TISSUE DISTRIBUTION AND POLYMORPHISM OF MINOR HISTOCOMPATIBILITY ANTIGENS INVOLVED IN GVHR

A graft-vs-host reaction (GVHR) develops after major histocompatibilit y complex (MHC)-compatible bone marrow-transplantation. In the genetic combination studied, B10.D2 donor cells differed from those of (DBA/2 x B10.D2)F-1 mice for multiple DBA/2 minor histocompatibility antigen s (mHAg) and minor lymphocyte stimulating (Mls) antigens. We investiga ted the distribution and the cell type expression of mHAg in tissues t hat were potential GVHR targets, by means of specific T-cell clones de rived from mice undergoing reaction. The T-cell clones studied had a C D4+ phenotype and recognized 12 distinct mHAg that were not be product of the Mls-1(a) gene and that were presented predominantly in associa tion with MHC class II A molecules. Our results indicate that DBA/2 al leles coding for mHAg are frequent in both laboratory and geographical ly unrelated wild mice. Each mHAg displays an individual pattern of ex pression on cells present in thymus, skin, gut, and liver. In addition , chimeric mice and established cell lines allowed the identification of cell types expressing mHAg. We found that most mHAg are present on lymphoid and monocyte-macrophage cells, whereas one, distinguished by its absence from lymphoid cells and damaged tissues, is expressed by m onocyte-macrophage cells.