Study of antisperm antibodies bound to the sperm cell surface and their relationship to circulating ASA

Immune Infertility Should Be Positively Diagnosed Using an Accurate Method by Monitoring the Level of Anti-ACTL7a Antibody

Infertility is currently a major public health problem. Anti-sperm antibodies (ASAs) markedly reduce sperm quality, which can subsequently lead to male and/or female infertility. The accurate detection of ASAs derived from specific spermatozoa is, therefore, clinically useful. We have focused on the spermatozoa-specific expression protein ACTL7a for many years and have developed an enzyme-linked immunosorbent assay (ELISA) to detect the concentration of anti-ACTL7a antibodies in fertile sera (n = 267) and infertile sera (n = 193). Infertile sera were collected from the positive sera of tray agglutination tests (TAT), which is a routine ASA screening methodology. We found that the concentration of anti-ACTL7a antibodies was significantly higher in the infertile sera (than in the fertile sera, P < 0.0001) and much higher in the TAT ≥ 16 infertile sera. The ELISA was much better for male sera detection (AUC = 0.9899). If we set the standard at a strongly positive value (calculated by ROC curve), the positive predictive value of the antibody detection reached 100 percent, with a false positive rate of zero. The developed ELISA method for anti-ACTL7a antibody detection is therefore sensitive, accurate, and easy to perform, making it an excellent potential tool for future clinical use.

Are antisperm antibodies indeed sperm-specific?

Antisperm antibodies (ASA) are present in a high percentage of infertile patients. The development of ASA in the male depends on the sequestration of antigens on germ cells, the testis being an immune privileged region. In this study, we investigated the specificity of ASA binding to sperm antigens by exposing a number of organ preparations to ASA. In none of the organ homogenates was a significant difference between the results of the Western blot with ASA-containing fluids, neither serum nor seminal plasma, and those without ASA observed. We conclude from our results that the ASA tested in our study obviously are sperm-specific. ASA as an autoimmune are thus restricted to spermatozoa. The antigens are suitable for trials in immune therapy, they may also serve for the development of antigen-specific diagnosis and treatment in infertility. They also indicate cognate antigens of possible immune contraceptive agents.

Antisperm antibody detection: 2. Clinical, biological, and statistical correlation between methods

PROBLEM

In clinical andrology, the detection of antisperm antibodies (ASA) is regarded as one of the most important steps in the study of male infertility. This practice is generally accepted even though there is still some disagreement about the true meaning of antisperm immunity, and there remains a good deal of controversy about the test regarded as the most suitable for the detection of antibodies directed against sperm antigens. International Workshops have tried to standardize universally accepted protocols. A panel of three or four methods is generally advised to provide a correct and complete screening of patients with antisperm immunity. The aim of the present paper is to report our studies on the correlation between direct methods (IBT, MAR test) and indirect methods (gelatin agglutination test [GAT], and tray agglutination test [TAT]) and to establish whether biological models can explain the antibody test results. An attempt was also made to establish a "predictive threshold" to explain even apparently discordant direct and indirect results.

Antisperm antibody detection: 1. Methods and standard protocol

PROBLEM

Today, antisperm antibody (ASA) detection is one of the most important steps in the evaluation of male infertility. This practice is generally accepted even though there is still some disagreement about the meaning of antisperm immunity and a good deal of controversy about the test regarded as the most suitable for the detection of antibodies directed against sperm antigens. International workshops have tried to standardize universally accepted protocols. A panel of three or four methods is generally advised to provide a correct and complete screening of patients with antisperm immunity.

METHOD OF STUDY

This paper reports on the results of a serum exchange workshop for the standardization of the ASA detection in the sera carried out under the auspices of the Italian Society of Endocrinology, which was used as reference laboratory. A careful description of the most widely used methods is reported and proposed as a standard protocol also on the basis of the results of the correlation studies carried out by our group is also reported.

CONCLUSIONS

If the proposed methods and procedures will be accepted by the members of the Alps-Adria Society for Immunology of Reproduction, a Study Group for Sperm Antibody Testing, could start its activity having the goal of reaching a consensus on methodology and carrying out a European serum exchange workshop.