Identification of 2 stallion sperm-specific proteins and their autoantibody response

In this study, 2 stallions were immunised with their own spermatozoa to ascertain whether an antisperm autoantibody response could be mounted. The results demonstrated that the stallion can recognise and respond to sperm autoantigens by producing circulating antisperm antibodies, primarily of the IgG class. Such autoantibodies appeared 2-4 weeks after inoculation and persisted for 6-20 weeks. Immunochemical characterisation by western blot identified two major sperm autoantigens, with molecular weights of 70 kD and 62 kD. Control pony stallions immunised with adjuvants alone failed to exhibit such antibodies. IgA antisperm antibodies were measurable in seminal plasma of both stallions. We suggest that, as in other species, autoimmunity to spermatozoa may play a role in idiopathic subfertility in stallions.