IL-12 synergizes with IL-2 to induce lymphokine-activated cytotoxicity and perforin and granzyme gene expression in fresh human NK cells.
NK-mediated cytotoxicity is regulated by a variety of cytokines and is thought to involve perforin and granzymes. The effects of IL-2 and IL-12 on the expression and activation of cytolysis were examined in freshly isolated human NK cells. A dose-dependent increase in cytolysis of the NK-sensitive target cell, K562, and the NK-insensitive but lymphokine-activated killer (LAK) cell-sensitive target, UCLA-SO-M14, was observed after short term culture of purified human NK cells in either IL-2 or IL-12. Moreover, the two cytokines often synergized to produce augmented lytic activity. A suboptimal dose of IL-2 (60 IU/ml) combined with IL-12 (2 U/ml) could induce lytic activity equal to twice the additive effect of each cytokine alone. Northern analyses revealed time-dependent increases in mRNAs encoding for perforin and granzymes A and B following treatment with IL-2 alone or IL-2 plus IL-12. IL-2 and IL-12 also synergized for the induction of granzyme mRNAs, in that treatment with both cytokines increased mRNA levels approximately 50% above the sum of each cytokine alone, as quantitated by phosphorimage analysis, and normalized to GAPDH gene expression. However, the synergy between IL-2 and IL-12 for the induction of mRNA was less dramatic than for lytic activity. Results of experiments in which cytokine-treated cells were pulsed with actinomycin D indicated that the increased granzyme and perforin gene mRNA levels in response to IL-2, IL-12, or the combination were not due to increased transcript stability. The data suggest that low doses of IL-2 and IL-12 synergize to augment NK- and induce LAK-mediated cytotoxicity and that this increase is associated with enhanced transcription of perforin and granzyme genes in a synergistic fashion.
DeBlaker-Hohe
D F
DF
Laboratory of Cellular Immunology, Food and Drug Administration, Bethesda, Maryland 20892, USA.
Yamauchi
A
A
Yu
C R
CR
Horvath-Arcidiacono
J A
JA
Bloom
E T
ET
D002478:Cells, Cultured; D004357:Drug Synergism; D015870:Gene Expression; D053804:Granzymes; D006801:Humans; D018664:Interleukin-12 / Q000494:pharmacology*; D007376:Interleukin-2 / Q000494:pharmacology*; D015979:Killer Cells, Lymphokine-Activated / Q000187:drug effects / Q000502:physiology*; D007694:Killer Cells, Natural / Q000502:physiology; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics*; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger / Q000032:analysis; D012697:Serine Endopeptidases / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics*
D007376:Interleukin-2; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger; D054353:Perforin; D018664:Interleukin-12; D053804:Granzymes; D012697:Serine Endopeptidases; C509212:GZMA protein, human