Restriction fragment length polymorphism analysis with a cross-reactive HLA class II DR-beta gene probe for the detection of engraftment of MHC-mismatched marrow in the rhesus monkey.

Our interest in MHC-mismatched allogeneic bone marrow transplantation (BMT) in the rhesus monkey prompted us to investigate restriction fragment length polymorphism analysis as a means for detecting lymphohematopoietic chimerism in the primate. A human MHC (HLA) class II DR beta gene cDNA probe was tested on rhesus peripheral blood mononuclear cell DNA digested with any of three restriction enzymes. We found that (1) the human DR beta probe hybridized to as many as 15 restriction fragments per rhesus DNA sample, suggesting cross-hybridization at more than one locus of rhesus MHC class II beta genes; (2) restriction fragment length polymorphisms were common among outbred monkeys as a result of class II beta gene polymorphisms and would be sufficient for chimerism detection in the majority of random pairs of outbred monkeys utilizing only a single restriction enzyme (Bgl II); and (3) sensitivity (5-10% chimerism) was comparable to that reported for restriction fragment length polymorphism assays utilizing non-MHC probes in clinical HLA-identical BMT. Utility of the assay was demonstrated in a preliminary series of experiments in rhesus monkeys conditioned with mixed T cell-depleted MHC-mismatched allogeneic plus T cell-depleted autologous BMT with or without cardiac allograft implantation.