Title

Laminin antibodies in development and reproduction: Etiology, epitopes and mechanisms

Date of Completion

January 1994

Keywords

Biology, Molecular

Degree

Ph.D.

Abstract

Analyses of sera from monkeys with histories of reproductive failure found autoantibodies to laminin were the embryotoxic factor within the serum. When monkeys with excellent reproductive histories were immunized with laminin, their sera became embryotoxic and they could not reproduce successfully. Sera from some rats immunized with laminin were embryotoxic, while others were not embryotoxic. Antilaminin antibody levels in these rats could not predict toxicity, however toxic sera was found to recognize different epitopes on laminin than the nontoxic sera.^ As the monkeys in the original study had naturally occurring antibodies to laminin, the role of antilaminin autoantibodies in embryotoxicity was examined. Injection of mercuric chloride into Brown Norway rats has been found to induce autoimmune glomerulonephritis that produced autoantibodies to laminin. In the present study, sera from Brown Norway treated with mercuric chloride were tested in culture and were associated with embryotoxicity and embryolethality. Affinity purified antibodies from these rats were also found to cause embryotoxicity in a dose dependent manner.^ Using laminin immunized monkey sera, the mechanisms of antilaminin antibody embryotoxicity was found to involve the antilaminin antibodies binding to the cell surfaces of the visceral yolk sac. This binding was found to cause reductions in the number of microvilli on the cell surfaces that in turn reduced the uptake of nutrients. Methionine supplementation was found to overcome the toxicity of sera from one monkey and not the other. This was linked to the level of antibody binding to the yolk sac. As epitope specificity of antilaminin antibodies were found to distinguish toxic and non-toxic sera, monkeys were immunized with four characterized laminin peptides, YIGSR, RGD, IKVAV and a peptide of no known function. Sera from the YIGSR and RGD immunized monkeys were embryotoxic and these monkeys could not reproduce successfully. Again toxicity was related not to antilaminin antibody levels but to yolk sac binding. This suggested that toxicity of antilaminin antibodies was related to the exposure of laminin epitopes in the yolk sac. ^