Molecular cloning of a macrophage-derived, interferon-inducible secreted immunoglobulin-binding protein.
We describe the molecular cloning of a 1803-bp cDNA coding for a product termed interferon-induced immunoglobulin-binding protein (IIBP) from a library of IFN-alpha-induced primary bone marrow macrophages. The open reading frame encodes a protein of 26-kDa containing two immunoglobulin-like and one Fc receptor-like domain. Due to the constitutive release of low amounts of IFN-beta, the IIBP mRNA is already present in macrophage-colony-stimulating factor-cultured macrophages. Its expression could be blocked in the presence of either anti-IFN-beta or interleukin-4, which down-regulates the endogenous IFN-beta production. Upon addition of rIFN-alpha4 a 3-5-fold superinduction of IIBP mRNA was observed. Rat monoclonal antibodies detected a protein of the predicted size exclusively in cell culture supernatants of primary bone marrow macrophages and a B-cell line. In immunoprecipitation experiments an unknown 30-kDa protein co-precipitated. The secreted IIBP showed considerable binding to nonspecific rat IgG2a and could be precipitated using mouse IgG2a, IgG2b and IgG3 antibodies of irrelevant specificities, indicating that this gene product is a novel secreted immunoglobulin-binding protein with a new IgG isotype binding pattern that differs to that of known Fc receptors.
Nickolaus
P
P
Institute for Cell Biology, Department of Immunology, University of Tübingen, Germany. peter.nickolaus@uni-tuebingen.de
Rammensee
H G
HG
Zawatzky
R
R
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001854:Bone Marrow Cells / Q000187:drug effects / Q000276:immunology; D002352:Carrier Proteins / Q000235:genetics*; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005786:Gene Expression Regulation; D007370:Interferon Type I / Q000276:immunology / Q000494:pharmacology; D016899:Interferon-beta / Q000276:immunology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018076:DNA, Complementary; D007370:Interferon Type I; D011506:Proteins; D011994:Recombinant Proteins; C119675:Sirpb1a protein, mouse; D016899:Interferon-beta