The effect of freezing on sperm-associated immunoglobulin G (IgG)

Previously frozen and fresh sperm from infertile and fertile men were assayed for sperm-associated immunoglobulin G (IgG) to determine the effect of a simple freezing technique on the assay results. A direct radiolabeled antiglobulin assay (DRAA) and a direct fluorescein-labeled antiglobulin assay (DFAA) utilizing a fluorescein-activated flow cytometer were employed. The amount of IgG detected by the DRAA and the percentage of sperm that fluoresced in the DFAA generally declined when frozen sperm were used, but only the DFAA showed a statistically significant decrease. However, the degree of decline was predictable (r = 0.91 in both assays), and whether the test remained positive or negative when frozen sperm were used was not significantly affected.