THE ROLE OF MACROPHAGES IN ANTIGEN PRESENTATION AND T-CELL TOLERANCE

Bone marrow derived cells (dendritic cells, macrophages and B cells) a re involved in antigen presentation and T cell tolerance. However, the precise functions of each cell type remain unclear. To determine the role of macrophages we produced transgenic mice expressing I-E molecul es only on macrophages, by introducing the hybrid gene containing the colony stimulating factor-1 (CSF-1) receptor promoter region and the s tructural gene encoding E(alpha)d into C57BL/6 mice. In these mice I-E restricted antigen presentation and T cell priming were impaired. Wit h respect to T cell tolerance, I-E reactive T cells were anergized but not clonally deleted. These results clearly demonstrate that macropha ges by themselves are defective in efficient I-E restricted antigen pr esentation, so that T cells exposed to antigens expressed on macrophag es are led to anergy.