Applications of the immunoglobulin Cw fragment (IgCw) composed of the constant regions of heavy and light (CH and CL) chains

Abstract

We report the production and application of a recombinant IgCw molecule, which is composed of only the constant domains of the heavy (CH) and light (CL) chains, lacking a variable (V) domain. We produced IgCw, especially human IgCw-gammakappa (98kDa), composed of two human Cgamma chains (37kDa each) and two Ckappa chains (12kDa each), using HEK293F cell culture. We found that the yield of IgCw-gammakappa protein was approximately 20mg/L, which was comparable to that of full-size IgG: it bound to Fcgamma receptor-positive cells with a low background noise on Fcgamma receptor-negative cells: and IgCw-gammakappa can be used as a reference for measurement of Ig concentration. Moreover, Cgamma and Ckappa chains were easily isolated from IgCw-gammakappa by a single step of affinity chromatography in the presence of a reducing agent. These results demonstrate that the IgCw molecule has the potential to be used for certain in vitro and in vivo applications as an alternative to an irrelevant isotype control IgG, and to be used a favorable antigen for acquiring isotype-specific antibodies by immunizing animals.