HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gigli, I. Articles by Austen, K. F. Search for Related Content PubMed Articles by Gigli, I. Articles by Austen, K. F.

The Stoichiometric Measurement of the Serum Inhibitor of the First Component of Complement by the Inhibition of Immune Hemolysis¹

From the Department of Medicine, Harvard Medical School at the Robert B. Brigham and Peter Bent Brigham Hospitals, Boston, Massachusetts

Abstract

A sensitive technique for the measurement of the activity of the -2-globulin inhibitor of the activated first component of complement has been described. The reaction is based on the ability of this inhibitor to block C'1a in a stoichiometric fashion in immune hemolysis.

A hemolytic unit of C'1aINH has been defined as the amount required to inhibit 63% of one effective molecule of C'1a in the presence of a total dose of from 1.5 to 2.5 effective molecules per cell. The C'1a inhibitor is stoichiometrically depleted by its interaction with fluid phase hemolytically active C'1a. C'1aINH is equally effective in blocking C'1a in the fluid phase or on the cell.

C'1aINH activity can be measured in human serum after removal of C'1 by precipitating the latter at low ionic strength, pH 7.5. Normal levels for C'1aINH activity are 37,445 ± 17,790 units/ml. Patients with hereditary angioedema were found to have a 99% reduction in C'1aINH activity.

Footnotes

Supported by Grant AI-07722 from the National Institute of Allergy and Infectious Diseases, Grant AM-05577 from the National Institute of Arthritis and Metabolic Diseases, and a grant from the Milton Fund.

² Visiting Investigator, Howard Hughes Medical Institute.

³ Postdoctoral Research Fellow of the Medical Foundation, Inc.

This article has been cited by other articles:

				K Whaley and S Ruddy Modulation of C3b hemolytic activity by a plasma protein distinct from C3b inactivator Science, September 10, 1976; 193(4257): 1011 - 1013. [Abstract] [PDF]

				G. A. McMahon, E. Petitclerc, S. Stefansson, E. Smith, M. K. K. Wong, R. J. Westrick, D. Ginsburg, P. C. Brooks, and D. A. Lawrence Plasminogen Activator Inhibitor-1 Regulates Tumor Growth and Angiogenesis J. Biol. Chem., August 31, 2001; 276(36): 33964 - 33968. [Abstract] [Full Text] [PDF]