CR2 and B-cell chronic lymphocytic leukemia: Our results may also explain the lack of anti-CD19 uptake in B-cells from patients with B-cell chronic lymphocytic leukemia (B-CLL) (Sieber et al, 2003), since these are mostly CD21+ (Nadler et al, 1983; Lopez-Matas et al, 2000; Cherukuri et al, 2001a).