Bet v 1 binds to and is transported through the conjunctival epithelium only in allergic, but not in healthy subjects. Panel a; A conjunctival epithelial biopsy taken from an allergic patient 1 min after the in vivo birch pollen challenge indicated a clear Bet v 1 location detected with anti- Bet v 1 antibodies (green staining for Bet v 1). Original magnification × 200. Panel b; The strong clustered staining of anti-Bet v 1 detected with gold label particles at the epithelial villus. Bet v 1 was seen to co-localise with caveolin 2 as shown with double immunoTEM using an anti- Bet v 1 10 nm gold-labelled antibody and anti-caveolin 2 5 nm gold-labelled antibody, magnification × 27 500. Bet v 1 was almost solely (75%) co-localised with a caveolar marker protein caveolin 2.