Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site aecom.UUCP Path: utzoo!linus!philabs!aecom!werner From: werner@aecom.UUCP (Craig Werner) Newsgroups: net.med,net.kids Subject: Re: Allergies (Some basic immunological facts) Message-ID: <1599@aecom.UUCP> Date: Wed, 15-May-85 23:25:20 EDT Article-I.D.: aecom.1599 Posted: Wed May 15 23:25:20 1985 Date-Received: Fri, 17-May-85 02:51:55 EDT References: <211@unc.UUCP> Organization: Albert Einstein Coll. of Med., NY Lines: 41 Xref: linus net.med:1355 net.kids:1215 Some facts on allergies from a future immunologists: Allergies are caused by an improper immune reaction by the body. The official term for it is Type I (immediate) hypersensitivity. The are several types of Antibodies in the blood. IgG is the most common, IgA is found in mucus, and IgE is responsible for Allergies. IgE binds to cells in the skin and other places called Mast Cells. When an allergen (anything that causes Allergy) comes in contact with the IgE on the mast cells, it causes the Mast Cells to degranulate. Degranulating Mast Cells release Histamine, Serotonin, Slow Reacting Substance of Anaphylaxis. These cause blood vessels to dilate and tissues to swell and various other effects. If local, it causes a rash. If it gets into the blood in a big way, Anaphylactic shock, which is pretty nasty, can occur (such as a person dying from a bee sting.) To test for allergies, there are new alternatives to simple scratch tests. One - the RAST test looks for Antigen-reactive IgE in the blood. (However, just because you have IgE that binds to Ragweed doesn't mean you'll be allergic to it. On the other hand, you can't be allergic to it if you're IgE doesn't bind it. So it's a quick easy way to rule out a lot of things.) Then there is hyposensitization. This works as follows. IgG and IgA can also bind allergens, and if they do, don't cause the allergy response. However, most people don't make enough of these two during allergies, so the IgE predominates. If you can induce a response, then the competition between the various antibodies will prevent the allergy. This doesn't work for all antigens. SOme don't respond. For these, a person could be given anti-Allergen antibodies in lieu of making them herself, however this passive protection only lasts weeks, not years, and there may be a transfusion reaction. Incidentally, there is a condition known as Atopy, which is a genetic predisposition to make a lot of IgE. Although the actual allergy is not inherited, the disposition to be allergic to SOMETHING is. Hope that's good enough explanation of the situation. -- Craig Werner !philabs!aecom!werner What do you expect? Watermelons are out of season!