Production and secretion of recombinant soluble CD3 polypeptides by myeloma-derived transfectant clones

Soluble forms of three human CD3 proteins have been produced by recombinant DNA techniques. The extracellular domain of CD3-gamma, -delta or -epsilon has been linked to the constant region of mouse immunoglobulin kappa light chain to form gamma-kappa, delta-kappa and epsilon-kappa chimaeric proteins. These are secreted by mouse myeloma-derived transfectant cell lines and are immunoprecipitable by CD3- or kappa-specific polyclonal antisera. Yields of 100-500 micrograms secreted recombinant proteins per litre of culture medium were obtained, which could be purified by anti-kappa affinity chromatography. The production of soluble CD3 illustrates the applicability of this technology to a loosely associated protein complex.