Effects of subclinical bovine paratuberculosis on in-vitro polymorphonuclear neutrophil migration

Migration of polymorphonuclear neutrophils (PMNs) [unstimulated or stimulat ed with zymosan-activated serum (ZAS)] from 18 cows was measured in a micro well filter assay. Of these animals, 10 were subclinically infected with My cobacterium paratuberculosis and shown by culture to be excreting the organ ism in the faeces; the remaining eight were clinically normal and negative for M. paratuberculosis on faecal culture. PMN "net migration" (stimulated minus unstimulated cells) of the infected cows was significantly lower than that of the uninfected cows. Migration of unstimulated cells in the infect ed cows did not differ from that in the uninfected cows. It would therefore appear that the infection influenced only the migratory response of the ZA S-stimulated cells. (C) 1999 Harcourt Publishers Ltd.