Horiguchi S, Tanaka Y, Uchida T, Chazono H, Ookawa T, Sakurai D, Okamoto Y
Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
Clin Exp Allergy. 2008 Mar;38(3):405-12. doi: 10.1111/j.1365-2222.2007.02898.x. Epub 2007 Dec 7.
Allergic rhinitis (AR) is a typical type I allergic disease that occurs through the induction of allergen-specific effector T cells. Once established, new effector T cells derive mostly from memory T cells that are capable of surviving for extended periods, although the mechanisms by which these memory functions are maintained have not yet been clarified. In particular, the exact life-span of memory T cells is still not well understood.
Pollinosis patients seemed to be suitable subjects to investigate because such patients are exposed to antigens strongly for only a limited period once a year. We compared the seasonal changes in memory T-helper type 2 (Th2) between pollinosis and perennial allergic subjects.
The clone sizes of the Japanese cedar pollen-specific memory Th cells were measured by an ELISPOT assay using specific peptides from the patients with cedar pollinosis, and the seasonal changes were noted. This study was performed for 2 years. The cedar-specific IgE levels in the peripheral blood were also studied. Mite allergy patients were also enrolled in the study.
The Japanese cedar-specific IL-4-producing Th2 cells were detected in all patients examined, although the number of cells was low. These Th memory cells increased during the pollen season and decreased during the off-season. However, more than 60% of the cedar-specific memory Th2 cells survived up to 8 months after the pollen season. The cedar-specific IgE levels exhibited changes similar to the cedar-specific Th cells. On the other hand, there was no drifting of Th memory clone size with the mite allergics, and the IgE levels also did not change.
While pollen-specific Th cells decreased after pollen exposure, their memory functions continued. Memory clone size maintenance therefore requires repetitive antigen irritation.
变应性鼻炎（AR）是一种典型的Ⅰ型变态反应性疾病，通过变应原特异性效应T细胞的诱导而发病。一旦形成，新的效应T细胞大多来源于能够长期存活的记忆T细胞，尽管维持这些记忆功能的机制尚未阐明。特别是，记忆T细胞的确切寿命仍未得到很好的理解。
花粉症患者似乎是进行研究的合适对象，因为这类患者每年仅在有限的时间段内强烈接触抗原。我们比较了花粉症患者和常年性变应性鼻炎患者之间记忆性辅助性T细胞2型（Th2）的季节性变化。
采用酶联免疫斑点试验（ELISPOT），使用日本柳杉花粉症患者的特异性肽段，测定日本柳杉花粉特异性记忆Th细胞的克隆大小，并记录季节性变化。本研究进行了2年。还对外周血中柳杉特异性IgE水平进行了研究。螨过敏患者也纳入了研究。
在所有检测的患者中均检测到产生日本柳杉特异性白细胞介素-4的Th2细胞，尽管细胞数量较少。这些Th记忆细胞在花粉季节增加，在非花粉季节减少。然而，超过60%的柳杉特异性记忆Th2细胞在花粉季节后存活长达8个月。柳杉特异性IgE水平呈现出与柳杉特异性Th细胞相似的变化。另一方面，螨过敏患者的Th记忆克隆大小没有变化，IgE水平也没有改变。
虽然花粉特异性Th细胞在接触花粉后减少，但其记忆功能仍持续存在。因此，记忆克隆大小的维持需要反复的抗原刺激。
