Day M J
Division of Veterinary Pathology, Infection and Immunity, School of Clinical Veterinary Science, University of Bristol, Langford, North Somerset, UK.
J Comp Pathol. 2010 Jan;142 Suppl 1:S60-9. doi: 10.1016/j.jcpa.2009.10.011. Epub 2009 Dec 14.
Improvements in veterinary healthcare over recent decades mean that we now have a significant population of geriatric small companion animals. The design of optimum nutritional and vaccination programmes for these aged animals must be underpinned by knowledge of the physiological changes that occur in later life. It is clear that older dogs and cats are affected by the process of immunosenescence and that similar changes occur in these species to those documented in elderly people. The most consistent findings of recent investigations indicate impairment of cell-mediated immune function with age. Senior dogs and cats are generally shown to have reduced blood CD4(+) T cells (with imbalance in Th1 versus Th2 functional activity), elevation in the CD8(+) subset and reduction in the CD4:CD8 ratio. The ability of blood lymphocytes to respond to stimulation by mitogens decreases, as does the cutaneous delayed type hypersensitivity response. By contrast, there is relative preservation of the ability to mount humoral immune responses. Serum and salivary immunoglobulin (Ig)A production increases and IgG concentration remains unaltered with age. Elderly animals generally have persisting vaccinal antibody titres at protective level and respond to booster vaccination with elevation in titre. Older dogs and cats are able to make primary humoral responses to novel antigens, but the magnitude of these may be reduced relative to titres achieved in younger animals. Fewer investigations have studied the phenomenon of 'inflammageing' (the effect of cumulative antigenic exposure and onset of late life inflammatory disease) in these species. Senior cats have increased production of pro-inflammatory cytokines by blood monocytes, but this effect has not been demonstrated with cells derived from older dogs. Numerous studies have investigated whether canine and feline immunosenescence might be slowed or reversed by dietary supplementation with antioxidants, but no significant research has addressed the need for geriatric vaccination protocols.
近几十年来兽医保健水平的提高意味着我们现在有大量老年小型伴侣动物。为这些老龄动物设计最佳营养和疫苗接种方案必须基于对晚年发生的生理变化的了解。显然，老年犬猫会受到免疫衰老过程的影响，并且这些物种中发生的变化与老年人中记录的变化相似。最近调查最一致的结果表明，细胞介导的免疫功能会随着年龄增长而受损。老年犬猫通常表现为血液中CD4(+) T细胞减少（Th1与Th2功能活性失衡），CD8(+)亚群升高，CD4:CD8比值降低。血液淋巴细胞对有丝分裂原刺激的反应能力下降，皮肤迟发型超敏反应也下降。相比之下，体液免疫反应能力相对保留。血清和唾液免疫球蛋白（Ig）A的产生增加，IgG浓度随年龄增长保持不变。老年动物通常具有持续处于保护水平的疫苗抗体滴度，并对加强免疫接种产生滴度升高的反应。老年犬猫能够对新抗原产生初次体液反应，但相对于年轻动物达到的滴度，这些反应的强度可能会降低。较少有研究探讨这些物种中的“炎症衰老”现象（累积抗原暴露和晚年炎症性疾病发作的影响）。老年猫血液单核细胞产生促炎细胞因子的量增加，但这种效应在老年犬的细胞中尚未得到证实。许多研究调查了通过补充抗氧化剂的饮食是否可以减缓或逆转犬猫的免疫衰老，但没有重要研究涉及老年疫苗接种方案的必要性。
