Immunohistological specification of the immunosuppression-inducing IDO-1 in SPTL. a) Double IHC staining of CD8 (cyan) and IDO-1 (red) shows that IDO-1 is mostly expressed in other cells than CD8+ lymphocytes in a SPTL lesion (20x). b) Here, double staining of CD8 (cyan) and CXCR3 (red) shows the expressions in same cells in SPTL as comparison (red arrow, 40x). c) Double staining of IDO-1 (red, red arrow) and the macrophage marker CD68 (cyan, blue arrow) shows expression mainly in different cells (40x). d)-e) Perinodular fat, infiltrated with morphologically malignant lymphocytes, surrounding an enlarged lymph node of a SPTL patient (case 4, Table 1). Similar d) IDO-1 and e) CXCR3 expression is seen as in subcutaneous SPTL lesions. f)-h) Double IF staining of CD11c (red) and IDO-1 (green) confirms that IDO-1 is not expressed by CD11c -positive dendritic cells (Leica confocal microscopy, 40x).