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This Article Full Text Full Text (PDF) All Versions of this Article: 73/6/1243    most recent biolreprod.105.042432v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Yudin, A. I. Articles by Cherr, G. N. Search for Related Content PubMed PubMed Citation Articles by Yudin, A. I. Articles by Cherr, G. N. Agricola Articles by Yudin, A. I. Articles by Cherr, G. N.

Beta-Defensin 126 on the Cell Surface Protects Sperm from Immunorecognition and Binding of Anti-Sperm Antibodies¹

Division of Reproductive Biology, Departments of Obstetrics and Gynecology,³ Urology,⁴ and Environmental Toxicology and Nutrition,⁵ Bodega Marine Laboratory, University of California, Davis, California 94923

ABSTRACT

Beta-defensin 126 (DEFB126), formerly known as epididymal secretory protein 13.2 (ESP13.2), coats the entire primate sperm surface until completion of capacitation, and it is a candidate for providing immune protection in the female reproductive tract. To further examine the potential role of DEFB126 as a means of protection from immune recognition, cynomolgus macaque sperm were exposed to a number of treatments that are known to alter sperm surface coats, including capacitation. We used a novel in vivo assay to determine immune recognition: aldehyde-fixed whole sperm injections into rabbits. Following booster injections, immunoblot analyses of whole sperm prepared in various manners was conducted. On Days 60 and 80 post-initial immunization, the antisera showed a remarkably strong reaction to a single 34–36 kDa protein, which was shown to be DEFB126. Sera from rabbits that were immunized with sperm washed more rigorously using Percoll gradients showed an increase in the number and intensity of proteins recognized on whole sperm Western blots, although DEFB126 was still the major immune response. When capacitated sperm, from which most DEFB126 had been released, were used as the immunogen, there was a dramatic increase in the immune recognition to a variety of protein bands. Sperm treated with neuraminidase to remove sialic acid on DEFB126 before fixation were shown to still possess DEFB126, but lacked the sialic acid component of the glycoprotein. These sperm were as immunogenic as capacitated sperm even though the desialylated DEFB126 still covered the entire cell surface. These sperm lost their highly negative charge (the isoelectric point of DEFB126 shifted from pI 3.0 to pI 6.4). Experiments using different sperm plasma membrane protein-specific Igs showed that recognition did not occur when DEFB126 was present, but following capacitation these Igs readily recognized the exposed sperm membrane. Our data suggest that DEFB126 protects the entire primate sperm surface from immune recognition and that the sialic acid moieties are responsible for the cloaking characteristic of this unique glycoprotein.

beta-defensin, capacitation, gamete biology, glycocalyx, immunogenic, immunology, sperm, sperm maturation

¹ Bodega Marine Laboratory Contribution # 2245.

² Correspondence: Gary N. Cherr, Bodega Marine Laboratory, University of California Davis, PO Box 247, Bodega Bay, CA 94923. FAX: 707 875 2089; gncherr{at}ucdavis.edu