Application of the direct leukocyte-migration agarose test in cattle naturally infected with Mycobacterium paratuberculosis.

Four cows with persistent diarrhea and complement-fixing antibodies to johnin were examined, using the leukocyte-migration agarose test (LMAT) with johnin as the specific antigen. The diagnosis of paratuberculosis (Johne's disease) was microscopically verified at necropsy. As control animals, 3 healthy cows and 3 cows with disease other than paratuberculosis were examined, using LMAT. The migration indices in the group of cows with paratuberculosis were significantly lower (less than 0.001) than those in the group of control cows. Furthermore, the migration zones of the unstimulated peripheral blood leukocytes in the former group were significantly smaller (less than 0.001) than those of the control group.