Interleukin-3 interleukin-5, and granulocyte-macrophage colony-stimulating factor expression in nasal polyps

Nasal polyps (NP) are grape-like clusters of chronically inflamed tissue. Little is known about the underlying cells and cytokines involved in nasal polyposis. For the present study, we hypothesize that elevated tissue levels of interleukin-3 (IL-3), interleukin-5 (IL-5), and granulocyte-macrophage colony-stimulation factor (GM-CSF) contribute to eosinophil recruitment and activation in NP.

To begin to test this hypothesis, we evaluated IL-3, IL-5, and GM-CSF levels and distributions in nasal polyp specimens obtained intraoperatively from 13 patients and two normal controls. For these studies, nasal polyp levels were determined by enzyme-linked immunosorbent assay (ELISA), and IL-3, IL-5, and GM-CSF distribution was determined by immunohistochemistry.

Immunohistochemical staining of the NP indicated that in all 13 patient samples, IL-3, IL-5, and GM-CSF were associated with infiltrating cells, primarily eosinophils, in the NP. Quantitation of IL-3, IL-5, and GM-CSF in NP tissue homogenates indicated that IL-3, IL-5, and GM-CSF levels were evaluated in the NP tissues when compared with control tissues. Additionally, elevation of individual cytokines correlated with previous polypectomy (IL-3), steroid use (IL-3, IL-5, and GM-CSF), asthma (IL-5), and age (GM-CSF).

These data support our hypothesis that IL-3, IL-5, and GM-CSF are likely to play a key role in eosinophil recruitment/activation and NP formation and support recently advanced theories that cytokines play a key role in the pathogenesis of this disease.