Characterization of the TIE2⁺ monocytes. (A) TIE2⁺ cells in unfractioned PBMCs were gated and analyzed for the expression of a panel of hematopoietic markers, as indicated in the histogram plots. The red open line shows expression of the indicated marker in the gated TIE2⁺ population (with the percentage of marker-positive cells in red); the filled line depicts expression of the indicated marker in the TIE2⁻ cell population (with the percentage of marker-positive cells in black). The TIE2⁺ cells were CD45⁺, CD11b⁺, CD11c⁺, CD16⁺, CD33⁺, CD115⁺, and CD13⁺, which are all markers of monocytic cells. In addition, the TIE2⁺ cells were CCR2⁻, CD62L (L-selectin)⁻, and CCR5⁺, a surface profile previously associated with resident monocytes. As expected, the TIE2⁺ cells were CD56⁻, CD3⁻, and CD19⁻ and thus distinct from natural killer cells and T and B lymphocytes. Representative analysis of 3 to 6 experiments performed on different donors.