HIGH-AFFINITY IMMUNOGLOBULIN-E RECEPTOR (FC-EPSILON-RI)-BEARING EOSINOPHILS, MAST-CELLS, MACROPHAGES AND LANGERHANS CELLS IN ALLERGEN-INDUCED LATE-PHASE CUTANEOUS REACTIONS IN ATOPIC SUBJECTS

We have used in situ hybridization (ISH) and immunohistochemistry (IHC ) to investigate the kinetics of the expression for Fc epsilon RI mRNA (alpha-, beta- and gamma-chains), the alpha-chain protein product, as well as the phenotype of the mRNA- or protein-positive cells in aller gen-induced late-phase skin reactions in atopic subjects. Compared wit h diluent controls, there were significant increases in the total numb ers of mRNA(+) cells for the alpha-, beta- and gamma-chains for Fc eps ilon RI at all time-points (6, 24 and 48 hr) after allergen challenge (P < 0.01). By double IHC/ISH significant increases in alpha-, beta- a nd gamma-chain mRNA(+) macrophages, eosinophils, mast cells and CD1a() cells were also observed after allergen challenge (P < 0.05). The di stribution of Fc epsilon RI subunit (alpha-, beta-, or gamma-chain) mR NA(+) co-localization was CD68(+) macrophages (42-47%), EG2(+) eosinop hils (33-39%), tryptase(+) mast cells (5-11%) and CD1a(+) Langerhans' cells (2-4%). Using single IHC, significant increases in the total num ber of Fc epsilon RI protein(+) cells (P < 0.01) were observed 24 and 48 hr after allergen challenge. Double IHC showed that the distributio n of Fc epsilon RI+ cells was tryptase(+) mast cells (33%), CD68(+) ma crophages (36%), EG2(+) eosinophils (20%), CD1a(+) Langerhans' cells ( 4%) and unidentified cells (7%), at the 24-hr allergen-challenged site s. These observations suggest that the cutaneous late-phase reaction i n man is associated with up-regulation of Fc epsilon RI on eosinophils , macrophages, mast cells and Langerhans' cells.