Age-related alteration of immune functions in humans and its relation to autoimmunity

我们对24例老年人(平均79.3岁)的B淋巴细胞功能进行了评估。14名年轻人(平均24.5岁)人。与年轻人的淋巴细胞相比，老年人的淋巴细胞在金黄色葡萄球菌刺激下掺入氚胸腺嘧啶核苷的量明显减少。此外，老年人自发分泌免疫球蛋白(Ig)的细胞数量增加。然而，经商陆有丝分裂原刺激的老年人淋巴细胞产生的免疫球蛋白与年轻人相同。在老年人中的结果与活体多克隆B细胞激活一致。25名老年人(70-80岁)的中性粒细胞。来自15名年轻人(&lt；50岁)接下来对它们产生趋化活性、吞噬活性和氧中间体的能力进行了研究。来自老年捐献者的中性粒细胞产生的趋化活性比来自年轻捐赠者的中性粒细胞更少。相比之下，年轻和老年捐赠者的中性粒细胞吞噬活性和氧气中间体的产生是相似的。与衰老相关的中性粒细胞选择性趋化能力的丧失可能导致感染性疾病的发病率随年龄的增加而增加。由于肿瘤的发病率随年龄的增加而增加，人们可以预期老年人的NK活性会受到损害。然而，尽管65岁至70岁和86岁以上的年龄组的NK活性与年轻人(18岁至50岁)相似，但在71岁至75岁、76岁至80岁和81岁至85岁的年龄组中显示出NK活性的增加。观察到的NK细胞活性的差异不能归因于老年人和年轻人血液中NK细胞百分比的差异。随着年龄的增加，NK细胞活性的增加可能弥补了免疫功能随年龄的下降，维持正常免疫系统的动态平衡。

We evaluated B lymphocyte function in 24 elderly (mean 79.3 yr.) and 14 young (mean 24.5 yr.) persons. Lymphocytes from elderly persons incorporated significantly less tritiated thymidine as compared with lymphocytes from young persons when stimulated with Staphylococcus aureus Cowan I. Moreover, the elderly persons were found to have elevated numbers of cells spontaneously secreting immunoglobulin (Ig). However, lymphocytes from elderly persons stimulated with pokeweed mitogen displayed Ig production equal to young persons. The results in elderly persons are consistent with polyclonal B cell activation in vivo.Neutrophils from 25 elderly persons (70 to 80 yr.) and from 15 young persons (<50 yr.) were next investigated for their ability to produce chemotactic activity, phagocytic activity and oxygen intermediates. Neutrophils from old donors produced less chemotactic activity than did neutrophils from young donors. In contrast, phagocytic activity and production of oxygen intermediates by neutrophils from young and old donors were comparable. The selective failure in the chemotaxis of neutrophils associated with aging could contribute to the increase with age in the incidence of infectious diseases.Because of the increase with age in the incidence of neoplasia, one can expect impaired NK activity in aged humans. However, increase in NK activity was demonstrated in groups aged 71 to 75, 76 to 80 and 81 to 85, although groups of 65 to 70 years and more than 86 years showed a comparable NK activity to that in young persons (18 to 50 years). The difference in observed NK activity could not be attributed to differences in percentage of NK cells in the blood from old and young persons. Increase with age in the NK activity may make up the decline of immunologic competence with age for maintaining normal immune system homeostasis.