SEQUENTIAL EXPRESSION OF LYMPHOKINE GENES DURING PHYTOHEMAGGLUTININ-STIMULATED MITOGENESIS OF NORMAL HUMAN PERIPHERAL MONONUCLEAR-CELLS

Expression of lymphokine genes including interleukin 2 (IL-2), interle ukin 3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CS F), interferon gamma (IFN-g), tumor necrosis factor (TNF) and lymphoto xin (LT) were sequentially monitored in peripheral blood mononuclear c ells by Northern blot analysis after stimulation with phytohemagglutin in (PHA). The pattern of the expression of lymphokine genes following PHA stimulation as categorized into two types. Type 1 was characterize d by rapid appearance of mRNA and by early maximum accumulation. Type 2 was characterized by the prolonged expression and late peak time. Ly mphokines including IL-2, IL-3 and GM-CSF belong to type 1 and IFN-g, TNF and LT belong to type 2. Since lymphokines in type 1 are known to act on hematopoiesis in a stimulatory manner, whereas type 2 show an i nhibitory action, this sequential expression of lymphokines following mitogen stimulation may reflect some biological feedback mechanism.