FLUORESCENT PROBE ASSAY OF EARLY MIXED LYMPHOCYTE REACTION TO PREDICT ALLOGRAFT SURVIVAL IN MICE

Abstract
A rapid fluorescent probe assay of mixed lymphocyte reactivity has permitted prediction of allograft survival in mice. The assay is based on detection of early membrane events in stimulated cells by decreased fluorescence intensity of cell-bound N-phenyl-1-napthylamine (NPN) 30 min after allogenic cell interaction. The NPN-mixed-lymphocyte reaction (NPN-MLR) detected antigenic differences coded for by the whole H-2 complex or by the I region but not by the M locus. The probe assay correlated better with graft survival than did conventional 3H-thymidine assay, which also detects differences at the M locus that are less relevant to allograft rejection. Investigation of the cell types needed to obtain the response detected by the NPN-MLR assay revealed a requirement for mature T cells and plastic-surface-adherent monocytes and macrophages in the responding cell population. The monocytes and macrophages had an essential role in the generation of soluble factors that mediated the NPN-detected response. The NPN-MLR assay offers a reliable, rapid test of recipient-donor compatibility for allograft survival, and a system for studying early events in allogeneic cell interaction.