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When you inject immunoglobulins as a treatment for certain diseases, the immunoglobulins are a foreign substance.

I can appreciate that maybe the constant region would be similar to the hosts as it is from another human and these don't change a lot.

However, in the variable regions, wouldn't there be the possibility that the antigen receptor region could be the complement to the patient's own antibodies? Wouldn't this trigger an immune response and destroy the injected Ig's? Yet we seem to do this procedure, so why doesn't this process occur?

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If a head-to-head "match" between antibodies from two different people was to occur, a similar match would most likely have occurred already in the donor. People have the same tissues after all.

But in the donor; the B lymphocytes producing the antibodies had to go through the processes of "central tolerance" and "peripheral tolerance".

This would weed out the cells producing autoantibodies.

Theoretically, nasty autoantibodies in the recipient could react with innocent antibodies in the donor though.

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Intravenous immunoglobulins (IVIG) are human blood products purified from the plasma from many healthy donors. These are natural proteins that your body normally makes to help you to fight infections and to serve other functions for the immune system. In addition, all immunoglobulins are screened to eliminate the possibility of carrying pathogens or other diseases 1. Since the body's immune response is activated by the recognition of T cells to the antigen, these naturally produced, screened IVIG will not trigger an immune response against them.

However, IVIG are not 100% safe. Injection of immunoglobulins can cause some adverse effects, such as fever, headache, chills, etc. These adverse effects are usually transient and mild, but there are few cases of severe side effects. You can find more details in this paper.

Resources

  1. https://www.rheumaderm-society.org/ivig/

  2. Guo Y, Tian X, Wang X, Xiao Z. Adverse Effects of Immunoglobulin Therapy. Front Immunol. 2018;9:1299. Published 2018 Jun 8. doi:10.3389/fimmu.2018.01299

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  • $\begingroup$ Re: "these naturally produced, screened IVIG will not trigger an immune response against them." In rare cases, they may indeed do so. Screening has no effect on this, rather it would be sequence differences in the Ab genes between the donor and recipient. In practice, such sequence differences are minimal enough between humans that no effect is normally observed. For animal Abs injected into humans, a reaction is more likely, so such Abs are often first engineered (before or after antigen selection) to replace much of the molecule with human sequences (see "chimeric" or "humanized" Abs) $\endgroup$
    – Armand
    Jun 4, 2021 at 8:13
  • $\begingroup$ Screening of IVIG is very good, but not perfect, in identifying pathogens, and so there is a quite small risk of infection for the recipient. $\endgroup$
    – Armand
    Jun 4, 2021 at 8:17

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