Effect of Prednisolone on Cytokine Synthesis in Nasal Polyps

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Abstract
To investigate steroid effects on eosinophils and their associated cytokines in nasal polyps, we sampled nasal polyp tissue from 20 subjects during routine surgery. Freshley removed polyps were cut into small pieces and incubated in culture medium for 24 h in different concentrations of prednisolone (10 - 2-10 - 6 mol/L). Cell viability was assessed by means of trypan dye exclusion of the supernatants. The number of eosinophils was quantified by means of cytocentrifuge smears stained by May-Giemsa-Grunwald stain. The cytokine protein content of interleukin-5 (IL-5), IL-3, and granulocyte-macrophage colony-stimulating factor (GM-CSF) was measured by ELISA technique in supernatants and in homogenates of nasal polyp tissue. Our results revealed a significant reduction in the number of eosinophils and total number of vital cells at concentrations of 10 - 3 and 10 - 2 mol/L. GM-CSF and IL-5 protein levels were significantly reduced in supernatants and in homogenates after treatment with prednisolone, whereas IL-3 synthesis was not diminished. Corticosteroid effects known to inhibit synthesis of eosinophil-associated cytokines could be measured in terms of a significant decrease in IL-5 and GM-CSF protein level as well as in a decrease in the number of vital cells.