Bone marrow-derived macrophage as accessory cells in antigen-induced T cell proliferation. H-2I region requirements for L-glutamic60-L-alanine30-L-tyrosine10 response.

Marrow stem cells cultured with L cell-conditioned medium were used to produce large numbers of macrophages free of contaminating lymphoid cells or granulocytes. Experiments were performed by using these bone marrow-derived macrophages (BMDM) as antigen-presenting cells (APC) for the terpolymer antigen L-glutamic60-L-alanine30-L-tyrosine10 (GAT). By using antigen-specific T cell proliferation, it was demonstrated that BMDM were equal to splenic macrophages in their capacity to present GAT. Furthermore, when BMDM were pretreated with alloantibodies specific for Ia antigens of the I-A subregion, the T cell proliferative response to GAT was inhibited. The I-A subregion is known to be the site of Ir gene regulation of the GAT response, and antibodies to other subregions had no inhibitory effect. Monoclonal antibodies recognizing a beta-chain product of the I-A subregion (Ia. 17) also inhibited the BMDM from effective antigen presentation. These results were similar to those obtained with purified splenic macrophages.