Cloning of early erythroid and mixed myeloid/erythroid human bone marrow progenitor cells: comparison of different sources of burst-promoting activity (BPA).
The ability of conditioned media from the 5637 cell line and human placenta (HPCM) to stimulate the in vitro growth of human early erythroid and mixed myeloid/erythroid clones was tested and compared to phytohemagglutinin-stimulated leukocyte supernatants (PHA-LCM). Both 5637 supernatant and PHA-LCM were equally effective with a linear dose-response relationship. HPCM at various concentrations did not exhibit burst-promoting activity (BPA). Thus, "pluripoietin"-containing media provide a large-scale source of BPA similar in its biological activity to standard sources used for studying human hematopoiesis in vitro.