Here macrophages were polarized with either IFN-γ and LPS (M1) or IL-4 and IL-13 (M2), then cocultured for 1 hour with CFSE-labelled CLL cells that had been opsonized with either the anti-CD20 chimeric human IgG1 antibody, rituximab, or trastuzumab as an isotype control. The gene discussed is IL4; the disease is B-cell chronic lymphocytic leukemia.