Paraffin-embedded sections of human colon from CD patients and controls were cut (5 μm) and deparaffinized. For immunohistochemistry, sections were microwaved for 2 × 5-min cycles in 10 mM citrate buffer, and processed by ABC method according to the manufacturer’s protocol (Vectastain ABC kit; Vector Laboratories, Burlingname, CA, USA). Sections were incubated with rabbit anti-CRTH2 (1:200; Acris Antibodies, Herford, Germany) 11 (link), visualized with 3-3′-diaminobenzidine (DAB) and counterstained with hematoxylin. CD4+ T cells were stained with a monoclonal mouse anti-human CD4 (clone 4B12; dilution 1:20; Labvision, Fremont, USA) as recommended by the suppliers. Images were taken with a high resolution digital camera (Olympus DP 50) and analyzed by Cell^A imaging software (Olympus, Vienna, Austria). Only contrast and brightness of images were adjusted. Sirius Red (Direct Red 80®, Sigma) was used to stain eosinophils in deparaffinized sections.