Evidence for two discrete phases of IL-2 production in bovine lymphocytes

Regulation of IL-2 production in Con A-stimulated bovine lymph node cells was studied by following the time course of IL-2 synthesis and secretion over a 24-h period. A biphasic time course curve of IL-2 secretion was observed after stimulation with Con A alone or with Con A plus PMA. Both phases of IL-2 production were confirmed by three separate biochemical techniques: IL-2 protein bioassay, mRNA Northern blots, and anti-IL-2 antibody detection. Bovine IL-2 transcripts were detected as early as 2 h after Con A stimulation. The early phase of IL-2 protein secretion was initially detected 3 h after Con A stimulation, and the late phase occurred between 10 and 16 h. Both phases of IL-2 production were enhanced when PMA was added to the Con A stimulation. Each phase of IL-2 protein secretion was preceded by the accumulation of IL-2 mRNA.