A high percentage of HLA‐DQ+ and HLA‐DR+ mononuclear cells is associated with a low incidence of acute graft‐versus‐host disease after allogeneic bone marrow transplantation (BMT) in children
In order to discover some biological markers of acute graft‐versus‐host disease (aGVHD), we have studied the percentage of peripheral monocytes and T lymphocytes bearing HLA‐DR and HLA‐DQ class II molecules. This study included 25 aliogeneic BMT in children, cither with (n= 10) or without (n= 15) aGVHD. Within 2 months after transplantation, a higher percentage of DQ+ and DR+ monocytes and of DQ+ T lymphocytes was observed in patients without aGVHD compared with patients with aGVHD. The most discriminating marker was the strong increase in the percentage of DO+ monocytes in patients without aGVHD (P= 0·001). In a sequential study, we observed a low percentage of DQ+ and DR+ peripheral blood mononuclear cells (PBMC) as long as the clinical manifestations 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 mononuclear cells may be reliable biological markers for the diagnosis of aGVHD.