Prendergast Brian J, Bilbo Staci D, Nelson Randy J
Department of Psychology, The Ohio State University, Columbus, OH 43210, USA.
Am J Physiol Regul Integr Comp Physiol. 2004 Jan;286(1):R54-60. doi: 10.1152/ajpregu.00381.2003. Epub 2003 Sep 4.
Changes in day length affect several measures of immunity in seasonally breeding mammals. In Siberian hamsters (Phodopus sungorus), short day lengths suppress specific secondary antibody responses to the keyhole limpet hemocyanin (KLH) antigen and enhance cutaneous delayed-type hypersensitivity (DTH) responses to dinitrofluorobenzene (DNFB). These experiments tested whether day length affects secondary antibody and DTH responses by altering immune function solely during the interval after the initial exposure to each antigen, solely during the interval after the second exposure, or during both stages of the respective immune responses. Adult male Siberian hamsters were exposed to either a long (16 h light/day; LD) or a short (8 h light/day; SD) photoperiod for 7.5 wk before receiving an initial exposure to each antigen (KLH injection, cutaneous DNFB treatment; separate groups of animals for each antigen). A subset of LD hamsters was transferred to the SD photo-period, and a subset of SD hamsters was transferred to the LD photoperiod. Other hamsters remained in LD or SD. Eight weeks later, all hamsters were challenged with a second subcutaneous injection of KLH or a second application of DNFB to the ear, and immune responses were measured. Exposure to SD during the primary antibody response did not affect secondary IgG responses, but SD exposure during the secondary response significantly suppressed IgG production independent of day length during the initial KLH treatment. In contrast, exposure to SD during the DNFB challenge enhanced the ensuing DTH response, but this enhancement depended on the photoperiod prevailing during the initial exposure. Exposure to SD during the sensitization stage did not enhance DTH in hamsters subsequently exposed to LD. The data suggest that short photoperiods have enduring effects on immune responsiveness and on the establishment and retention of immunological memory.
日照长度的变化会影响季节性繁殖哺乳动物的多种免疫指标。在西伯利亚仓鼠（Phodopus sungorus）中，短日照会抑制对钥孔血蓝蛋白（KLH）抗原的特异性二次抗体反应，并增强对二硝基氟苯（DNFB）的皮肤迟发型超敏反应（DTH）。这些实验旨在测试日照长度是否仅在初次接触每种抗原后的间隔期、仅在第二次接触后的间隔期，或在各自免疫反应的两个阶段通过改变免疫功能来影响二次抗体和DTH反应。成年雄性西伯利亚仓鼠在初次接触每种抗原（注射KLH、皮肤涂抹DNFB；每种抗原使用单独的动物组）之前，先暴露于长日照（16小时光照/天；LD）或短日照（8小时光照/天；SD）光周期7.5周。一部分LD仓鼠被转移到SD光周期，一部分SD仓鼠被转移到LD光周期。其他仓鼠则保持在LD或SD条件下。八周后，所有仓鼠均接受第二次皮下注射KLH或第二次耳部涂抹DNFB的刺激，并测量免疫反应。在初次抗体反应期间暴露于SD对二次IgG反应没有影响，但在二次反应期间暴露于SD会显著抑制IgG产生，且与初次KLH处理期间的日照长度无关。相比之下，在DNFB刺激期间暴露于SD会增强随后的DTH反应，但这种增强取决于初次接触期间的主导光周期。在致敏阶段暴露于SD并不会增强随后暴露于LD的仓鼠的DTH反应。数据表明，短光周期对免疫反应性以及免疫记忆的建立和维持具有持久影响。
