The development of an ELISA for the quantification of antibodies against CD52G, a sperm coating glycoprotein, in the sera of patients with infertility
Marcus, Claire E.
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Antisperm antibodies (ASA) are thought to be a predominate cause of immune infertility by interfering with various aspects of sperm function in both the male and the female reproductive tracts. The precise mechanism by which these antibodies contribute to infertility, as well as their etiology, remains to be established. ASA are present in a variety of biological substrates, such as genital tract secretions, and the blood sera of both males and females. Although not all ASA underly infertility, a substantial body of research suggests that certain ASA, referred to as sperm immobilizing antibodies (SI-Abs) and sperm agglutinating antibodies, significantly impair sperm transportation in the female reproductive tract. High titers of sperm agglutinating or sperm immobilizing antibodies have been associated with reproductive failure. CD52g is a GPI anchored glycoprotein found on mature sperm and in seminal plasma (SP). Antibodies against a male reproductive tract-specific epitope of CD52g are known to readily agglutinate sperm. The current study sought to develop an ELISA to quantify the prevalence of CD52g antibodies in the sera of male and female patients with infertility, and to determine if there was a correlation between the prevalence of CD52g antibodies and the prevalence of sperm agglutinating antibodies in the sera of these patients. Ultimately, CD52g antibodies were only detected in the sera of patients (21%) with sperm agglutinating antibodies. While detecting CD52g antibodies in sera via an ELISA proved challenging, the results of this study corroborate research demonstrating that CD52g antibodies have a remarkable capacity to agglutinate sperm. Elucidation of the mechanisms underlying this immune response would advance our understanding of immune modulation in human reproductive tracts, further the diagnosis of immune infertility, and are currently providing the basis for the development of a potent dual purpose immunocontraceptive, that both prevents unintended pregnancy, and prevents the transmission of sexually transmitted infections (STIs).