Schematic representation of the chimeric receptors used in this study. (A) Receptors that are inducibly dimerized after addition of a cytokine. The transmembrane (TM) segment is derived from the same cytokine receptor as the cytoplasmic domain in each case. (B) Receptors that exist as constitutive dimers by virtue of the hCD8 extracellular domain, which forms a disulfide-linked dimer. The transmembrane portion is derived from the same cytokine receptor as the cytoplasmic domain in each case. (C) Receptors that are inducibly dimerized after addition of an antibody against CD16. The transmembrane portion is derived from CD7.