Hanna-Wakim Rima, Yasukawa Linda L, Sung Phillip, Fang Mimi, Sullivan Barbara, Rinki Mary, DeHovitz Ross, Arvin Ann M, Gans Hayley A
Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305-5208, USA.
J Infect Dis. 2009 Dec 15;200(12):1921-7. doi: 10.1086/648375.
The susceptibility of infants to infections is well defined clinically, and immunologic abnormalities have been described. Immune maturation is complex, however, and the interval during which changes occur during childhood has not been identified.
To assess age-related differences in the CD4(+) T cell responses, we evaluated the frequency of CD4(+) T cells that produced interferon (IFN) gamma in response to staphylococcal enterotoxin B (SEB) stimulation in 382 healthy infants and children (2 months to 11 years of age) and 66 adults. Flow cytometry was used to assess SEB-induced CD69 and CD40 ligand (CD40-L) expression and IFN-gamma production by CD4(+) and CD45RO(+)CD4(+) T cells.
CD69 and CD40-L expression by CD4(+) and CD45RO(+)CD4(+) T cells were similar to adult levels from infancy, but the frequency of activated T cells that produced IFN-gamma remained lower than adult responses until children were 10 years of age.
These observations indicate that the IFN-gamma response of CD4(+) T cells to SEB remains limited for a much longer interval than was reported elsewhere, extending to the second decade of life. Observed differences in CD45RO(+)CD4(+) T cell function indicate that CD4(+) T cells with the same phenotypes do not possess equivalent functional capabilities.
婴儿对感染的易感性在临床上已得到明确界定，并且免疫异常也已有相关描述。然而，免疫成熟过程很复杂，儿童期发生变化的时间间隔尚未明确。
为了评估CD4(+) T细胞反应中与年龄相关的差异，我们在382名健康婴儿和儿童（2个月至11岁）以及66名成年人中，评估了因金黄色葡萄球菌肠毒素B（SEB）刺激而产生干扰素（IFN）γ的CD4(+) T细胞的频率。采用流式细胞术评估SEB诱导的CD69和CD40配体（CD40-L）的表达以及CD4(+)和CD45RO(+)CD4(+) T细胞产生IFN-γ的情况。
CD4(+)和CD45RO(+)CD4(+) T细胞的CD69和CD40-L表达从婴儿期起就与成人水平相似，但产生IFN-γ的活化T细胞频率在儿童10岁之前一直低于成人反应。
这些观察结果表明，CD4(+) T细胞对SEB的IFN-γ反应受限的时间间隔比其他地方报道的长得多，一直持续到生命的第二个十年。观察到的CD45RO(+)CD4(+) T细胞功能差异表明，具有相同表型的CD4(+) T细胞并不具备同等的功能能力。
