The role of the alveolar macrophage in jaagsiekte

The increase of alveolar macrophages in jaagsiekte sheep lungs is not caused by excessive surfactant production but is due to a chemotactic factor secreted by the tumour cells. Both growth inhibitory and growth stimulatory factors were detected in vitro in medium from cultures of lung lavage cells exposed to jaagsiekte tumour cell supernatant. The macrophage component of the lavage cells was found to produce a growth stimulatory factor that was replaced by a growth inhibitory factor following exposure to jaagsiekte tumour cell supernatant. Whether these factors stimulated or inhibited DNA synthesis depended to some extent on whether the indicators cells were transformed or not. Alveolar macrophages infected with lentivirus were found to be chemotactically inhibited as well as having a reduced leukocine production potential. Peripheral blood monocytes isolated from sheep suffering with acute jaagsiekte were depressed with regard to their DNA synthesis potential. 3H-thymidine incorporation assay was used to determine if there was any difference in the division potential of blood monocytes isolated from JS-sheep compared to normal sheep