Identification of a distinct low-affinity receptor for human interleukin-4 on pre-B cells

• Published in: Blood 1993-06, Vol.81 (11), p.2998-3005
• Main Authors: FANSLOW, W. C, SPRIGGS, M. K, RAUCH, C. T, CLIFFORD, K. N, MACDUFF, B. M, ZIEGLER, S. F, SCHOOLEY, K. A, MOHLER, K. M, MARCH, C. J, ARMITAGE, R. J
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analysis of the immune response. Humoral and cellular immunity; Antibodies, Monoclonal - immunology; B-Lymphocytes - chemistry; Biological and medical sciences; Cross-Linking Reagents; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Gene Expression; Humans; Immunobiology; Interleukin-4 - metabolism; Lymphokines, interleukins ( function, expression); Molecular Sequence Data; Receptors, Interleukin-4; Receptors, Mitogen - chemistry; Receptors, Mitogen - immunology; Regulatory factors and their cellular receptors; RNA, Messenger - genetics; Solubility
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V81.11.2998.2998

Biotinylated interleukin-4 (IL-4) was used to examine IL-4 receptor (IL-4R) expression on a range of human B-cell lines by flow cytometry. Using high concentrations of biotinylated IL-4, we have identified a novel low-affinity IL-4 receptor expressed at high levels on pre-B lines. Expression of this low-affinity receptor did not correlate with detected mRNA levels for the previously cloned receptor or with reactivity of two anti-human IL-4R monoclonal antibodies (MoAb). Radiolabeled IL-4 cross-linking studies using pre-B lines showed a doublet of 65 to 75 Kd in contrast to the 110- to 130-Kd molecule detected on cells expressing the cloned IL-4R. A soluble IL-4 binding protein (IL-4bp) was purified from the supernatants of three pre-B lines expressing the low-affinity receptor on their surface. IL-4bp could block both IL-4-mediated CD23 induction on tonsil B cells and IL-4-induced inhibition of proliferation of the pre-B line JM1. Partial N-terminal amino acid sequence was obtained from purified IL-4bp that confirmed this protein to be novel. A 12 amino acid peptide based on the IL-4bp sequence was used to produce a polyclonal antiserum that was reactive with purified IL-4bp, and also bound to the surface of pre-B cells but not to murine CTLL cells transfected with the human IL-4R. Blocking MoAb against the previously characterized high-affinity receptor inhibited IL-4-mediated proliferation of hIL-4R+ CTLL cells but had no effect on IL-4-induced inhibition of JM1 cell proliferation, and only partially inhibited IL-4-mediated CD23 and sIgM induction and proliferation of tonsil B cells. The data presented here provide evidence for a novel cell-surface expressed low-affinity IL-4R that also exists as a biologically active soluble IL-4 binding protein.