PMID: 2478540Oct 25, 1989Paper

Synthesis and expression of C1 inhibitor by human umbilical vein endothelial cells.

The Journal of Biological Chemistry
A H SchmaierD B Cines

Abstract

The biologic activity of C1 esterase, activated forms of factor XII and kallikrein at sites of vascular inflammation may be regulated by C1 inhibitor (C1 INH) elaborated by endothelial cells. Therefore, we investigated whether human umbilical vein endothelial cells (HUVEC) in culture produce C1 INH. Passaged HUVEC contain 1.6 +/- 0.8 micrograms of C1 INH/10(8) cells (mean +/- S.D.; n = 7) which was immunochemically similar to plasma C1 INH measured by a competitive enzyme-linked immunosorbent assay. Methylamine-treated lysates of HUVEC contained a functional inhibitor of purified kallikrein (2.7 +/- 0.8 micrograms activity/10(8) cells, mean +/- S.D.; n = 4). The HUVEC-derived kallikrein inhibitory activity was mostly C1 INH because it was reversed by chemically treating the lysate with chloroform and was neutralized by anti-C1 INH antibody. A lysate of HUVEC derived from an umbilical cord from a patient with Type I hereditary angioedema contained less than 30% of the normal levels of C1 INH antigen and activity. Immunohistochemical staining of HUVEC demonstrated a diffuse pattern of staining for C1 INH. HUVEC C1 INH was also expressed on the endothelial cell surface as detected by binding of anti-C1 INH antibody to intact monol...Continue Reading

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