Migration-inhibition response of peripheral leukocytes to tuberculin in cats sensitized with viable Mycobacterium bovis (BCG).

Delayed hypersensitivity reactions to antigens injected intradermally are reported as not occurring in the cat. Cats infected with viable Mycobacterium bovis (BCG) organisms developed a transient migration-inhibition response of their leukocytes to tuberculin. The migration-inhibition response subsided in 6 weeks in spite of the persistance of viable BCG. Significant intradermal reactions to tuberculin 60 days after BCG injection did not occur. The response of the cat differs from that of many mammalian species in which strong in vivo and in vitro delayed hypersensitivity type reactions persist with mycobacterial infections. Despite the lack of continued measurable delayed hypersensitivity, the cat appears to have adequate resistance to mycobacterial infections.