Sandström Cecilia A M, Prop Jouke, van der Jeugd Henk, Loonen Maarten J J E
University of Groningen, Arctic Centre, PO Box 716, 9700 AS Groningen, the Netherlands; University of Groningen, Ocean Ecosystems, Nijenborgh 7, 9747 AG Groningen, the Netherlands.
University of Groningen, Arctic Centre, PO Box 716, 9700 AS Groningen, the Netherlands.
PLoS One. 2014 Dec 17;9(12):e114812. doi: 10.1371/journal.pone.0114812. eCollection 2014.
Variation in immune defence in birds is often explained either by external factors such as food availability and disease pressure or by internal factors such as moult and reproductive effort. We explored these factors together in one sampling design by measuring immune activity over the time frame of the moulting period of Arctic-breeding barnacle geese (Branta leucopsis). We assessed baseline innate immunity by measuring levels of complement-mediated lysis and natural antibody-mediated agglutination together with total and differential leukocyte counts. Variation in immune activity during moult was strongly associated with calendar date and to a smaller degree with the growth stage of wing feathers. We suggest that the association with calendar date reflected temporal changes in the external environment. This environmental factor was further explored by comparing the immune activity of geese in the Arctic population with conspecifics in the temperate climate zone at comparable moult stages. In the Arctic environment, which has a lower expected disease load, geese exhibited significantly lower values of complement-mediated lysis, their blood contained fewer leukocytes, and levels of phagocytic cells and reactive leukocytes were relatively low. This suggests that lower baseline immune activity could be associated with lower disease pressure. We conclude that in our study species, external factors such as food availability and disease pressure have a greater effect on temporal variation of baseline immune activity than internal factors such as moult stage.
鸟类免疫防御的变化通常要么由食物可获得性和疾病压力等外部因素来解释，要么由换羽和繁殖努力等内部因素来解释。我们通过在北极繁殖的黑雁（Branta leucopsis）换羽期的时间框架内测量免疫活性，在一个抽样设计中共同探究了这些因素。我们通过测量补体介导的细胞溶解水平、天然抗体介导的凝集以及白细胞总数和分类计数来评估基础先天性免疫。换羽期间免疫活性的变化与日历日期密切相关，与翼羽生长阶段的相关性较小。我们认为与日历日期的关联反映了外部环境的时间变化。通过比较北极种群的鹅与温带气候区处于类似换羽阶段的同种鹅的免疫活性，进一步探究了这一环境因素。在预期疾病负荷较低的北极环境中，鹅的补体介导的细胞溶解值显著较低，其血液中的白细胞较少，吞噬细胞和反应性白细胞水平相对较低。这表明较低的基础免疫活性可能与较低的疾病压力有关。我们得出结论，在我们的研究物种中，食物可获得性和疾病压力等外部因素对基础免疫活性的时间变化的影响大于换羽阶段等内部因素。
