title: In vitro phagocytosis and killing of Corynebacterium equi by alveolar macrophages of foals.
abstract: Bronchoalveolar lavage was performed 5 times, sequentially, on 3 healthy foals while each foal was 6 to 63 days of age. Phagocytosis and bactericidal assays were performed on recovered alveolar macrophages. Corynebacterium equi and alveolar macrophages at a ratio of 10:1 were incubated for 1 hour in medium containing 1% heat-inactivated rabbit anti-C equi serum. After incubation, greater than 90% of the alveolar macrophages contained at least 1 ingested bacterium and each alveolar macrophage contained 9.4 +/- 1.0 bacteria (mean +/- SE). After alveolar macrophages and C equi were incubated for 1 hour in medium containing heat-inactivated pooled normal horse serum, approximately 24% of the alveolar macrophages contained at least 1 bacterium and each alveolar macrophage contained 0.8 +/- 0.7 bacteria. From 6 to 61 days of age, each foal had significantly (P less than 0.05) decreased phagocytic activity by alveolar macrophages, but a significant change in killing of C equi by alveolar macrophages was not found in the foals from 21 to 61 days of age. After incubating alveolar macrophages and C equi for 4 hours in vitro, approximately 75% of ingested C equi remained viable.
mesh_terms: D000818:Animals; D003354:Corynebacterium Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D006734:Horse Diseases / Q000276:immunology* / Q000473:pathology; D006736:Horses; D008264:Macrophages / Q000276:immunology*; D010587:Phagocytosis; D011650:Pulmonary Alveoli / Q000276:immunology