Bovine interleukin 2: production kinetics in normal and in vivo antigen-primed cattle

Conditions influencing production kinetics of bovine interleukin 2 (IL-2), viz. cell concentration, mitogen and its concentration, length of incubation, nutrient medium and in vivo antigen-priming were investigated. Peripheral blood mononuclear cells (PBL) of outbred cattle of different age groups showed considerable variation in their ability to secrete IL-2 which possibly reflects their immune competence. Of the cultures initiated with PBL, 5 x 10(6) cells/ml cultured in serum free Iscove's medium and stimulated with 5 micrograms Con A/ml for 24 hr produced maximal amount of IL-2 activity. In vivo antigen-priming of bovine lymphocytes with the live attenuated rinderpest virus revealed that IL-2 production was not affected by rinderpest virus but the in vivo antigen-priming possibly resulted in concomitant production of suppressor factor(s) which suppressed the already produced IL-2. The implications of this factor(s) in relation to regulation of immune responses in the disease process are discussed.