Interpretation of eosinophilia in body fluids or tissues is often not straightforward. Eosinophil counts vary among clinically healthy individuals, and considerable overlap can occur between normal and affected animals in conditions such as allergic airway disease. Parasite exposure is a confounding factor when counts are increased, and in cases where very high counts and dramatic clinical signs make another disease process obvious, the underlying pathology may be uncertain and treatment difficult. Eosinophils are a component of the immune response in many diseases of the horse, but their specific role is often unknown and likely multifactorial. In helminth infections, eosinophils are assumed to be part of the normal host response to a pathogen, whereas in multisystemic eosinophilic epitheliotropic disease (MEED), the predominance of eosinophils likely represents a wildly dysregulated response, or an abnormal response altogether. This distinction is still not clear for other diseases. Understanding the pathways involved in recruitment, activation or suppression of eosinophils is required for more accurate diagnostics, effective therapeutics, and successful strategies for prevention of eosinophil associated diseases. Eosinophils of the horse: Part II reviews published observations on the eosinophil in clinical diseases of the horse. The behaviour of eosinophils in three common and relatively well‐studied conditions is presented first, including gastrointestinal helminth infections, non‐infectious respiratory disease, and insect bite hypersensitivity. The less common eosinophil‐associated diseases such as eosinophilic disease confined to the intestine (EDCI) and MEED are considered, followed by a brief summary of the eosinophil in phycomycosis and neoplasia. In conclusion, a panoramic view of the equine eosinophil as presented in Parts I and II is placed in the larger context of current eosinophil research, and areas of study are identified that may improve our understanding of eosinophil biology in equine health and clinical disease.

中文翻译：

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马的嗜酸性粒细胞：第二部分：临床疾病中的嗜酸性粒细胞

体液或组织中嗜酸性粒细胞增多的解释通常并不简单。嗜酸性粒细胞计数在临床健康个体之间有所不同，正常动物和患病动物在诸如过敏性气道疾病等疾病中可能发生大量重叠。当计数增加时，寄生虫暴露是一个令人困惑的因素，并且在很高的计数和显着的临床症状使另一种疾病过程变得明显的情况下，潜在的病理可能不确定且难以治疗。嗜酸性粒细胞是马匹许多疾病免疫反应的组成部分，但其具体作用通常是未知的，可能是多因素的。在蠕虫感染中，嗜酸性粒细胞被认为是正常宿主对病原体反应的一部分，而在多系统性嗜酸性粒细胞上皮性疾病（MEED）中，嗜酸性粒细胞的优势很可能代表了反应异常失调或完全异常反应。对于其他疾病，这种区别仍然不清楚。了解更准确的诊断，有效的治疗方法以及预防嗜酸性粒细胞相关疾病的成功策略，需要了解嗜酸性粒细胞募集，激活或抑制所涉及的途径。马的嗜酸性粒细胞：第二部分综述了有关马的嗜酸性粒细胞在临床疾病中的观察结果。首先介绍了嗜酸性粒细胞在三种常见且研究相对较好的情况下的行为，包括胃肠道蠕虫感染，非感染性呼吸系统疾病和昆虫叮咬过敏。考虑了较不常见的嗜酸性粒细胞相关疾病，例如局限于肠道（EDCI）和MEED的嗜酸性粒细胞疾病，随后简要总结了嗜酸性粒细胞在肺结节病和瘤形成中的作用。总之，在第一部分和第二部分中介绍的马嗜酸性粒细胞的全景图被置于当前嗜酸性粒细胞研究的更大范围内，并且确定了一些研究领域，这些领域可能会增进我们对马嗜酸性粒细胞生物学在马健康和临床疾病中的理解。