Application of the quantitative sperm immobilization test for follow-up study of sperm-immobilizing antibody in the sera of sterile women.

For quantitative estimation of sperm immobilizing antibody, a new assay method was developed and applied to a follow-up study of antibody titers in the sera of sterile women. The 50% sperm immobilization units (SI50) estimated by the quantitative method ranged from 1.2 to 97.3 in the sera from 16 sterile women who showed relatively high antibody activities in the previous semiquantitative sperm immobilization test. When the quantitative antibody titers, SI50, were followed over 3 years in sterile women with the sperm immobilizing antibody, the antibody titers were found to be unstable, and undulated over a period of several months. Therapy consisting of use of a condom seemed to be ineffective in decreasing the antibody titers.