EFFICIENCY OF HUMAN HLA-MISMATCHED CD34(-VITRO HEMATOPOIESIS IN ALLOGENEIC LONG-TERM MARROW CULTURES() CELLS FROM UNRELATED DONORS IN ESTABLISHING IN)

We have examined the capacity of highly purified human CD34(+) marrow cell isolates from unrelated, HLA-mismatched donors to establish in vi tro hematopoiesis on recipient marrow stromal cells in 2-stage hematop oietic long-term marrow cultures (H-LTMC). HLA-typing of both peripher al blood mononuclear cells and CD34(+) marrow cells was performed for both HLA class T and KLA class II antigens for eight healthy individua ls. Significant antigenic mismatches for these molecules ranged from t hree to six antigens for each recipient-donor pair. Comparison of MHC antigen expression by peripheral blood cells and CD34(+) marrow cell i solates confirmed the presence of identical HLA-A, -B, and -C, and -DR specificities on the surface of these cells. Typing of -DQ specificit ies, however, was not consistently reactive on CD34(+) cells. The grea ter than or equal to 20% plating efficiency of purified CD34(+) cells for BFU-E, CFU-GM, and CFU-MIX allowed us to use inoculum doses of 10( 3), 10(4), and 10(5) cells to determine the efficiency of allogeneic C D34(+) cells in achieving in vitro engraftment and the establishment o f hematopoiesis in H-LTMC. Engraftment of adherent BFU-E, CFU-GM, and CFU-MIX was equally efficient for autologous and allogeneic CD34(+) ce lls. In vitro hematopoiesis reflected by the cumulative recoveries of progenitor cells over time was also equivalent for allogeneic and auto logous CD34(+) cells. These results demonstrate that highly purified, HLA-mismatched CD34(+) marrow cells proliferate and establish in vitro hematopoiesis as efficiently as autologous cells in marrow derived st romal cell cultures and confirm that interactions between stromal cell s and highly purified CD34(+), DR(-), and CD34(+), DR(+) marrow cell i solates are not MHC-restricted.