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Induction of IL-8 gene expression in human polymorphonuclear neutrophils by recombinant IL-2
S Wei1, J H Liu, D K Blanchard
1H. Lee Moffitt Cancer Center, University of South Florida College of Medicine, Department of Medical Microbiology, Tampa 33612.
Abstract:
Induction of IL-8 gene expression was investigated in IL-2-stimulated circulating peripheral blood polymorphonuclear neutrophils (PMN). Brief exposure of normal PMN to human rIL-2 enhanced both transcriptional and translational expression of IL-8. The IL-8 mRNA was first detectable by 3 h, followed by a continuous maintenance of high mRNA levels up to 18 h. Maximal transcription was obtained with 1000 U/ml of IL-2, which achieved the level observed with known neutrophil-activating factors such as granulocyte macrophage-CSF and Candida albicans. The protein synthesis inhibitor, cycloheximide, had no detectable effect on levels of IL-8 mRNA expression in PMN incubated in medium alone; however, cycloheximide could selectively modulate IL-8 mRNA transcription in PMN, depending on the cytokine used. Cycloheximide did not affect or alter IL-8 mRNA induction in IL-2-treated PMN but abrogated it in granulocyte macrophage-CSF-treated PMN and super-induced the level of IL-8 mRNA in C. albicans-treated PMN. Of significance was the observation that IL-2 has no direct chemotactic effect on PMN, whereas the cell-free supernatants from IL-2-stimulated PMN show potent chemotaxis for freshly isolated PMN, which can be specifically blocked by anti-IL-8 Abs. These findings suggested that the induction of IL-8 gene expression in PMN by IL-2 may be involved in the recruitment of PMN into tissues during local IL-2 therapy in human cancer and in part contribute to tumor rejection.
Insights
Interleukin-2 (IL-2) stimulates the gene expression of Interleukin-8 (IL-8) in polymorphonuclear neutrophils (PMN). This IL-8 induction by IL-2 in PMN may contribute to immune cell recruitment in cancer therapy.
Area of Science:
- Immunology
- Molecular Biology
- Cancer Research
Background:
- Interleukin-2 (IL-2) is a cytokine used in cancer therapy.
- Polymorphonuclear neutrophils (PMN) are key immune cells involved in inflammation and host defense.
- The role of IL-2 in modulating PMN function, specifically IL-8 gene expression, requires further elucidation.
Purpose of the Study:
- To investigate the effect of IL-2 on IL-8 gene expression in human PMN.
- To determine the kinetics and optimal concentration of IL-2 for IL-8 induction.
- To explore the interaction of IL-2-induced IL-8 with other neutrophil-activating factors and protein synthesis inhibitors.
Main Methods:
- Human peripheral blood PMN were stimulated with recombinant human IL-2 (rIL-2).
- IL-8 mRNA levels were assessed over time using molecular techniques.
- The effect of cycloheximide, a protein synthesis inhibitor, on IL-8 mRNA expression was evaluated.
- Chemotaxis assays were performed using supernatants from IL-2-stimulated PMN.
Main Results:
- IL-2 significantly enhanced both transcriptional and translational expression of IL-8 in PMN.
- IL-8 mRNA was detectable within 3 hours and sustained up to 18 hours post-stimulation.
- Maximal IL-8 induction was observed at 1000 U/ml of IL-2.
- Cycloheximide modulated IL-8 mRNA differently depending on the stimulus, but did not affect IL-2-induced IL-8 mRNA levels.
- IL-2 alone did not exhibit chemotactic activity, but supernatants from IL-2-stimulated PMN showed potent PMN chemotaxis, blocked by anti-IL-8 antibodies.
Conclusions:
- IL-2 effectively induces IL-8 gene expression in PMN.
- The mechanism of IL-8 induction by IL-2 in PMN is distinct from that of other factors like G-CSF and C. albicans.
- IL-2-induced IL-8 production by PMN may play a role in recruiting immune cells to tumor sites during IL-2 therapy, potentially contributing to tumor rejection.