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 Bernard, A. Articles by Day, N. K. Search for Related Content PubMed Articles by Bernard, A. Articles by Day, N. K.

Leukocyte-Derived Complement Inhibitor

IV. The Functional Properties of C Bound to Erythrocytes Pretreated with Leukocyte Culture Supernatant¹

Sloan-Kettering Institute For Cancer Research, New York, New York

Abstract

E, pretreated with leukocyte cultures supernatant (ES), binds C through C1q; ES and EIgM that bind the same amount of C as measured in a hemolytic assay have the same uptake of ¹²⁵I-C1q; ESC1q and EIgMC1q, carrying the same number of molecules of C1q per cell, have the same uptake of C1r and C1s; soluble immune complexes prevent the binding of C and C1q to ES. The activity of C bound to ES is impaired; ESC can react with C4 but not with C2. The C4 turnover and the C INH turnover by ESC are reduced so that ES-bound C is protected from destruction by C INH. These modifications are fully reversed when C is transferred from ES to EA: C recovers its ability to react with C2, and to react fully with C4 and C INH. Thus the C1s activity can be modulated inside the C molecular complex upon binding of C1q to a lymphocyte product. In addition, the ¹²⁵I-C1q uptake is proportional to the amount of IgM hemolysin used to sensitize E; it has, however, an exponential relationship to the amount of IgG or S used to sensitize E. The ratio of ¹²⁵I-C1q uptake to whole C uptake measured in a hemolytic assay is lower than 2. This indicates that one molecule of IgM is sufficient to bind one molecule of C1q on E, that several molecules of IgG or S are required to bind one molecule of C1q, and that one molecule of C1q is sufficient to create a lytic site on E.

Footnotes

¹ This work was presented in part at the meetings of the Federation of American Societies for Experimental Biology, Anaheim, California, 1976. It was supported by Public Health Service Research Grants CA-18488-01A1 from the National Institutes of Health, CA-17404 from the National Cancer Institute, and American Heart Association Grant AHA-75-912.

² Address reprint requests to Dr. Bernard at: Laboratoire des Tumeurs Solides de l'Enfant, Institut Gustave Roussy, 94 Villejuif, France. Dr. Bernard's work was supported in part by Delegation Generale a la Rercherche Scientifique et Technique, France.

³ Dr. Teshima is a Fellow of the Cancer Research Institute, New York.

⁴ Dr. Day is an Established Investigator of the American Heart Association.