title: Eosinophil granulocytes account for indoleamine 2,3-dioxygenase-mediated immune escape in human non-small cell lung cancer.
abstract: Indoleamine 2,3-dioxygenase (IDO), a catabolizing enzyme of tryptophan, is supposed to play a role in tumor immune escape. Its expression in solid tumors has not yet been well elucidated: IDO can be expressed by the tumor cells themselves, or by ill-defined infiltrating cells, possibly depending on tumor type. We have investigated IDO expression in 25 cases of non-small cell lung cancer (NSCLC). Using histochemistry and immunohistochemistry, we found that IDO was expressed not by tumor cells, but by normal cells infiltrating the peritumoral stroma. These cells were neither macrophages nor dendritic cells, and were identified as eosinophil granulocytes. The amount of IDO-positive eosinophils varied in different cases, ranging from a few cells to more than 50 per field at x200 magnification. IDO protein in NSCLC was enzymatically active. Therefore, at least in NSCLC cases displaying a large amount of these cells in the inflammatory infiltrate, IDO-positive eosinophils could exert an effective immunosuppressive action. On analyzing the 17 patients with adequate follow-up, a significant relationship was found between the amount of IDO-positive infiltrate and overall survival. This finding suggests that the degree of IDO-positive infiltrate could be a prognostic marker in NSCLC.
authors.affiliation: Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy.
authors.forename: Simonetta
authors.initials: S
authors.lastname: Astigiano
authors.forename: Barbara
authors.initials: B
authors.lastname: Morandi
authors.forename: Roberta
authors.initials: R
authors.lastname: Costa
authors.forename: Luca
authors.initials: L
authors.lastname: Mastracci
authors.forename: Antonella
authors.initials: A
authors.lastname: D'Agostino
authors.forename: Giovanni Battista
authors.initials: GB
authors.lastname: Ratto
authors.forename: Giovanni
authors.initials: G
authors.lastname: Melioli
authors.forename: Guido
authors.initials: G
authors.lastname: Frumento
mesh_terms: D000328:Adult; D000368:Aged; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism; D004804:Eosinophils / Q000166:cytology*; D005260:Female; D006098:Granulocytes / Q000166:cytology*; D006801:Humans; D007107:Immune System; D007150:Immunohistochemistry; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D007249:Inflammation; D008175:Lung Neoplasms / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011379:Prognosis; D014366:Tryptophan Oxygenase / Q000378:metabolism*
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D014366:Tryptophan Oxygenase