Mikita Cecilia P, Padlan Eduardo A
Department of Allergy and Immunology, Walter Reed Army Medical Center, Washington, DC, USA
Med Hypotheses. 2007;69(5):1070-3. doi: 10.1016/j.mehy.2006.12.060. Epub 2007 May 7.
Tropomyosin is a major allergen in various foods, implicated in a spectrum of mild to life threatening systemic reactions. The incidence of allergy to tropomyosin varies greatly by species, with sensitivity to crab, shrimp, cockroach, and dust mite tropomyosins, among others, being the highest, while tropomyosins in vertebrate species are considered non-allergenic. We have analyzed the possible fragments which may result from Pepsin A digestion of tropomyosins from various species and find that larger fragments of the tropomyosins from crab, shrimp, cockroach, and especially, dust mites will probably survive gastric digestion, compared to those from, for example, chicken, cattle, rabbit, or fish. These larger peptide fragments may enter the bloodstream and assume a three-dimensional structure whose stability approaches that of the intact molecule. Antibodies, including IgE, would be expected to be produced specifically against stable regions of the tertiary structure. We propose that this is a plausible explanation for the greater ability of the larger molecules derived from invertebrate tropomyosins to trigger an immediate hypersensitivity response.
原肌球蛋白是多种食物中的主要过敏原，与一系列从轻度到危及生命的全身反应有关。对原肌球蛋白过敏的发生率因物种而异，其中对蟹、虾、蟑螂和尘螨等的原肌球蛋白敏感性最高，而脊椎动物物种中的原肌球蛋白被认为无致敏性。我们分析了各种物种的原肌球蛋白经胃蛋白酶A消化后可能产生的片段，发现与来自鸡、牛、兔或鱼等的原肌球蛋白相比，蟹、虾、蟑螂尤其是尘螨的原肌球蛋白的较大片段可能在胃消化后存活下来。这些较大的肽片段可能进入血液并呈现出一种三维结构，其稳定性接近完整分子。预计会产生包括IgE在内的抗体，专门针对三级结构的稳定区域。我们认为，这是对无脊椎动物原肌球蛋白衍生的较大分子引发速发型超敏反应能力更强的一种合理的解释。
