[1] ERASMUS UNIV, DEPT OTORHINOLARYNGOL, 3000 DR ROTTERDAM, NETHERLANDS
[2] SWISS INST ALLERGY & ASTHMA RES, DAVOS, SWITZERLAND
[3] SLOTERVAART HOSP, DEPT PATHOL, AMSTERDAM, NETHERLANDS
[4] LEYENBURG HOSP, DEPT OTORHINOLARYNGOL, THE HAGUE, NETHERLANDS
[5] FREE UNIV AMSTERDAM, DEPT CELL BIOL, DIV ELECTRON MICROSCOPY, 1007 MC AMSTERDAM, NETHERLANDS