Post-obstruction rat sperm autoantigens identified by two-dimensional gel electrophoresis and western blotting

Although antisperm autoantibody responses to obstruction of the male reproductive system have been documented, information on the nature of the cognate sperm autoantigens has been limited. In the present study, the patterns of sperm autoantigens recognized by sera from rats after obstruction of the vas deferens or epididymis were studied by high resolution two-dimensional (2-D) gel electrophoresis and western blotting. Comparisons of patterns of autoantigens stained on 2-D western blots of sera from prepubertal vasectomy, prepubertal epididymal ligation and adult vasectomy groups revealed both similarities and differences. Sera from sham-operated animals showed no detectable reaction or much lighter staining of a small number of spots. Visualization of sperm autoantigens on 2-D western blots supported the hypothesis that there is a relatively small set of sperm proteins that can be regarded as dominant post-obstruction sperm autoantigens because they are recognized by multiple post-obstruction sera. The 2-D analysis revealed previously undetected distinctions in the autoantigens recognized after adult and prepubertal vasectomy, as well as variations with the site of obstruction. These differences in the response may be due in part to changes in antigens of spermatozoa in different parts of the tract and at different ages, as well as variations in exposure of sperm cell proteins to the immune system resulting from the sites of spermatic granulomas. Preparative 2-D gels and western blotting with post-obstruction sera are now being used to identify specific sperm autoantigens by microsequencing of selected proteins.