Quantitation of Component Molecules of Precipitated Class II Complexes
The use of a scanning instrument that detects β emissions from dried gels has enabled us to quantitate emission levels from individual class II products. If radiolabeled molecules are presented as discrete spots or bands on an SDS/PAGE gel, they can be detected and analyzed. The instrument used is an AMBIS Mark II β scanner (Automated Microbiology Systems, Inc.), which detects β particles passed through a mylar filter into an argon-methane mix. Localization of each ionization event is determined, and a two-dimensional representation is built up. The scanner is operated from an IBM PC AT-X, which allows data to be stored and retrieved for subsequent analysis. We examined profiles from cells expressing class II products to determine whether the location of the epitope on the dimer had an effect on the ratio of α and β chains bound by monoclonal antibody. We then used this to examine the expression of α and β chains in P815-transfected cells.