(A–C) Blood leukocytes after ex vivo treatment with 10 μg/mL isotype (gray) or NC525 (red) with (A) or without (B) exogenous collagen or CD45^loSSC^lo blasts with collagen (C). n = 3 technical replicates. (D) Percentage dead leukocytes or blasts treated as in A and B relative to LAIR-1 surface expression. Each dot represents an individual patient. Red or blue shading indicates LAIR-1 greater or less than 20,000 arbitrary units, respectively. Line represents linear regression. (E) Total live cells or blasts from healthy or AML donors after treatment as indicated in A and B. n = 4–7 donors. (F) AlphaLISA of phosphorylated SHP-1 relative to total SHP-1 in AML PBMCs, normalized to isotype treatment. n = 3 technical replicates. (G and H) Duplicate dot blots from phospho-arrays of AML PBMCs quantified for MAPK (G) or mTOR and NF-κB activity (H). (I) Schematic of LAIR-1 (blue) clustering using anti-IgG (green) and NC525 (red). In vitro growth of MV4-11-LAIR-1^{overexpressing} cells treated with isotype (gray) or NC525 (red) in the absence or presence of anti-IgG. (J) Annexin V staining of cells treated as in I, with representative scatterplot of apoptotic annexin V⁺ Live-Dead Aqua^– cells at day 3 of culture. (K and L) 4E-BP1 expression as measured by Lumit assay (K) or cleaved caspase-7 as measured by Western blot (L) of cells treated as shown in I. Mean pixel density normalized to histone-3 for triplicate samples. (M) Percentage TUNEL⁺ MV4-11-LAIR-1^{overexpressing} cells at day 3 of treatment plus DMSO vehicle, 50 μM 220509-74-0 (caspase-3/7 inhibitor), or 50 μM MHY1485 (mTOR activator). Values normalized to isotype for each respective condition. n = 3–4 technical replicates. P values calculated by Student’s t test. Error bars represent SEM.