Selective expression of class-II MHC antigens during hemopoietic differentiation

Human multipotential or "mixed" bone marrow colony-forming cells and lineage-restricted colony-forming progenitors have been analyzed by cell sorting (FACS) using a series of monoclonal antibodies. The latter all react with monomorphic class-II MHC glycoprotein determinants but differ in their reactivity or cross-reactivity with products of different loci, i.e., SB (DP), DC (DQ), DR. The results confirm that very few progenitor cells detectably express DC. Anti-DR monoclonals varied in their reactivity with progenitor cells. The majority of progenitors in all lineage categories express determinants that are shared or cross-reactive between DR and SB while fewer progenitors can be shown to bind antibodies specific for DR or SB.