This invention provides chimeric proteins comprising an apoptosis-inducing molecule fused to a member of a binding pair that is capable of binding to a selected cell that expresses a death receptor. When the selected cell is exposed in vivo or ex vivo to the chimeric protein, the selected cell undergoes apoptosis. The preferred embodiment is FasL protein fused to streptavidin. The methods of using the chimeric proteins are especially beneficial in causing activated lymphocytes to undergo apoptosis, thus modulating the immune response. Patients with conditions such as asthma or allergy, or patients undergoing transplantation with allogeneic or xenogeneic tissue are examples of patients who benefit from the methods of this invention.