Confocal immunofluorescence analysis of human cancer sections confirms the presence of TIE2⁺CD45⁺CD14⁺ tumor-infiltrating monocytes. (A) Colon adenocarcinoma analyzed for CD31 (green), TIE2 (red), and CD45 (blue). Confocal planes are shown individually and after merging. Several TIE2⁺CD45⁺CD31⁻ hematopoietic cells (merge of red and blue giving purple; arrows) are found within the tumor stroma. Note that TIE2 is expressed by vascular ECs (merge of green and red giving yellow; arrowheads), which are TIE2⁺CD45⁻CD31⁺. (B) Gastric adenocarcinoma analyzed for CD31 (green), TIE2 (red), and CD45 (blue). Some TIE2⁺CD45⁺CD31⁻ hematopoietic cells are found in the tumor stroma (arrows) together with TIE2⁺CD45⁻CD31⁺ tumor blood vessels (arrowhead). Scale bars as indicated. (C) Colon adenocarcinoma analyzed for CD14 (green), TIE2 (red), and CD11b (blue). Several TIE2⁺CD14⁺CD11b⁺ monocytes (arrows) are found within the tumor stroma. Note TIE2 expression by TIE2⁺CD14⁻CD11b⁻ vascular ECs (arrowheads). (D) Gastric adenocarcinoma analyzed for VWF (green), TIE2 (red), and CD11b (blue). Arrowheads indicate TIE2⁺CD11b⁺VWF⁻ monocytes. (E) Pancreatic adenocarcinoma analyzed for CD16 (green), TIE2 (red), and CD14 (blue). High-magnification photos show the presence of TIE2⁺CD16⁺CD14⁺ monocytes (arrows) in the tumor stroma. (F) Colon adenocarcinoma analyzed for CD14 (green), TIE2 (red), and CD11b (blue). A triple-positive CD14⁺TIE2⁺CD11b⁺ TEM with peri-endothelial localization is indicated by the arrow. Note the presence of CD14⁻TIE2⁻CD11b⁺ inflammatory cells (arrowheads). Scale bars as indicated. (G) TIE2 expression in nonneoplastic tissues is restricted to vascular ECs. Nonneoplastic colon mucosa adjacent to tumor tissue analyzed by confocal immunofluorescence staining of CD31 or CD14 (green), TIE2 (red), and CD45 (blue). Note that the lamina propria macrophages are CD14⁻TIE2⁻. A single CD14⁺TIE2⁻ monocyte (arrow) is found within a TIE2⁺ blood vessel. Tonsil sections show that TIE2 expression (red) is restricted to CD31⁺ vascular ECs (green). CD19⁺ B cells are stained in blue. Scale bars as indicated.