Article: article from journal or magazin.
Characterization of human fibroleukin, a fibrinogen-like protein secreted by T lymphocytes.
Journal of Immunology
Publication types: Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, P.H.S.
We have recently cloned the human homologue of the murine pT49 cDNA (hpT49h), a transcript encoding a protein homologous to the beta- and gamma-chains of fibrinogen. Here, we report the identification of the hpT49h gene product using mAbs generated against a peptide corresponding to the carboxyl-terminal end of the deduced protein and a recombinant protein fragment expressed in Escherichia coli. mAbs 23A6, 7B12, and 3F4 specifically recognized a protein of 70 kDa in reducing SDS-PAGE in the culture supernatant of 293T cells transiently transfected with the full length hpT49h cDNA and freshly isolated PBMC. Under nonreducing conditions, the material migrated with a molecular mass of 250 to 300 kDa, indicating that the 70-kDa protein forms a disulfide bonded complex. Because of its homology with fibrinogen, we have termed this protein fibroleukin. Fibroleukin is spontaneously secreted in vitro by freshly isolated CD4+ and CD8+ T lymphocytes. RT-PCR analysis revealed preferential expression of fibroleukin mRNA in memory T lymphocytes (CD3+/CD45R0+) compared with naive T lymphocytes (CD3+/CD45RA+). Fibroleukin production by PBMC was rapidly lost in culture. Production could be partially maintained in the presence of IFN-gamma, while T lymphocyte activation had no effect. To demonstrate fibroleukin production in vivo, we analyzed colon mucosa by immunohistology. Fibroleukin staining was detected in the extracellular matrix of the T lymphocyte-rich upper portion of the lamina propria mucosa. While the exact function of fibroleukin remains to be defined, these data suggest that fibroleukin may play a role in physiologic lymphocyte functions at mucosal sites.
Amino Acid Sequence, Antibodies, Monoclonal/biosynthesis, Antigens, CD3/analysis, Antigens, CD4/analysis, CD8-Positive T-Lymphocytes/secretion, Cell Line, Cells, Cultured, Colon/metabolism, Disulfides/metabolism, Fibrinogen/biosynthesis, Fibrinogen/chemistry, Fibrinogen/</QualifierName> <QualifierName MajorTopicYN="Y">, Gene Expression/immunology, Humans, Immunologic Memory, Interphase/immunology, Intestinal Mucosa/metabolism, Kidney/cytology, Macromolecular Substances, Molecular Sequence Data, RNA, Messenger/biosynthesis, T-Lymphocyte Subsets/chemistry, T-Lymphocyte Subsets/immunology
Web of science
Last modification date