Studies have demonstrated the role of CD4 T cells in allergic and autoimmune disease, but the search for a means to selectively target and eliminate the cells responsible has proved difficult. On page 142, Casares et al. describe a method for delivering drugs to antigen-specific T cells. They engineered a construct to target and destroy specific T cells by attaching the drug doxorubicin to recombinant MHC class II–peptide chimeras on an immunoglobulin scaffold. They demonstrated that the construct could bind to and deliver the drug to T cells that specifically recognized the peptide–MHC complex, thereby killing the cells. Delivery of the construct in transgenic mice reduced the frequency and proliferation of T cells specific for the peptide–MHC complex. The work has potential application for drug delivery to specific pathogenic T cells.