A soluble, high-affinity, interleukin-4-binding protein is present in the biological fluids of mice

Rafael Fernandez-Botran, Ellen S. Vitetta

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

Cytokines such as interleukin 4 (IL-4) play a key role in the regulation of immune responses, but little is known about how their multiple activities are regulated in vivo. In this report, we demonstrate that an IL-4-binding protein (IL-4BP) is constitutively present in the biological fluids of mice (serum, ascites fluid, and urine). Binding of 125I-labeled IL-4 to the IL-4BP is specific and saturable and can be inhibited by an excess of unlabeled IL-4 but not IL-2. The IL-4BP binds IL-4 with an affinity similar to that reported for the cellular IL-4 receptor (K(d) ≃ 7 x 10-11 M) and has a molecular mass of 30-40 kDa and pI values of 3.6-4.8. IL-4BP-containing biological fluids or purified IL-4BP competitively inhibit the binding of 125I-labeled IL-4 to mouse T or B cells and inhibit the biological activity of IL-4 but not IL-2. The serum levels of IL-4BP in severe combined immunodeficiency (SCID) mice are lower than those of normal mice. The above findings suggest that IL-4BP plays an important immunoregulatory role in vivo.

Original languageEnglish (US)
Pages (from-to)4202-4206
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number11
DOIs
StatePublished - 1990

Keywords

  • immunoregulation
  • interleukin 4 receptor

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'A soluble, high-affinity, interleukin-4-binding protein is present in the biological fluids of mice'. Together they form a unique fingerprint.

Cite this