First Post!

So I guess I’ve decided to name this blog “SHM”, which stands for “Somatic Hypermutation” (and not “Simple Harmonic Motion” — sorry for all the fans of The Other SHM). Here comes the stream-of-consciousness word vomit of the why: Somatic mutations aren’t passed on — they take effect locally and don’t bother anything else in the body or future generations. Somatic hypermutation, more specifically, is one of the two processes that comprise affinity maturation, which is what happens when your body is reacting to an antigen that it has seen before. It’s called affinity maturation because your body is creating a bunch of new antibodies (well, antibody-producing cells, actually) that are all slightly different but still mostly attuned to recognize the particular antigen (somatic hypermutation), and then selecting for the ones that have a higher affinity for the antigen (clonal selection). Thus, affinity maturation is part of the immunological process that allows your body to “remember” antigens, and this blog, so far as I can tell at the moment, is going to serve as a memory dumping site bank for my random thought processes that I never seem to be able to remember once they’ve concluded themselves.

It’s kind of silly, actually — I’ll have some minor epiphany at the end of a thought process, and then forget that I’d ever thought about it until someday, maybe, when I start thinking about it again. Considering how many random thought processes I have about various topics, my remembering these minor epiphanies happens less often than I might like, because they’re not accessible to me when I’m trying to randomly brainstorm things, as, for example, for writing blog posts…uh oh. I think I see a problem here…. I guess I’d better hope that my longer trains-of-thought happen when I’m in front of a computer, although they rarely do, and this is exactly why I have this problem…. *shifty eyes*

Anyway, so I think I’ve kind of veered off-topic, except not, because the post was originally about the blog and the rationale for naming, wasn’t it? While I’m at this whole word-vomiting thing, though, I think I will ramble a little more about immunology.

I have a number of allergies, and it’s gotten to the point where I’m tired of just avoiding them and want to try getting rid of them (there are some other reasons and complicating factors, but anyway). I’ve been testing myself for allergies by exposing myself and checking for known reactions, but sometimes it’s hard to tell whether the things I notice are psychosomatic (stress aggravates allergy symptoms, after all) or whether they’re actually physically triggered. I mean, ideally I won’t eat more than the minimum to be sure that it’s an allergic reaction, but it’s kind of hard. Also, it’s somewhat cost-inefficient to obtain food for testing (that is, if I end up not being able to eat it because I am allergic, it’s a waste to just throw the rest away), so I try to do it as the opportunity arises to take part in the eating of $food.

So this plan of getting rid of allergies pretty much involves an elimination diet. I am not convinced that it will work, but I think that it is worth a try, maybe? I’m told that one of the CMEs our freshman year went on an elimination diet for some amount of time (O(1 year), maybe?), and afterwards she could eat anything again. So here’s my reasoning: allergic reactions are generally IgE-mediated. Pharma companies do make anti-IgE antibodies that cause them to be targeted for destruction, but this is generally inadvisable as a course of action for treating food allergies, and IgE antibodies are not terribly well-understood either; they seem to play a role in cancer detection (although the data supporting that theory is inconclusive). The drug is also rather expensive, and your body will just keep producing those antibodies anyway.

From a different angle, then: the half-life of IgE antibodies is approximately 2 days for unbound antibodies and up to several weeks for bound antibodies. Allergens present in the body stimulate T cells, B cells, mast cells, and basophils. T cells and B cells aren’t involved in the acute response, but basically, the T cells stimulate naive B cells to secret antibodies, and then other T cells signal the B cells to switch isotypes and produce IgG, IgA, or IgE antibodies instead of IgD or IgM antibodies, resulting in mature B cells that just churn out antibodies (and daughter B cells that do the same, of course). Mast cells and basophils, which are what actually cause imflammation and other acute reactions, get coated in the IgE antibodies that become bound when the allergen/antigen enters the body. Where am I going with this? Essentially, the idea is to eliminate the cells that play a role in producing the allergic response by not stimulating their proliferation until they die out.

Will it work? I don’t know. The human body has been known to produce antibodies that react to antigens last encountered more than thirty years prior, but not all antibodies hang around that long. And since allergies are so poorly understood…I really just don’t know.

The other possibilities that are out there involve building insensitivity to the antigens, which start off exposing you to small amounts of allergen and increasing the dosage with time to reduce the symptoms of the allergic reaction(s). (It’s  like in Le Comte de Monte Cristo / The Count of Monte Cristo, when M. d’Avrigny gives M. Nortier — who in turn gives Valentine — slowly increasing amounts of poison and the recipient’s system slowly builds resistance, except that was resistance to a toxin/poison, and this is immunotherapy to effect reduced sensitivity.) Sublingual immunotherapy is more widely administered in Europe than in the U.S., but it’s gaining popularity here and seems promising. The other option is allergy injections, which require a long-term commitment and are also not recommended for food allergies; they are generally used to treat pollen/dust/etc allergies, but given that there is a possible connection between food and pollen allergies, it’s certainly worth a try. One of the major concerns with injections, however, is the reason for the long-term commitment: pollen allergies vary by region, so different formulations are used in different areas depending on the local flora. Thus, changing environments that require a different formulation will render the former injection course less effective, and adjustments have to be made, etc etc, that just make it too complicated a problem to deal with unless absolutely necessary; hence, the long-term commitment requirement.

More research is necessary; more testing is necessary; I certainly would rather have a wider set of options open to me while I am on my elimination diet, if at all possible, so eliminating various foods as allergen suspects is tedious, frustrating, painful to some degree, but hopefully useful in the end.

[Edit:] I think that with this skin, writing out “Somatic Hypermutation” doesn’t look as bizarrely unbalanced, so the name of the blog is hereby officially changed! (At least until it lives up to its name, changes its skin, and wants a balanced title again ^_^)

  • By nelhage, December 23, 2009 @ 18:17

    “SHM” definitely binds to “SHared Memory” (As in /dev/shm) for me, not “Simple Harmonic Motion”.

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