Only minor differences in signaling molecule expression are observed between nasal polyp-derived CD45RO + T cells and normal donor PBL-derived CD45RO + T cells. In the polyp-derived CD45RO + T cells versus the normal donor peripheral blood CD45RO + T cells, the MFI for CD3ζ (11.6 versus 18.0, NS) and ZAP70 (5.7 versus 6.1, NS) were not significantly different. While there was a statistically significant decrease in the MFI for Lck (39.5 versus 48.6, p < 0.05) and SLP-76 (9.4 versus 11.2, p < 0.05) in the polyp-derived T cells versus T cells from normal donor PBL, the absolute differences in expression of these signaling molecules were small. Results are based upon three independent experiments.