Establishment of xenografts. NOD/SCID mice were irradiated with 275 cGY and were injected with 107 lymphoblasts obtained from patients with pre-B ALL. Xenografts were established from 78% of patient samples used as assessed by flow cytometry for ALL. Top panel shows flow cytometric analysis of CD45 and CD19 staining of peripheral blood from a control mouse (A, 0.1%) and a xenografted mouse (D, 32%). Splenocytes from this mouse were 65% human ALL (B), and bone marrow was 94% human ALL (C). The majority of xenografted animals had more than 90% replacement of bone marrow and more than 60% replacement of spleen with human ALL. Also pictured are photomicrographs of Wright-Giemsa-stained peripheral blood (E) with human lymphoblast (arrow) and murine granulocyte (shown) and a cytospin prepared from bone marrow nucleated cells showing a monomorphic population of lymphoblasts (F). Images were captured using a Zeiss Axiovert 40C light microscope (Carl Zeiss, Thornwood, NJ) equipped with an apochromatic 40 ×/0.60 NA objective lens and a Nikon 995 camera (Nikon, Melville, NY).
