A subpopulation of cultured human promyelocytic leukemia cells (HL-60) displays the formyl peptide chemotactic receptor.

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The chemotactic peptide N-formyl-Nle-Leu-Phe-Nle-Tyr(125I)-Lys (formyl 125I-peptide) binds in a saturable manner to human promyelocytic leukemia cells (HL-60) grown in suspension culture. The binding is of high affinity (50% binding at 0.4--0.75 nM), is rapid (half-time at 22 degrees C = 10 min), is enhanced by divalent cations, but is poorly reversible. These characteristics are similar to those of the formyl peptide chemotactic receptor on human peripheral blood neutrophils. The relative potencies of a series of synthetic peptides in inhibiting binding to the HL-60 cell receptor correlate closely with their potencies in inhibiting binding to the peripheral neutrophil receptor. However, whereas all peripheral human neutrophils display the receptor, only a subpopulation of the cultured cells will bind and internalize tetramethylrhodamine-labeled N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys. This subpopulation is distinct from the rest of the culture, displays morphological characteristics typical of well-differentiated promyelocytes, and appears to account for all of the measured fromyl 125I-peptide binding. Binding of both 125I-labeled and tetramethylrhodamine-labeled formyl peptide increases in response to treatment of the culture with polar compounds that induce cell differentiation. Cells from the differentiated culture demonstrate a chemotactic response to N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys, whereas cells from the undifferentiated culture do not.

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