A method for the accurate measurement of opsonic activity in uterine secretions of the mare.

This study was undertaken to develop a method for accurately measuring opsonic activity in the uterine secretions of the mare. Ten mares were used in the study. They ranged in ages from 6 to 19 years and were of various genital health status. Undiluted uterine secretions were collected by inserting a tampon into the uterus during estrus; serum samples were collected simultaneously Opsonic activity in the secretions and serum was analyzed in a chemiluminescence assay, in which zymosan particles were opsonized. Opsonic activity was determined as peak chemiluminescence, time to peak chemiluminescence, and total chemiluminescence (area under curve). The peak chemiluminescence was 16 to 17 times higher when uterine secretions were used for opsonization rather than when buffer was used. Compared to the opsonic activity in serum, the peak chemiluminescence was 21% (P</=0.05) lower, the time to peak chemiluminescence was 117% (P</=0.05) longer, and the total chemiluminescence over 60 minutes was 7% (P</=0.05) greater in the uterine secretions. These data show that opsonic activity in the uterus is approximately of the same magnitude as that in the circulation.