Immunocytochemical determination of p16(INK4A) expression in sorted bone marrow stem cells.

Adult ALL bone marrow was sorted as described in “Materials and methods.” Sorted stem cells (CD34+lin−) were collected on slides and stained for p16(INK4A) expression. The slide images were captured using an inverted microscope at 125× magnification. The images were transferred to a computer using a frame grabber board (Target+; Truevision) and stored in computer files using Java image analysis software (Jandel Scientific, Corte Madona, CA). Left panel: sorted CD34+lin− cells from a p16(INK4A)-positive ALL bone marrow. Note positive nuclear localization. Right panel: sorted CD34+lin− cells from a p16(INK4A)-negative ALL bone marrow. Nuclei are unstained.