CD34 and acute myeloid leukemia: As noted above, except for uniformly bright CD123 (Figure 4A) and bright, mildly variable HLA-DR expression (Figure 4D), most antigens on pDCs in pDC-AML were expressed in a heterogeneous manner retaining a degree of differentiation/maturation reminiscent of normal/reactive pDCs in bone marrow; the brightest CD34+ subset corresponded to the earliest pDCs that were dim to negative for CD4 and CD303 (Figure 4F–H).