Suppression of specific lymphocyte blastogenesis after intravenous tuberculin injection in Mycobacterium bovis-sensitized cattle.

Intravenous injection of 1.0 ml of old tuberculin (OT) in 4 calves previously sensitized to Mycobacterium bovis resulted in suppression of specific lymphocyte blastogenic responses to purified protein in vitro. Suppression of in vitro blastogenic responses occurred within 24 hours after injection of OT and persisted for up to 96 hours. Lymphocytes from these calves, cultured with concanavalin A, did not show any suppression of the lymphocyte blastogenic response in vitro. Suppression was temporary and in all calves was preceded by rapid febrile responses. Rectal temperature responses ranged from 40.1 to 41.6 C as early as 6 hours after tuberculin injections. Three control animals, M bovis-sensitized but not given OT, remained lymphocyte stimulation-positive throughout the study and served as controls for laboratory fluctuations.