Proteomic identification of sperm antigens using serum samples from individuals with and without antisperm antibodies

The aim of the study was to identify human sperm antigens reacting with polyclonal antisperm antibodies. Protein sperm extracts were subjected to electrofocusing, and next immune reactions (immunoblotting) were carried out with positive for antisperm antibodies and control (not containing antisperm antibodies) serum samples. Proteomic analysis of human sperm proteins resulted in identification of 80 sperm antigens that could be divided into three groups: antigens specific for patients with antisperm antibodies (32), antigens recognised by both infertile patients and control sera (35) and antigens detected by control serum samples only (13). Among antigens specific for infertile patients, there were 12 sperm entities known to be involved in fertilisation process. We have also characterised three protein entities identified only by sera of infertile women. Altogether, the proteomic analysis resulted in identification of 27 sperm entities not reported previously in human sperm proteome. Identified proteins are sperm antigens that could be potentially responsible for immunological infertility. The study also sheds new light on the sperm antigens in aspect of gender specificity. The investigation of human sperm proteome by the use of antisperm antibodies-containing sera of infertile individuals not only may indicate new proteins but also can draft their immunological nature.