Molecular characterization of human 4Ig-B7-H3, a member of the B7 family with four Ig-like domains.
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Steinberger P, Majdic O, Derdak SV, Pfistershammer K, Kirchberger S, Klauser C, Zlabinger G, Pickl WF, Stockl J, Knapp W
Molecular characterization of human 4Ig-B7-H3, a member of the B7 family with four Ig-like domains.
J Immunol. 2004 Feb 15;172(4):2352-9. doi: 10.4049/jimmunol.172.4.2352.
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- 14764704 [ View in PubMed]
- Abstract
In an effort to characterize molecules with immunoregulatory potential, we raised mAbs to human dendritic cells. We selected an Ab that recognizes a molecule that is induced on monocytes differentiated in vitro toward dendritic cells. Retroviral expression cloning identified this molecule as B7-H3, a member of the B7 family described recently. In contrast to an earlier report, in which B7-H3 was described as a molecule consisting of two Ig-like domains, our cDNA encoded a type I membrane protein with four Ig-like domains, and the molecule identified by us was therefore named 4Ig-B7-H3. mRNA analysis as well as Western blotting experiments performed by us did not reveal evidence for a small B7-H3. B7-H3 is not expressed on peripheral blood lymphocytes, monocytes, or granulocytes. Upon in vitro stimulation, the expression of B7-H3 is induced on T cells, B cells, and NK cells. A number of different approaches were used to investigate the function of human B7-H3. In contrast to an earlier report, our data do not support a costimulatory role of B7-H3 in anti-CD3-mediated activation of the TCR-complex resulting in T cell proliferation and IFN-gamma production.