Abstract

Chimeric receptors that redirect effector cell function to tumor cells or virus-infected cells have received much attention. Given the high affinity of Fc(epsilon)RI for immunoglobulin E (IgE) and low serum IgE levels, redirection of effector cells using Fc(epsilon) receptor may provide a novel, versatile, and effective anti-tumor strategy. We have used a mouse perforin 5'-promoter to express a single-chain human Fc(epsilon) receptor in the mouse cytotoxic T lymphocyte cell line, CTLL-R8. Upon ligation of the chimeric Fc(epsilon) receptors by IgE, a signal for effector function is transmitted via the intracellular domain of CD3zeta. Selection in G418-containing medium produced CTLLR8 transfectant clones that: (1) expressed chimeric Fc(epsilon) receptor as determined by flow cytometry; (2) bound human IgE antibodies with high affinity as determined by Scatchard analysis; (3) specifically rosetted IgE-coated SRBC; (4) lysed target cells in IgE-mediated ADCC and reverse ADCC assays; and (5) retarded tumor growth in a Winn assay. Therefore these chimeric Fc(epsilon) receptors can effectively redirect cytotoxicity to tumor cells. Future efforts will assess the versatility and efficacy of these IgE-binding chimeric receptors to redirect killer cell function in animal tumor models.