Induction of tumor-lysate-specific DTH after DC vaccination. (A) Positive DTH reaction (25 mm) in patient 1 after intradermal injection of tumor lysate. Immunohistochemical investigations were performed using mAbs for CD4 (B), CD8 (C), and TIA (D). Note heavy infiltration of DTH challenge site. Sections were stained using the APAAP technique and counterstained with hematoxylin. Original magnification, × 200 (B-D).