Human basophils express interleukin-4 receptors.
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 x 10(-11) +/- 2.29 x 10(-11) and 9.55 +/- 3.5 x 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 x 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 rhIL-3 (a potent activator of basophils) for 60 minutes. No effect of rhIL-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.
Valent
P
P
I. Medical Department, University of Vienna, Austria.
Besemer
J
J
Kishi
K
K
Di Padova
F
F
Geissler
K
K
Lechner
K
K
Bettelheim
P
P
D000954:Antigens, Surface / Q000378:metabolism; D001491:Basophils / Q000378:metabolism / Q000648:ultrastructure*; D002460:Cell Line; D006632:Histamine / Q000378:metabolism; D006636:Histamine Release / Q000187:drug effects; D006801:Humans; D007457:Iodine Radioisotopes; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism / Q000473:pathology; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen / Q000502:physiology*; D013234:Stem Cells / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure
D000954:Antigens, Surface; D007457:Iodine Radioisotopes; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen; D006632:Histamine