Immunoperoxidase staining of of freshly isolated and cultured CML cells with anti-CD1a antibody. Freshly isolated (A) or 10-day cultured, nonadherent CML cells (B) were adhered to poly-l-lysine–coated coverslips and stained with anti-CD1a and peroxidase-conjugated antimouse IgG. Cells stained with isotype control antibody and peroxidase conjugate were similar to those depicted in (A) (data not shown).