T-ALL engraftment in NS122 recipients. (A) NS122 mice were injected intrafemorally with 1 × 10³ to 1 × 10⁷ T-ALL cells from 9 patient samples. Xenografts were assessed 20 weeks after injection by flow cytometry for the percentage of human CD45⁺CD7⁺CD5⁺ cells in the BM with each symbol representing one recipient. The bar represents the mean percentage for each T-ALL sample. (B) Spleens from engrafted NS122 xenografts were weighed. Graph depicts spleen weight (y-axis) with percentage of human CD45⁺CD7⁺CD5⁺ leukemia cells in the BM (x-axis) from engrafted recipients, with each dot representing one recipient. Linear regression analysis revealed correlation between level of RF engraftment and spleen weight (P = .0058). (C) BM cells from engrafted NS122 xenografts injected with 1 × 10⁴ (left panel), 1 × 10⁵ (middle panel), or 1 × 10⁶ (right panel) 5178 T-ALL cells were analyzed by flow cytometry. The figure represents results gated on human CD45⁺ cells that coexpress CD1a and CD5. (D) The percentages of CD45⁺ T-ALL cells coexpressing surface CD5, CD1a, and CD38 from NS122 recipients injected with 1 × 10⁴ to 1 × 10⁶ 5178 T-ALL cells are shown, with each dot representing one NS122 recipient.