Application of a leukocyte migration-inhibition agarose test to swine dysentery.

Cell-mediated immunity (CMI) was demonstrated in swine naturally affected with swine dysentery (SD) by a leukocyte migration-inhibition agarose test (LMAT). Migration of leukocytes from SD-affected pigs was inhibited in the presence of soluble antigen of Treponema hyodysenteriae, whereas migration of leukocytes from noninfected swine was not inhibited by exposure to the same antigen. Cell-mediated immunity was detected initially after the appearance of clinical signs of the disease, and a peak migration index (MI) of 0.11 (P less than 0.01) was detected at 2 weeks thereafter. The MI gradually decreased over the remaining 3 weeks of the experiment. Humoral antibody correlated well with CMI, since both showed maximum production within the same time interval. Leukocytes of swine naturally affected with SD 4 months previously had a significant MI response of 0.73 (P less than 0.05), whereas uninfected swine of comparable age and weight showed a MI of 0.94 that was not significant (P less than 0.05). The results indicated that the LMAT may be useful for the diagnosis of SD.