Comparison of systemic and local respiratory tract cellular immunity in the neonatal foal

Blood neutrophils from 10 Thoroughbred and 2 Pony foals were evaluated using in-vitro cellular function tests of chemotaxis, chemiluminescence, phagocytosis and intracellular killing. A comparison of the functional capacities of these cells before and 2-4 days after the ingestion of colostrum indicated an improvement in blood neutrophil chemotaxis and chemiluminescence. Bronchopulmonary lavage was carried out on 9 Thoroughbred and 2 Pony 36-h-old foals. The technique used did not require sedation or anaesthesia. Pulmonary alveolar macrophages were the predominant cell type recovered. When comparisons were made between blood neutrophils and pulmonary alveolar macrophages in the same animal fewer pulmonary alveolar macrophages were phagocytic and there was little if any evidence of intracellular killing by pulmonary alveolar macrophages.