Induction of antigen presentation capacity and MHC class II gene expression in bone marrow macrophages derived from...

In this study we show that bone marrow macrophages (BMM phi), derived by culturing bone marrow stem cells in macrophage colony-stimulating factor (M-CSF)-containing medium, and activated by an optimal dose of interferon-gamma, selectively interacted with only some out of a group of protein antigen-specific T cell clones as measured by antigen-specific T cell proliferation. Antibody inhibition experiments employing monoclonal anti-CD4 antibodies suggest that the failure of various T cell lines to cooperate with BMM phi might be due to a low avidity of the interaction between these T cells and the accessory cells. We further show that BMC that were allowed to mature in the presence of recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) developed into highly efficient accessory cells leading to antigen-specific activation of all T cell clones tested. No correlation was found with the level of expression of MHC class II genes induced in GM-CSF-treated BMM phi, although significant amounts of transcripts of A alpha, A beta and of the non MHC-encoded invariant gamma-chain were detected by Northern blot analysis.