Peanut allergy

Wibbs

Did anyone else see this?

http://news.bbc.co.uk/2/hi/americas/4481546.stm Very tragic.

A further link http://news.bbc.co.uk/2/hi/health/4022329.stm notes a study that found
"...large amounts of peanut proteins travel quickly through the gut to the immune system and trigger an allergic response."

How is this handled in non allergenic people, or is this normal and other proteins from other foods do the same? Pardon my ignorance if this is an obvious question. You would think that eating meat would be a more likely source of allergic reactions. I know fish(and animal dander) can be an issue with some, but it seems that plant proteins are more problematic(gluten and even the proteins in pollen).

The bit about the one in fifty kids with similar problems is a scary statistic.

DrIndy

Allergies and their responses are a complex set of syndromes. To be clear and allergy is a serious reaction such as an itchy raised rash called urticaria or angioedema (face and neck swelling) or full anaphylaxis where there is massive release of histamine (an inflammatory compound that causes blood vessel pores to open) that results in blood pressure crashing and massive swelling and death.

What happens is the immune system is for some reason oversensitive to this or simply sensitive to it. It is an IgE (immune antibody that targets the antigen) mediated reaction, rather than IgG or IgM reaction normal in viral or bacterial infections. IgE and eosinophils are normally used to attack large objects that cannot be enveloped and digested such as parasites like intestinal worms (indeed there is a link between low levels of parasites in developed countries and high rates of allergies/atopy).

When they are triggered, its a strong reaction, but should be localised to the object in question to best destroy it (such as a worm in the gut), however if you get a false antigen like peanuts, it is distributed across the whole blood stream and thus ALL eosinophils are activated and ALL histamine is released causing the sudden and deadly reaction.

The area concerning allergies and eosinophils is poorly understood as an immune mechanism currently.

Interestingly to what I eluded to is that atopy/allergy is common in western civilizations where there are few parasite. Atopy symptoms are things like asthma and hayfever. Although giving someone with asthma intestinal worms would probably cure the asthma, there are ethical considerations for doctors before going down this route.

DrIndy

It is possible to be allergic to literally anything, including all medicines (although penicillin is most common) as well as any food (nuts being common), any animal (venom is common) or anything at all such as certain dusts or chemicals.

All are IgE mediated and for some reason the eosinophils which target these groups are activated as they believe it is a parasitic invasion. The immune cells multiply to stand on guard to defend from the next invasion and on that occuring react very violently.

Treatment of anaphylaxis however is quite simple unlike the cause. Immediately giving adrenaline causes blood vessel constriction which increases blood pressure, giving antihistamines blocks further release of histamine and steroids are given to dampen the immune system. All this is done at the same time of supporting the circulation such as giving large amounts of fluids and perhaps putting in an airway to ensure they can breathe.

It is also possible for women (who are most unfortunate!!!) to be allergic to semen.