Correlation of macrophage migration-inhibition factor and protection from challenge exposure in calves vaccinated...

Migration of bovine macrophages under agarose was used to assess cellular immunity in 7 nonvaccinated calves and 9 calves vaccinated with Salmonella typhimurium. The 9 vaccinated calves were allotted to 4 groups. Group I calves were vaccinated twice orally with small doses of virulent S typhimurium; group II calves were vaccinated twice orally with genetically altered aromatic-dependent (aro-) S typhimurium SL3261; group III calves were vaccinated twice IM with small doses of virulent S typhimurium; and group IV calves were vaccinated twice IM with aro- S typhimurium SL1479. Samples of blood were obtained from these calves at 2 weeks after the 2nd vaccinal dose was given, and lymphocytes were harvested, using lymphocyte separation medium. Lymphocytes in serum-free medium were then incubated with S typhimurim antigen for 48 hours. Lymphocytes were then transferred to antigen-free medium and incubated for 48 hours, and the supernatant was assayed for the migration-inhibition factor (MIF). Lymphocyte supernatant was assayed for MIF by incubating it for 48 hours with 2.0 X 10(4) alveolar macrophages in agar wells. The macrophage migration distance was measured and compared with control values. Macrophage migration was inhibited in the presence of supernatant of lymphocytes from vaccinated calves that had been incubated with antigen, indicating the presence of the MIF in the supernatant. Migration distances, as a percentage of control, were 33% for group I calves (oral vaccination, virulent vaccinal organism), 60% for group II calves (oral vaccination, aro- vaccinal organism), 41% for group III (IM vaccination, virulent organism), and 25% for group IV (IM vaccination, aro- vaccinal organism).(ABSTRACT TRUNCATED AT 250 WORDS)