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Monocyte produced burst-promoting activity after stimulation with lymphokine
Normal monocytes were stimulated by lymphokine(s) from a homogenous population of malignant T cells of the helper phenotype (OKT 3+/4+/6-/8-/11+). The resultant monocyte-conditioned medium after stimulation with T cell-conditioned medium (M-CM+) was assayed for burst-promoting activity. The number of burst-forming units-erythriod (BFU-E) in methylcellulose cultures of normal human nonadherent peripheral blood cells increased by nearly threefold in the presence of 5% M-CM+. This activity was lost after the conditioned medium was boiled for 20 min. The addition of 5% conditioned medium (CM) from unstimulated monocytes did not significantly increase BFU-E proliferation. We conclude that lymphokine(s) from malignant T cells of the helper phenotype stimulate normal monocytes to produce a heat-sensitive monokine that increases BFU-E proliferation.
Normal monocytes were stimulated by lymphokine(s) from a homogenous population of malignant T cells of the helper phenotype (OKT 3+/4+/6-/8-/11+). The resultant monocyte-conditioned medium after stimulation with T cell-conditioned medium (M-CM+) was assayed for burst-promoting activity. The number of burst-forming units-erythriod (BFU-E) in methylcellulose cultures of normal human nonadherent peripheral blood cells increased by nearly threefold in the presence of 5% M-CM+. This activity was lost after the conditioned medium was boiled for 20 min. The addition of 5% conditioned medium (CM) from unstimulated monocytes did not significantly increase BFU-E proliferation. We conclude that lymphokine(s) from malignant T cells of the helper phenotype stimulate normal monocytes to produce a heat-sensitive monokine that increases BFU-E proliferation.