Monoclonal antibodies and fusion proteins in medicine. 
Humanized antibodies and decoy receptors have been introduced in clinical practice to treat malignancies and systemic autoimmune disease because they ablate specific cells or disrupt pathogenic processes at distinct points.  Reported clinical responses offer hope to treatment-resistant patients, particularly those with lymphomas and rheumatic diseases.  Side effects from the use of biologic agents include lymphokine release syndrome, reactivation of tuberculosis, and immunosuppression.  Further insights are needed regarding limitation of adverse effects, correct use in conjunction with existing drugs, and treatment of patients in whom resistance develops.