[Comparison of the indirect immunobead test and the sperm immobilization test for detection of antisperm antibody]

The indirect immunobead test (indirect IBT; IgG.IgA) and the sperm immobilization test (SIT) were carried out for 75 infertile patients to detect antisperm antibodies in the sera. The results were as follows. 1) Twenty three cases showed positive results in the IBT, and 14 out of the 23 showed also positive in the SIT. 2) Fifty two cases which had negative results in IBT also had negative results in SIT. 3) IgG-IB attached to sperm were observed in 14 with positive SIT, but no IgA-IB were observed in 4 cases out of the 14. 4) IgG-IB attached to both the sperm head and end-tail in 12 cases out of the 14, but only to the sperm end-tail in the other 2 cases. We therefore concluded that, 1) IBT detected anti-sperm antibodies more readily than SIT. 2) IBT was an alternative to SIT for screening. 3) Sperm immobilization antibodies appeared to be in the IgG class rather than in the IgA class. 4) It appeared that sperm immobilization antibodies might be able to attach to the sperm tail as well as the head.