Vaccine site biopsy reveals a mixed inflammatory infiltrate. Representative photomicrograph of a skin punch biopsy obtained from a patient in Cohort A, 2 days after receiving the first dose of Melanoma GVAX. H&E staining reveals a dense, mixed inflammatory infiltrate centered primarily in the superficial subcutaneous adipose tissue (blue inset box), including lymphocytes, histiocytes, eosinophils, and irradiated melanoma vaccine cells. Left image, ×10 original magnification; right image, ×200 original magnification. Black arrowhead, dermal/subcutaneous junction; black arrows, Melanoma GVAX cells; green arrows, eosinophils. Immunohistochemical characterization is shown in Additional file 3: Figure S2.