Date of Award

1986

Embargo Period

8-1-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Microbiology and Immunology

College

College of Graduate Studies

First Advisor

Robert J. Boackle

Second Advisor

An-Chuan Wang

Third Advisor

Philippe Arnaud

Fourth Advisor

J. M. Kilpatrick

Fifth Advisor

Mariano F. LaVia

Sixth Advisor

Jack Marchalonis

Abstract

In order to clarify the mechanism of interaction of serum amyloid P component (SAP) with complement, the interaction of SAP with Clq was studied. It is known that SAP binds Sepharose 4B in the presence of calcium. 125I-Clq was retained on the Sepharose when purified 125I-Clq was incubated with SAP prior to affinity chromatography on Sepharose. In the absence of SAP, the 125I-Clq was not retained. To further examine the interaction of SAP with Clq, SAP was incubated at varying ratios with Clq. These mixtures were examined via crossed immunoelectro-immunoelectrophoresis against goat anti-SAP. A change in the electrophoretic behavior of SAP was observed in the presence of Clq. It was found that SAP interacted with the collagen-like stem of Clq. In these studies, 125I-SAP was incubated with pepsin digests of Clq in a microtitre solid-phase binding assay. In addition, a microtitre solid-phase binding assay was utilized in order to investigate the possible binding of SAP with IgG. Interestingly, human IgG and Fab2, but not Fc2, were found to bind 125I-SAP. Furthermore, 125I-SAP-IgG complexes bound to immobilized Clq, whereas 125I-SAP-Clq complexes demonstrated significantly less binding to IgG. The ability of SAP to activate complement as detected by C3 conversion was studied. It was found that SAP activated complement to a limited extent in normal human serum but caused extensive C3 conversion when serum from an individual with decreased levels of Cl inhibitor was used. Furthermore, the activation of the complement pathway by SAP in the latter serum was reversed by the addition of exogenous Cl inhibitor, indicating that SAP has the ability to play a role in the regulation of complement via the classical pathway.

Rights

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