THE INDIRECT IMMUNOBEAD TEST FOR SEMINAL ANTISPERM ANTIBODIES AND FERTILIZATION RATES AT IN-VITRO FERTILIZATION

A series of 183 patients with positive indirect immunobead tests on se men was studied to determine the correlation in semen between specific antibody types, binding sites, antibody concentration, and fertilizin g ability. IgM was present in only 44 ejaculates and was present in su fficient quantity to cause significant binding to immunobeads (i.e. >2 0% of motile donor spermatozoa) in only three of them, There was no co rrelation between the percentages of motile donor spermatozoa that bou nd IgA and IgG immunobeads but the two classes of beads generally houn d to the same region of the spermatozoa, A total of 63 couples went on to attempt in-vitro fertilization (IVF) treatment, all with mature eg gs recovered, Of these mature eggs, 44% were fertilized and cleaved no rmally in comparison to 68% in a group of patients with tubal disease, Fertilization rates in individuals followed a bimodal distribution wi th a substantial number of couples experiencing zero or very poor rate s (0-20%), the mode for the remainder lying between 60 and 80%. The fe rtilization rate tended to decrease as the amount of antibody increase d. The percentage of donor spermatozoa that bound to immunobeads, take n as the greater of IgA and IgG, was selected by logistic regression a s a significant predictor of poor fertilization (rate less than or equ al to 25%). The predictive power of the equation was improved by inclu ding the motile normal sperm concentration but the equation could only account for a small proportion of the total variation in fertilizatio n rate, The presence of antibodies to the sperm head was highly correl ated with the antibody concentration but was not selected as a predict or of fertilization, We conclude that the nature of the antigen agains t which the seminal antisperm antibody is directed may be as important as the antibody concentration in affecting sperm function, There seem s to be little practical value in measuring IgM in seminal plasma.