COMPLICATIONS IN THE FUNCTIONAL-ANALYSIS OF TRANSFECTED MHC GENES

Analysis of the relationship between the structure of a protein molecu le and its function often exploits the techniques of gene mutation and expression in transfected cell lines. This approach has been used ext ensively in the study of MHC molecules for testing predictions derived from structural models. Comparison of the functional properties of mu tant molecules is difficult because MHC molecules interact with both p eptides and T cell receptors. Functionality is commonly determined in biological assays which are dependent on T cell recognition of specifi c peptide/MHC complexes and measure secondary events triggered by T ce ll activation. In this study four L cell lines transfected with differ ent combinations of alpha and beta chains from I-A(k) and I-A(u) were used as antigen-presenting cells to activate two hen egg-white lysozym e-specific T cell clones. We compared several biological assays, namel y, T cell proliferation, cytokine production, and cytotoxicity. Differ ent assays indicated varying degrees of functionality for the same MHC molecule and thus demonstrated the difficulty in unambiguous interpre tation of data from complex assays. Furthermore, we detected differenc es among the transfected lines which appeared unrelated to the express ion of the introduced MHC genes. (C) 1994 Academic Press, Inc.