A SEMIQUANTITATIVE RESETTING ASSAY FOR DETECTION OF CELL-SURFACE CLASS-I MAJOR HISTOCOMPATIBILITY COMPLEX-MOLECULES

A method for detection of cell-surface antigens, referred to as cell-b end immuno-assay (CBIA), has been developed by cross-linking monoclona l antibodies specific for cell-surface antigens to protein G-agarose b eads. In this case, the antibodies were specific for different murine class I major histocompatibility complex (MHC) antigens and murine bet a 2 microglobulin. The antibody-conjugated beads were incubated with c ells expressing the relevant MHC molecule and observed microscopically for rosette formation. The number of cells bound per bead correlated with the amount of class I MHC expressed per cell, as measured by fluo rescence activated cell sorting (FACS) analysis. In addition, changes in the amount of surface antigen expressed after induction could be fo llowed by CBIA. The advantages of CBIA over other commonly used techni ques, such as FACS and immunofluorescence, are that it requires only a few minutes incubation after bends are prepared, and no further manip ulations are needed after the cells and bends are mixed together. Alth ough CBIA is primarily a qualitative technique, it can also be used se miquantitatively by determining the number of cells bound per bead.