huHCA expression by subsets of CD34⁺ ABM cells. ABM was stained as described with MoAbs against CD34, Thy-1, rat KG-CAM (11-59; A), huHCA (F84.1; B), and isotype controls. FACS analyses of gated CD34⁺ populations are shown. MoAb 11-59 does not recognize human BM cells (A), whereas MoAb F84.1 binds a subset of CD34⁺ cells. Virtually all CD34⁺ Thy-1⁺ cells express huHCA (B). Alternatively, ABM cells were stained as described with MoAbs against CD34, huHCA, and, simultaneously, CD38 (C), CD10 (D), CD19 (E), and CD33 (F ). FACS analyses of gated CD34⁺ populations are shown. See text for details.