Bone marrow stromal cell lines with lymphopoietic activity express high levels of a pre-B neoplasia-associated molecule.

Bone marrow stromal cell lines have been isolated that directly support B lymphopoiesis in vitro. Single B-lineage precursors proliferate and differentiate on certain of these stromal cell lines to establish long-term B-lineage cultures. These lymphopoietic stromal cells produce novel soluble factors that support proliferation of in vitro established pre-B cell populations. Lymphoid populations established on lymphopoietic stromal cell lines lack surface Ig-bearing cells, but give rise to surface Ig+ cells when transferred to mixed bone marrow feeder layers. Several stromal lines expressed a B-lineage neoplasia marker detected by the monoclonal antibody MAb6C3. Remarkably, only the 6C3Aghi stromal lines supported long-term proliferation of B-lineage cells. We propose that the 6C3 antigen-bearing molecule may play a role in stromal cell-dependent, pre-B cell proliferation, as well as in neoplastic proliferation of pre-B leukemias.