyperimmunized with pure populations of macrophages grown in vitro from bone marrow stem cells of congenic B10.A(5R) mice. The antisera contained predominantly IgM antibody that was non-adherent to protein-A-Sepharose with a minor component of IgGI, and IgG2a antibodies that were adherent to protein.A-Sepharose. The protein- A non-adherent antibody completely blocked the in vitro generation of humoral immune responses to sheep erythrocytes by spleen cell from B10.A(5R) mice and from inbred strains that share the I-J^k haplotypes, but did not alter the responses of spleen cells of the I-J^b haplotype. In the presence of complement. both protein-A adherent and protein-A non-adherent antibodies eliminated the capacity of B10.A(5R) spleen cells to generate humoral and proliferative responses, but the functional activity of B10.A(3R) cells was unaffected. These data indicate the I-J^k specificity of the antisera. The capacity of the anti-macrophage antibody to block humoral immune induction was removed by absorption with bone marrow-derived macrophages from B10.A(5R) mice, but not from B10.A(3R) mice. Further, the B10.A(5R) macrophages completely restored the humoral responses of antibody- and complement-treated B10.A(5R) spleen cells, but B10.A(3R) macrophages showed only partial restoration that was consistent with a factor-mediated allogeneic effect. These data demonstrate the specificity of our anti-I-J sera for macrophages and indicate that bone marrow-derived macrophages express surface I-J encoded molecules. [ABSTRACT FROM AUTHOR]