Differences in the expression of the human interferon-γ gene in fresh lymphocytes and cultured lymphoblasts

Fresh human peripheral blood mononuclear lymphocytes and lymphoblasts that had been grown for a period in T-cell growth-factor containing medium were stimulated with staphylococcal enterotoxin A plus mezerein to produce interferon-gamma (IFN-gamma). Growing lymphoblasts produced peak levels of IFN-gamma much earlier after induction than fresh lymphocytes. Quantitation of the steady-state levels of IFN-gamma mRNA showed these to differ markedly between the two cell types over a period of time post-induction. In fresh lymphocytes the steady-state levels of IFN-gamma mRNA increased to a peak level over a period of 4 days while in growing lymphoblasts the peak level occurred after 8 hours. These differences in IFN-gamma mRNA production were shown to be not the result of gross alteration of RNA metabolism following blast transformation.