8月3日,，刊登在國際著名雜志Trends in Genetics上的一篇研究報(bào)告指出，人類的HLA（組織相容性抗原）基因進(jìn)化比科學(xué)家認(rèn)為的要快得多,。這種進(jìn)化上的改變可以改變我們抵御疾病的能力,，HLA基因可以允許我們自身免疫系統(tǒng)區(qū)分自身細(xì)胞和外來侵入者。
HLA蛋白位于人類細(xì)胞表面,，每一個(gè)個(gè)體在其細(xì)胞表面都有特異性的HLA蛋白,，這些蛋白質(zhì)可以扮演身份證的作用。擁有相同HLA的其它細(xì)胞被認(rèn)為是自身細(xì)胞,，外來的病毒或者細(xì)菌被認(rèn)為是外來入侵者,，免疫系統(tǒng)會(huì)及時(shí)識(shí)別并將其清理掉，我們的機(jī)體對于移植入的組織視為外來者,，因此拒絕其的加入,，除非病人和捐獻(xiàn)者的HLA基因相同，因此,，全世界的科學(xué)家正在努力去尋找可能的HLA突變體,，希望提高病人和捐獻(xiàn)者配對成功率。
HLA的突變非?？焖?，研究者在現(xiàn)在的人口中建立了超過100萬的突變體。盡全力去識(shí)別所有的突變體幾乎不可能,，因?yàn)檫@些基因進(jìn)化的速度非常之快,。當(dāng)然了快速進(jìn)化從某種意義上來說也是一種方便，因?yàn)檫@意味著,，在人口水平上,，我們的免疫系統(tǒng)變得更加可以抵御致病菌的感染了,。對于移植器官接受者來說，配對成功的最佳機(jī)會(huì)是在一級(jí)親屬中尋找,，而不是在全世界范圍內(nèi)尋找合適的捐獻(xiàn)者,。
（生物谷Bioon.com）
編譯自：Unexpected Variation in Immune Genes Poses Difficulties for Transplantation
doi:10.1016/j.tig.2012.06.007
PMC:
PMID:
New reservoirs of HLA alleles: pools of rare variants enhance immune defense
William Klitz1, , Philip Hedrick2, Edward J. Louis3
Highly polymorphic exons of the major histocompatibility complex (MHC, or HLA in humans) encode critical amino acids that bind foreign peptides. Recognition of the peptide–MHC complexes by T cells initiates the adaptive immune response. The particular structure of these exons facilitates gene conversion(GC) events, leading to the generation of new alleles. Estimates for allele creation and loss indicate that more than 10 000 such alleles are circulating at low frequencies in human populations. Empirical sampling has affirmed this expectation. This suggests that the MHC loci have a system for moving valuable and often complex variants into adaptive service. Here, we argue that HLA loci carry many new mutant alleles prepared to assume epidemiologically meaningful roles when called on by selection provoked by exposure to new and evolving pathogens. Because new mutant alleles appear in a population at the lowest possible frequency (i.e., a single copy), they have typically been thought of as having little consequence. However, this large population of rare yet potentially valuable new alleles may contribute to pathogen defense.
