免疫系统的记忆力有多长？

　　

生物通报道，免疫系统中有种名为记忆T Cell的细胞，它具有记忆能力，只要遇到过某种病原体，在下一次再遇到时能快速地激活免疫系统发起免疫保护作用，就连我们人类的记忆力也不能和它相比，对于某些事情我们往往很快就会忘记，就算下次再遇到也不见得就记得。

 

人的记忆力有好坏之分，那么免疫系统的记忆力是否也有好坏之分呢？它的记忆能力可延续多长呢？诺华诺德疫苗公司的研究者做了一个这方面的研究，文章发表在最新一期的《美国科学院院报》上。

 

研究者发现，免疫佐剂能提高免疫系统的记忆性，使得免疫细胞的记忆时间延长。Rino Rappuoli主要打算研究禽流感H5N1疫苗的保护周期，给动物注射禽流感抗原后会引起免疫应答，如果只是注射抗原，免疫持久力很短，如果加入佐剂可延长疫苗的作用时间。研究发现加了佐剂抗原疫苗能激发3倍于抗原疫苗的记忆T细胞，这些T细胞的多少就是判断免疫记忆的关键。

 

研究者希望通过更长的时间，至少1年去测量个人对疫苗的免疫记忆，以检测这种疫苗的效果，为临床应用打下基础。如果出现禽流感大规模爆发，就可以通过这种预测疫苗记忆能力的手段评测疫苗生产的进度。尤其是，禽流感病毒变异太快，有了这种测评工具更有利于疫苗的设计。

 

（生物通 小茜）

 

原文摘要：Adjuvanted H5N1 vaccine induces early CD4+ T cell response that predicts long-term persistence of protective antibody levels

【Abstract】

Immune responses to vaccination are tested in clinical trials. This process usually requires years especially when immune memory and persistence are analyzed. Markers able to quickly predict the immune response would be very useful, particularly when dealing with emerging diseases that require a rapid response, such as avian influenza. To address this question we vaccinated healthy adults at days 1, 22, and 202 with plain or MF59-adjuvanted H5N1 subunit vaccines and tested both cell-mediated and antibody responses up to day 382. Only the MF59-H5N1 vaccine induced high titers of neutralizing antibodies, a large pool of memory H5N1-specific B lymphocytes, and H5-CD4+ T cells broadly reactive with drifted H5. The CD4+ response was dominated by IL-2+ IFN-γ− IL-13− T cells. Remarkably, a 3-fold increase in the frequency of virus-specific total CD4+ T cells, measurable after 1 dose, accurately predicted the rise of neutralizing antibodies after booster immunization and their maintenance 6 months later. We suggest that CD4+ T cell priming might be used as an early predictor of the immunogenicity of prepandemic vaccines.