REGULATION OF HUMAN PERIPHERAL-BLOOD ERYTHROID BURST-FORMING UNIT GROWTH BY LYMPHOCYTES-T AND LYMPHOCYTE-T SUBPOPULATIONS DEFINED BY OKT4 AND OKT8 MONOCLONAL-ANTIBODIES

  • 1 January 1985
    • journal article
    • research article
    • Vol. 65  (2) , 456-463
Abstract
To reexamine the influence that T lymphocytes have on the regulation of human peripheral blood burst-forming unit (BFU-E) proliferation in the absence of a statistically significant number of monocytes, very low numbers (3-10 .times. 103/ml) of a null cell fraction highly enriched for BFU-E were cultured alone and in the presence of 5 .times. 105 sheep erythrocyte-purified, autologous T lymphocytes in a methylcellulose culture system containing erythropoietin. T lymphocytes consistently enhanced the growth of BFU-E from the null cell fraction, as reflected in both their number and size. Irradiation of T lymphocytes prior to coculture with null cells markedly reduced this enhancement, strongly suggesting that T lymphocytes synthesize erythroid burst-promoting factors (BPA). To determine whether there were functional differences between the 2 major T lymphocyte populations as defined by OKT4 (T helper/inducer) and OKT8 (T suppressor/cytotoxic) murine monoclonal antibodies to stimulate the growth of BFU-E, both T cell subpopulations were isolated by negative (panning) or positive (fluorescence-activated cell sorting) selection and cocultured with null cells. No statistically significant differences emerged between unseparated, OKT4+ and OKT8+ T lymphocyte in their ability to stimulate the growth of BFU-E. T lymphocytes apparently are a major population of BPA-producing cells and further that OKT4+ and OKT8+ T lymphocytes equally elaborate these factors.