Question 1: Why does the immune system not act on sperm cells as sperm cells are developed after puberty?

Question 2: Does immune response occur when a person's own cells are injected inside their bodies?

  • $\begingroup$ Q1: Immune system recognizes gametes as self. Q2: Do you mean filling a syringe with ejaculate and injecting it back into the donor? That would be weird and likely unadvisable, mainly because the proteins, carbohydrates, and lipids found in ejaculate would likely cause an inflammatory response as they are accessing areas, (subcutaneous or intramuscular) that are generally sterile. Also ejaculate can carry bacteria and viruses that could also cause an infection. $\endgroup$
    – AMR
    Sep 14, 2015 at 10:42
  • $\begingroup$ @AMR OP is not asking for an advise but presenting a hypothetical situation. $\endgroup$
    Sep 14, 2015 at 11:13
  • $\begingroup$ @WYSIWYG Your edit for question two is over specific. Original: "Question 2: when own cells are injected to same person then strong immune system occurs?" That in no way implies an intravenous injection. That would be an even worse idea as it would likely cause an embolism that would kill you before the immune system had a chance to figure out what was happening. $\endgroup$
    – AMR
    Sep 15, 2015 at 0:35
  • $\begingroup$ @WYSIWYG And my comment was not intended for advice. It was to say that it is a bad question to ask. and even if you were looking at it from an actual experimental design perspective, it would be almost impossible to get the permission of an ethics review panel to conduct the experiment. If is also bad in the sense that you could not ascertain what the antigen was even if you did go ahead with the experiment. You would need to isolate individual plasma membrane proteins, lipids and carbohydrates and test each separately to determine what if any antigen was producing an immune response. $\endgroup$
    – AMR
    Sep 15, 2015 at 0:41
  • $\begingroup$ @WYSIWYG As there is likely no modern literature published to elucidate question 2, and there would likely not be any ethically acceptable experiments that could determine the outcome. That question should be deleted. Question 1 is simply that the testes are immune privileged parts of the body. While the Wikipedia article speculates that they are immunogenic due to delayed development, the more likely reason is that sperm puts up fewer HLA surface proteins than somatic cells, which would make them a target for NK-cells, as NK's perform quorum sensing to determine whether to kill. $\endgroup$
    – AMR
    Sep 15, 2015 at 0:52

1 Answer 1


Body does not act against sperms because the testes are isolated immunologically by the blood testis barrier.

In mumps due to this barrier becoming ineffective due to inflammation, orchiditis (inflammation of testis) may occur and this may render the person infertile in some cases.

Such antigens which are not exposed to body's immune system are called cryptic antigens.

One more example of cryptic antigen is the antigens of the cornea.

For more information see here.

For more you can search for blood testis barrier.

For the second question, immune reaction will occur if the injected cell contains cryptic antigens. If there are no cryptic antigens then there will be no reaction.

For cryptic antigens see here.


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