Identification of a distinct low-affinity receptor for human interleukin-4 on pre-B cells.
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.
Fanslow
W C
WC
Immunex Research and Development Corp., Seattle, WA 98101.
Spriggs
M K
MK
Rauch
C T
CT
Clifford
K N
KN
Macduff
B M
BM
Ziegler
S F
SF
Schooley
K A
KA
Mohler
K M
KM
March
C J
CJ
Armitage
R J
RJ
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D001402:B-Lymphocytes / Q000737:chemistry*; D003432:Cross-Linking Reagents; D015870:Gene Expression; D006801:Humans; D015847:Interleukin-4 / Q000378:metabolism*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen / Q000737:chemistry* / Q000276:immunology; D012995:Solubility
D000911:Antibodies, Monoclonal; D003432:Cross-Linking Reagents; D012333:RNA, Messenger; D019948:Receptors, Interleukin-4; D011975:Receptors, Mitogen; D015847:Interleukin-4