Antibodies that specifically bind to CD38, as well as constructs comprising such antibodies fused to attenuated interferon alpha-2B proteins are provided. Anti-CD38-attenuated interferon alpha-2b fusion constructs may be used to inhibit proliferation in cancerous cells that express both CD38 and the receptor for IFN-alpha2b, as well as to induce apoptosis in such cells. Inhibition of proliferation and induction of apoptosis in cancerous cells may serve as the basis for the treatment of the underlying cancer.