Sperm agglutination is the adherence of motile spermatozoa to each other (see Fig. 1). The formation of conglomerates (compounds) of cells impairs their ability to progressive movement, which may cause a decrease in fertility. When sperm agglutination is detected, additional tests are performed to detect antisperm antibodies.
Fig. 1 - Sperm agglutination in the study of ejaculate.
It is important not to confuse with each other such concepts as sperm aggregation and sperm agglutination. During aggregation, sperm cells are glued to epithelial cells, destroyed cells or mucus, or immobile spermatozoa are glued together. During agglutination, only motile spermatozoa stick together. They can stick together head to head, flagellum to flagellum or in a mixed version (see. Fig. 2).
Fig. 2 - Different variants of sperm agglutination.
The degree of sperm agglutination
There are 4 degrees of sperm agglutination:
- Isolated One agglutinate (the mass of glued cells) contains less than 10 spermatozoa, most of the cells are free.
- Medium degree. In one agglutinate of 10-50 cells, there are free spermatozoa.
- Significant degree. In the agglutinate more than 50 cells, single spermatozoa are free.
- Heavy degree. Agglutinates are interconnected, there are no free sperm.
Agglutination does not necessarily indicate an immunological cause of infertility , but in order to confirm or exclude this cause, additional studies are being conducted to identify antisperm antibodies. Antisperm antibodies can be found on the sperm cells themselves or in the biological fluids of a man.
Detects antibodies on sperm.
MAR test or mixed antiglobulin test
Inexpensive, simple to perform, sensitive, but less informative than a direct test with immune balls (see below).
A sample of the ejaculate is mixed with either latex beads coated with antisperm immunoglobulins (antibodies) or with similarly treated human erythrocytes. Next, anti-immunoglobulin is added to the suspension. In the presence of antisperm immunoglobulins on spermatozoa, anti-immunoglobulin sticks together (agglutinates) spermatozoa with balls. The appearance of such mixed conglomerates will indicate the presence of antibodies on the sperm. Uncoated cells will float freely between agglutinates.
Immune Ball Direct Test
The particles coated with rabbit anti-human immunoglobulins against antisperm antibodies are mixed with washed sperm. If these particles begin to bind to motile spermatozoa, then anti-sperm antibodies are present on the surface of the cells.
Conducted to detect antisperm antibodies in biological fluids: seminal plasma, serum. They are used in cases where there are not enough sperm (oligozoospermia) in the ejaculate under study, or too few motile spermatozoa (asthenozoospermia). At the same time, washed donor spermatozoa, which obviously do not have antisperm antibodies, are added to the diluted biological fluid. If these antibodies are in the test liquid, they will contact the donor spermatozoa, after which a direct reaction can be carried out.
The threshold value is considered to be 50% of motile spermatozoa coated with antibodies. When it is exceeded, problems with fertilization can occur both in natural conditions and during IVF.
Reduced male fertility due to immune factors can be determined by several reasons.
Violation of the blood-test barrier
Since spermatozoa begin to form after puberty — that is, when the immune system has been functioning for a long time — their proteins are perceived by the immune system as foreign. The hematotestericular barrier separates the blood cells from the reproductive system cells, preventing the immune cells from entering the spermatic cord. When it is damaged, the immune cells “read” information about sperm proteins and the body begins to produce antisperm antibodies (immunoglobulins). Damage to the blood-test barrier is possible with:
- scrotal injuries;
- after suffering orchitis (inflammation of testicular tissue);
- some infections (chlamydia);
- overheating of the scrotum ( varicocele , cryptorchidism);
- chronic ischemia ( with inguinal hernia ).
Cross-reactions with antigens of microorganisms
The antigens of some infectious agents, for example Staphylococcus aureus, Escherichia coli, Pusillus bacillus and Proteus, have molecular similarities with some surface sperm proteins. This can “mislead” the immune system. Other microorganisms, such as chlamydia, can attach to the surface of the sperm cell, triggering immune responses. In addition to the presence of the pathogen, the characteristics of the organism also matter - the propensity for an excessive response of the immune system.
Sperm agglutination and the identification of antisperm antibodies indicate the immune causes of reduced male fertility. The causes of this condition may be different, and a thorough andrological examination is necessary to identify them. Only after that it will be possible to understand whether autoimmune infertility is reversible, or whether it is necessary to resort to assisted reproductive technologies.
Sometimes for successful fertilization, intrauterine injection of sperm is sufficient, in other cases, more complex methods, such as ICSI, may be required. In any case, the attending physician should suggest the tactics of further actions after the identification of sperm cell agglutination.