CD30 is a member of the tumor necrosis factor receptor family. Overexpression of CD30 on some neoplasms versus its limited expression on normal tissues makes this receptor a promising target for antibody-based therapy. Anaplastic large-cell lymphoma (ALCL) represents a heterogeneous group of aggressive non-Hodgkin lymphomas characterized by the strong expression of CD30. We investigated the therapeutic efficacy of HeFi-1, a mouse IgG1 monoclonal antibody, which recognizes the ligand-binding site on CD30, and humanized anti-Tac antibody (daclizumab), which recognizes CD25, in a murine model of human ALCL. The ALCL model was established by intravenous injection of karpas299 cells into nonobese diabetic/severe combined immuno-deficient (SCID/NOD) wild-type or SCID/NOD Fc receptor common gamma chain-deficient (FcRgamma(-/-)) mice. HeFi-1, given at a dose of 100 microg weekly for 4 weeks, significantly prolonged survival of the ALCL-bearing SCID/NOD wild-type and SCID/NOD FcRgamma(-/-) mice (P < .01) as compared with the control groups. In vitro studies showed that HeFi-1 inhibited the proliferation of karpas299 cells, whereas daclizumab did not inhibit cell proliferation. We demonstrated that the expression of FcRgamma on polymorphonuclear leukocytes and monocytes was not required for HeFi-1-mediated tumor growth inhibition in vivo, although it was required for daclizumab.