Flow cytometric enumeration of residual WBCs in leukoreduced blood and measurement of T-cell chimerism in recipient mice. Each leukoreduced unit of blood was analyzed for residual WBCs. (A) A representative analysis is shown. Leukoreduction resulted in fewer than 1000 rWBCs on average. Peripheral blood from recipient and control mice was stained with antibodies against Thy1.1 and Thy1.2 and analyzed by flow cytometry after gating on CD3⁺ events. (B) Representative plots of a mouse with engraftment and a mouse displaying rejection of BMT are shown.