Myeloid depletion in the bone marrow of cynomolgus monkeys receiving 0.2 mg/kg CLL1-CD3L. Myeloid cell number, assessed by either CD11b reactivity (A) or CLL-1 reactivity (B), were markedly attenuated on day 8 (nadir of peripheral neutrophils) compared with day 22 (peripheral neutrophil recovery). Horizontal and vertical lines represent mean and standard deviation, respectively. (C) Bone marrow histology at day 8 revealed marked depletion of late-stage myeloid cells with a relative increase in early myeloid progenitors (arrows), suggesting that hematopoietic stem cells were not affected at this dose. (D) By day 22, late-stage myeloid cells were recovered and minimally increased in relative abundance (asterisks). Images of FFPE 5-µm sections stained with hematoxylin and eosin were acquired on an Olympus BX53 (Olympus, Burlingame, CA) camera, objective UPlanSApo 40x/0.95 at 20-23°C, and photographed with an Infinity 2 camera and analyzed with Infinity Analyze software (Lumenera, Ottawa, Ontario, Canada).