These can be produced in the man or the woman (but more usually the man). If produced in the man they can cause the sperm to stick together (agglutinate) or reduce sperm movement and can prevent the sperm fertilising the egg. In a man the most probable cause of antibodies is a previous injury to the testicles.
The reason why some women produce antibodies to sperm is not properly understood. They do, however, sometimes produce them and they can be found in the cervical mucus. They may attach themselves to the sperm making it hard for them to move and making them a target for white blood cells to attack.
The treatment for anti-sperm antibodies depends on the level of the antibodies that are present as lower levels may have no noticeable affect on fertility. If, however, a high concentration of antibodies is present then the treatment of choice is intra-cytoplasmic sperm injection (ICSI).