Anti-zona pellucida antibodies in the serum and the follicular fluid of infertility patients undergoing in vitro fertilization

Using an indirect immunofluorescence assay with porcine ova, 11 of 69 (15.9%) women with infertility and 13 of 46 (28.3%) women with recurrent spontaneous abortion of undetermined etiology had anti-zona pellucida antibody titers of 1.4 or greater. In contrast, none of 56 control individuals has positive anti-zona pellucida titers. Forty-two infertility patients undergoing in vitro fertilization were fertilized for levels of circulating anti-zona pellucida antibodies. Six of 42 patients (14.3%) had circulating antibody titers of 1:4 or greater. In 16 of these patients, paired serum and follicular fluid antibody titers were compared. Of these, five had positive serum titers (1:4 or greater). Of these five, four were found to also have antibody in the follicular fluid at a titer of 1:2 or greater. Of the remaining 11 samples that were negative for serum antibody, 5 of the corresponding follicular fluids were also negative and 6 were positive at undiluted only. These results demonstrate that antibodies against the zona pellucia can pass from the serum into the follicular fluid, and suggest that there is a relationship between the presence of serum and intrafollicular autoantibodies against the zona pellucia. The success of in vitro fertilization was correlated to the presence of anti-zona pellucida antibodies. Serum titers of 1:4 or greater, which have been suggested to be associated with infertility, did not prevent successful fertilization in vitro. However, the patient with an anti-zona pellucida titer of 1:16 was also the only patient whose ovum was unfertilized by husband's or unrelated donor sperm. In conclusion, antibodies to zona pellucia are found in the serum of some infertile women and with histories of recurrent abortion. Also, antibodies against the zona pellucia are present in the follicular fluid at concentrations similar to those found in the serum. Finally, specific antibody titers may have an effect on the outcome of in vitro fertilization.