The first-line effector mechanisms of immune defence, including inflammation and oxidative burst, contribute significantly to host-pathogen resistance. Whether these immune responses undergo age-related changes in birds remains unknown. Here, we tracked selected inflammatory parameters in 54 free-living great tits (Parus major) of known age, captured repeatedly over three consecutive years, with the aims to investigate long-term repeatability and age-dependent changes in cellular oxidative burst responsiveness upon in vitro stimulation with bacterial lipopolysaccharide (LPS), and to identify its relationships with leukotriene B4 (LTB4) levels and haematological traits. In addition, we linked these immunological traits to selected physiological markers (antioxidants and oxidative stress markers). LTB4 levels increased with age and we have shown a similar non-significant tendency also for absolute granulocyte counts, indicating propagating chronic inflammation over the bird's lifetime, consistent with the inflammaging hypothesis. In contrast, cellular oxidative burst followed a quadratic trend of dependency on age with a peak in midlife individuals, in line with the immunosenescence hypothesis. Interestingly, LTB4 levels were positively associated with general oxidative damage, but negatively with antioxidant glutathione peroxidase activity, indicating links to redox balance. This longitudinal study demonstrates the contrasting patterns of age-related changes in background and acute markers of pro-inflammatory immunity contributing to immunosenescence in birds and thus provides basis for interpretation of the tested inflammatory markers in cross-cohort datasets.

免疫防御的一线效应机制，包括炎症和氧化爆发，对宿主病原体抗性有显着贡献。这些免疫反应是否会在鸟类中发生与年龄相关的变化仍然未知。在这里，我们追踪了 54 只自由生活的大山雀（Parus major) 已知年龄，连续三年重复捕获，目的是研究细菌脂多糖 (LPS) 体外刺激后细胞氧化爆发反应的长期可重复性和年龄依赖性变化，并确定其与白三烯 B4 的关系(LTB4) 水平和血液学特征。此外，我们将这些免疫学特征与选定的生理标志物（抗氧化剂和氧化应激标志物）联系起来。LTB4 水平随着年龄的增长而增加，我们也对绝对粒细胞计数显示出类似的非显着趋势，表明在鸟类的一生中传播慢性炎症，与炎症假设一致. 相比之下，细胞氧化爆发遵循与年龄相关的二次趋势，在中年个体中达到峰值，这与免疫衰老假说一致。有趣的是，LTB4 水平与一般氧化损伤呈正相关，但与抗氧化谷胱甘肽过氧化物酶活性呈负相关，表明与氧化还原平衡有关。这项纵向研究证明了与年龄相关的背景变化和促炎免疫急性标志物的对比模式，有助于鸟类免疫衰老，从而为跨队列数据集中测试的炎症标志物的解释提供了基础。