Mannose ligand receptor assay as a test to predict fertilization in vitro: a prospective study.

OBJECTIVE: To assess whether mannose receptor assays can predict fertilization outcome in vitro. DESIGN: A prospective, double-blind study of the mannose receptor properties of spermatozoa. SETTING: Assisted human reproduction program at a university hospital. PATIENT(S): Partners of 140 consecutive women undergoing their first in vitro fertilization cycle. INTERVENTION(S): Motile sperm populations were tested for surface receptors for mannose by measuring their ability to bind fluorescein-labeled mannosylated albumin and to undergo a free mannose-induced acrosome reaction as judged by Pisum, sativum agglutinin binding. MAIN OUTCOME MEASURE(S): Mannose receptor assay results were correlated with fertilization outcomes using several statistical tests, including the chi2 test, chi2 for proportions, t-tests, analysis of variance with Student-Newman-Keuls tests and correlational and receiver operating characteristic (ROC) curve analysis. RESULT(S): The fractional increment increase on incubation in the percent of sperm binding mannose ligand over an intact acrosome correlated with fertilization rates in vitro. Threshold values of mannose ligand binding and of mannose-induced acrosome reactions predictive of fertilization rates were identified by ROC curve analysis. Men were thus classified into one of four groups with differing fertilization rates in vitro. CONCLUSION(S): The increment increase in sperm surface mannose ligand binding by acrosome-intact sperm correctly predicts high and low fertilization rates in vitro and identifies cases where conventional insemination can result in failed fertilization.

Acrobeads test as a predictor of fertilization in vitro.

PROBLEM: To determine whether the results of the Acrobeads test, which measures the expression of the complement regulator molecule CD46 on the inner acrosomal membrane following the acrosome reaction, accurately identifies semen specimens that will exhibit reduced or failed fertilization following conventional IVF insemination. METHOD: The Acrobeads test was performed on semen specimens from 97 consecutive patients preparing to undergo an IVF cycle utilizing a standardized insemination protocol. Motile sperm populations were examined at 6 h and 24 h post-isolation for sperm-bead agglutination. Results of the Acrobeads test were compared to that of TRITC-PSA staining in matched specimens to directly measure the spontaneous loss of acrosome content. The percentages of TRITC-PSA-negative sperm were determined in freshly isolated motile populations and in duplicate aliquots incubated 18 to 20 h under sperm capacitating conditions. The relationship between the results of both analyses estimating spontaneous acrosome reactions and the rate of fertilization of metaphase II oocytes was examined. RESULTS: The Acrobeads score did not correlate significantly with the rate of fertilization by insemination at 6 h or at 24 h. The negative predictive value of this test was 21.4%. There was no correlation between the Acrobeads score and the percentage of sperm undergoing a spontaneous acrosome reaction as detected by TRITC-PSA labeling. In contrast, the increment increase in the percentage of spontaneous acrosome reactions as quantified by TRITC-PSA staining was correlated with the fertilization rate. CONCLUSIONS: Contrary to previous reports, our prospective, double-blinded study failed to demonstrate that the Acrobeads test can accurately predict fertilization outcome in IVF. Therefore, the routine use of this test to screen patients prior to an IVF cycle in order to select appropriate treatment (i.e., ICSI) cannot be recommended.