In vitro hemopoiesis in human micro long-term bone marrow cultures recharged with either allogeneic, T-cell-depleted allogeneic, or syngeneic bone marrow cells.

The production of granulocyte-macrophage colony-forming cells (GM-CFC) and the proliferation period in human long-term bone marrow cultures are inferior to murine cultures. There is also evidence that recharge of the cultures after establishing confluent stromal layers will not greatly improve myelopoiesis. Data in the literature indicate that PHA-responsive T lymphocytes persist for up to 5 weeks in human but not in murine long-term marrow cultures. We therefore analyzed the effects of recharging micro long-term bone marrow cultures with bone marrow cell samples depleted by T lymphocytes. Depletion was performed in a complement-mediated cytotoxicity assay by applying the monoclonal antibody CAMPATH-1. Our data show that regardless of whether T cells were removed only at recharge, at both initiation and recharge, or only at initiation, obvious enhancement could neither be achieved in the GM-CFC production nor in the proliferation period. Furthermore, no advantage was seen when using syngeneic marrow cells. We conclude that in allogeneic long-term marrow cultures hemopoiesis is not limited by immunological incompatibilities.