Human basophils express interleukin-4 receptors

Abstract

Interleukin-4 (IL-4), a multipotential lymphokine reputed to play an important role in the regulation of immune responses, interacts with a variety of hemopoietic target cells through specific cell surface membrane receptors. The present study was designed to investigate whether human basophils express IL-4 binding sites. For this purpose, basophils were enriched to homogeneity (93% and 98% purity, respectively) from the peripheral blood of two chronic granulocytic leukemia (CGL) donors using a cocktail of monoclonal antibodies (MoAbs) and complement. Purified basophils bound 125I-radiolabeled recombinant human (rh) IL-4 in a specific manner. Quantitative binding studies and Scatchard plot analysis revealed the presence of a single class of high affinity IL-4 binding sites (280 ± 40 sites per cell in donor 1 and 640 ± 45 sites per cell in donor 2) with an apparent dissociation constant, kd, of 7.12 × 10-11 ± 2.29 × 10-11 and 9.55 ± 3.5 × 10-11 mol/L, respectively. KU812-F, a human basophil precursor cell line, was found to express a single class of 810 to 1,500 high affinity IL-4 binding sites with a kd of 2.63 to 5.54 × 10-10 mol/L. No change in the numbers or binding constants of IL-4 receptors was found after exposure of KU812-F cells to rhlL-3 (a potent activator of basophils) for 60 minutes. No effect of rhlL-4 on 3H-thymidine uptake, release or synthesis of histamine, or expression of basophil differentiation antigens (Bsp-1, CD11b, CD25, CD40, CD54) on primary human CGL basophils or KU812-F cells was observed. © 1990 by The American Society of Hematology.