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 Google Scholar Google Scholar Articles by Linscott, W. D. Search for Related Content PubMed Articles by Linscott, W. D.

Complement: Effects of C1 Binding Affinity on the Efficiency of the C2 Reaction¹

From the Department of Microbiology, University of California at San Francisco, San Francisco, California 94122

Abstract

A variable amount of the C1 will dissociate from IgG-sensitized EAC14 at 30°C, µ = 0.065, depending on the relative amounts of antibody and C1 employed. for this reason, use of 30°C and µ = 0.065 for reacting C2 with IgG-sensitized EAC14 is inefficient, particularly with low IgG concentrations. Decreasing the ionic strength to 0.032 prevents dissociation of weakly-bound C1 during the C2 reaction at 30°C, and thus gives optimal results. Similar but not quite as good results can be obtained by adding 100 to 200 molecules of IgM anti-Forssman antibody/cell. It is suggested that this added IgM may function by capturing C1 which dissociates from IgG-SAC14 at 30°C, µ = 0.065. The resulting IgM-SAC1 could activate C2 molecules which then could bind to the IgG-SAC4, converting them to IgG-SAC42 which in turn could react with C3 and later components.

Excessive amounts of IgM (1000 to 10,000 molecules/cell under the conditions employed here) can reduce the efficiency of the reaction with C2, perhaps by raising the C1 binding affinity above some optimal level and/or by taking control of some of the C4 sites away from the more efficient IgG antibody molecules. Given a relatively constant number of molecules of C1/cell, IgM-sensitized EAC14 show a progressive decrease in C2 reaction efficiency with increasing amounts of IgM/cell over a 100-fold range of SA/SAC1 ratios.

Footnotes

¹ This work was supported by the American Cancer Society E 529.