Using FBS-free medium, we first investigated the induction of apoptosis in PBMC from three CLL patients (Fig. 7) with 80% or more CD19+ CD5+ ROR1+ cells following incubation for three days with IgG1 R11, R12, Y31, TT11, and rituximab alone or in the presence of a cross-linking pAb. Here, ROR1 is linked to B-cell chronic lymphocytic leukemia.