A HIGH PERCENTAGE OF HLA-DQ(-DR(+) MONONUCLEAR-CELLS IS ASSOCIATED WITH A LOW INCIDENCE OF ACUTE GRAFT-VERSUS-HOST DISEASE AFTER ALLOGENEICBONE-MARROW TRANSPLANTATION (BMT) IN CHILDREN() AND HLA)

In order to discover some biological markers of acute graft-versus-hos t disease (aGVHD), we have studied the percentage of peripheral monocy tes and T lymphocytes bearing HLA-DR and HLA-DQ class II molecules. Th is study included 25 allogeneic BMT in children, either with (n = 10) or without (n = 15) aGVHD. Within 2 months after transplantation, a hi gher percentage of DQ(+) and DR(+) monocytes and of DQ(+) T lymphocyte s was observed in patients without aGVHD compared with patients with a GVHD. The most discriminating marker was the strong increase in the pe rcentage of DQ(+) monocytes in patients without aGVHD (P = 0.001). In a sequential study, we observed a low percentage of DQ(+) and DR(+) pe ripheral blood mononuclear cells (PBMC) as long as the clinical manife stations of aGVHD continued. We speculate if the modulation of DQ and DR molecules on PBMC after BMT is a consequence of the action of some lymphokines, and if it plays a role in the regulation of the acute GVH reaction. We conclude that MHC class II molecules on peripheral monon uclear cells may be reliable biological markers for the diagnosis of a GVHD.