Update in Reproductive Immunology

Update in Reproductive Immunology
Reproductive immunology refers to a field of medicine that studies interactions (or the absence of them) between the immune system and components related to the reproductive system, such as maternal immune tolerance towards the fetus, or immunological interactions across the blood-testis barrier. The concept has been used by fertility clinics to explain the fertility problems, recurrent miscarriages and pregnancy complications observed when this state of immunological tolerance is not successfully achieved. Immunological therapy is the new up and coming method for treating many cases of previously “unexplained infertility” or recurrent miscarriage.

Between mother and fetus

  • The fact that the embryo’s tissue is half foreign and unlike mismatched organ transplant, it is not normally rejected, suggests that the immunological system of the mother plays an important role in pregnancy. The placenta also plays an important part in protecting the embryo for the immune attack from the mother’s system. Studies also propose that proteins in semen may help woman’s immune system prepare for conception and pregnancy. For example, there is substantial evidence for exposure to partner’s semen as prevention for pre-eclampsia, largely due to the absorption of several immune modulating factors present in seminal fluid, such as transforming growth factor beta (TGFβ).

Sperm cells within a male

  • The presence of anti-sperm antibodies in infertile men was first reported in 1954 by Rumke and Wilson. It has been noticed that the number of cases of sperm autoimmunity is higher in the infertile population leading to the idea that autoimmunity could be a cause of infertility.Anti sperm antigen has been described as three immunoglobulin isotopes (IgG, IgA, IgM) each of which targets different part of the spermatozoa. If more than 10% of the sperm are bound to anti-sperm antibodies (ASA), then infertility is suspected. The blood-testis barrier separates the immune system and the developing spermatozoa. The tight junction between the Sertoli cells form the blood-testis barrier but it is usually breached by physiological leakage. Not all sperms are protected by the barrier because spermatogonia and early spermatocytes are located below the junction. They are protected by other means like immunologic tolerance and immunomodulation.
  • Infertility after anti-sperm antibody binding can be caused by autoagglutination, sperm cytotoxicity, blockage of sperm-ovum interaction, and inadequate motility. Each presents itself depending on the binding site of ASA.

Immunocontraceptive vaccine

  • Experiments are undergoing to test the effectiveness of an immunocontraceptive vaccine that inhibits the fusing of spermatozoa to the zona pellucida. This vaccine is currently being tested in animals and hopefully will be an effective contraceptive for humans. Normally, spermatozoa fuse with the zona pellucida surrounding the mature oocyte; the resulting acrosome reaction breaks down the egg’s tough coating so that the sperm can fertilize the oovum. The mechanism of the vaccine is injection with cloned ZP cDNA, therefore this vaccine is a DNA based vaccine. This results in the production of antibodies against the ZP, which stop the sperm from binding to the zona pellucida and ultimately from fertilizing the oovum.
  • Another vaccine in investigation is one against HCG. This immunization would produce antibodies against hCG and TT. Antibodies against hCG would prevent the maintenance of the uterus for a viable pregnancy therefore preventing contraception. Another vaccine that is utilized is the peptide β-hCG that is more specific to hCG and a more rapid and effective response occurs in the absence of LH, FSH, and TSH.
  • This area of the immunology is devoted to the study of immunological aspects of the reproductive process including fetus acceptance. The term has also been used by fertility clinics to address fertility problems, recurrent miscarriages, premature deliveries and dangerous complications such as pre-eclampsia.

Immunology

  • Immunology is a branch of biology that covers the study of immune systems in all organisms. It was the Russian biologist Ilya Ilyich Mechnikov who boosted studies on immunology, and received the Nobel Prize in 1908 for his work. He jabbed the thorn of a rose on a starfish and noted that, 24 hours later, cells were surrounding the tip. It was an active response of the body, trying to maintain its integrity. It was Mechnikov who first observed the phenomenon of phagocytosis, in which the body defends itself against a foreign body, and coined the term. Immunology charts, measures, and contextualizes the: physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders (such as autoimmune diseases, hypersensitivities, immune deficiency, and transplant rejection); the physical, chemical and physiological characteristics of the components of the immune system in vitro, in situ, and in vivo. Immunology has applications in numerous disciplines of medicine, particularly in the fields of organ transplantation, oncology, virology, bacteriology, parasitology, psychiatry, and dermatology.
  • Prior to the designation of immunity from the etymological root immunis, which is Latin for “exempt”; early physicians characterized organs that would later be proven as essential components of the immune system. The important lymphoid organs of the immune system are the thymus and bone marrow, and chief lymphatic tissues such as spleen, tonsils, lymph vessels, lymph nodes, adenoids, and liver. When health conditions worsen to emergency status, portions of immune system organs including the thymus, spleen, bone marrow, lymph nodes and other lymphatic tissues can be surgically excised for examination while patients are still alive.
  • Many components of the immune system are typically cellular in nature and not associated with any specific organ; but rather are embedded or circulating in various tissues located throughout the body

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