Human peripheral blood erythroid burst forming unit (BFU(E)): evidence against T-lymphocyte requirement for proliferation in vitro.

Erythroid burst-forming units (BFU(E)) are proliferative cells which may be precursors of the erythroid colony-forming unit (CFU(E)). To examine the role of T lymphocytes in the proliferation and/or differentiation of human blood BFU(E), the effect of purified T lymphocytes on erythroid colony (EC) formation by purified null cells was examined in vitro. Lymphocyte subpopulations were prepared by Ficoll-Hypaque centrifugation, immunoadsorbent chromatography, and sheep red blood cell rosetting after removal of monocytes by adherence to plastic. Cultures of isolated B, T, or null lymphocytes alone revealed that BFU(E) were present in the null cell fraction. Addition of isolated B and/or T lymphocytes in various ratios to null cells failed to influence the number or size of EC formed. These results indicate that normal human circulating BFU(E) are contained in the null cell fraction of peripheral blood lymphocytes and do not require T lymphocytes for normal growth and differentiation in vitro.