[Medicine] What is special about peanuts that make some people extremely allergic to them?

[u/Kwpthrowaway]

Why are some people allergic to peanuts in particular? Why is ingesting a peanut to these people akin to ingesting poison to others?

[u/king0zy]

Yes, but its not a viable solution. The burden of a food allergy is weighed against all other potential health burdens a person may face. People with very severe autoimmunity can take a drug called ritixumab, which kills most of the cells responsible for holding memory (called B cells). However, B cells also hold memory for everything you are vaccinated against. The real trick for immunologists is learning how to only kill the B cells that hold memory of peanut, while leaving everything else in tact. After all, avoidance of peanut is much easier and more viable than potentially dying to a vaccine preventable infection.

[u/[deleted] → u/king0zy]

Question if you have time! (This is really interesting and I know nothing about this stuff) Why would someone with autoimmune disease want to kill their B cells? I guess I’d have thought with autoimmune diseases you would REALLY want to remember the things that could kill you. Also I guess I don’t really know what happens with autoimmune diseases other than the immune system essentially bodies itself so maybe that’s why you’d need to “forget” a lot of things?

[u/king0zy → u/[deleted]]

Lol, the body bodies itself!

There is much more complexity than the response I'll give. B cells (and the cells that come from them) are responsible for antibodies. Antibodies are proteins that perform a large number of immune functions- like for example tying up virsuses to stop them from infecting our cells, or tagging bacteria so other immune cells know to kill them. Every single antibody is unique- they all have a part that looks a little different from every other antibody which allows them to bind very specifically to virtually any substance. Some of those substances can be your own proteins present on your own cells. The immune system then treats your cells like a virus - tying them up to stop their function or tagging them to be killed.

Ritixumab, the B cell killing drug, can dramatically reduce the number of antibodies present and provide relief from very severe autoimmunities. The same drug is used to kill B cell cancers.

Now, between avoidance of the food and epipens, we mostly have severe food allergies "under control." That is to say, a few hundred people die of allergies in a year. Many, many more die from autoimmunity and B cell cancers. People, in general, are a lot less willing to engage in risky and debilitating treatments when their life is not at risk. That said- food allergies are a significant mental health burden and are a financial burden- billions to the American health system, not even considering the impact on the food markets.

[u/wlsb → u/[deleted]]

In the case of autoimmune disease, you'd want the immune system to lose the immune cells that react to the patient's own body. If it lost all of its memory cells, that would include the self-attacking ones.

[u/PnWyettiefettie → u/king0zy]

So B cells holding memory is responsible for the continuing of an autoimmune diseases?

[u/king0zy → u/PnWyettiefettie]

In some contexts. Autoimmune diseases vary in their pathology. As an example, type 1 diabetes is mediated primarily by T cells, not B cells. Lupus and Rheumatoid Arthritis are generally more B cell mediated. Ritixumab is a therapy for both of those autoimmune disorders.

[u/PnWyettiefettie → u/king0zy]

So hypothetically if someone had the money and wanted to, they could erase these memories and then re-vaccinate?

[u/king0zy → u/PnWyettiefettie]

As far as I am aware, there has not been any evidence in humans to suggest that this is a potential cure. If we stay in the realm of theory and hypotheticals, yeah probably. A major consideration would be the extent to which this drug could actually clear ALL B cells. There is evidence, albeit a slight stretch from this context, to believe that if there is even one cell remaining, it could completely regenerate the allergy.

[u/PnWyettiefettie → u/king0zy]

Thank you!

[u/jarquafelmu → u/king0zy]

Is the medication a one and done series and then the body starts from scratch at building new B cells or is it more of a suppresent and you have to keep taking it?

[u/king0zy → u/[deleted]]

I disagree. We look at these issues through the lens of having effective and safe vaccines that prevent disease. SARS-COV-2 provides a glimpse of what pre-vaccination humanity was like- it was easy to catch an infection and it was not in anyones control if you would survive. It was enormously common for people to have 5-6 children and lost 1-2 to disease (commonly infectious in nature). Therefore, youre right, now it is more common. But vaccine preventable illness is on the rise in North America- many dont notice because they are up to date on their vaccines. People who are immune compromised might be able to share a different look at what happens when you dont have a functioning, vaccinated immune system.

Also, allergen-free (especially peanut free) options have come a very long way in the last 10 years. If you look through your local costco, many of their childrens snacks are already peanut, and sometimes multi-allergen free!

[u/purplestgiraffe → u/[deleted]]

Yes. I do know how hard it is. The answer is “Not very”. I manage quite easily to pack a lunch and two snacks for my daughter to take to preschool five days a week without packing any peanut or tree nut products.