Immunoprecipitation analysis of FcγRIIIb from a SH(+), NA1(+),NA2(+) individual using biotin-labeled granulocytes. After granulocytes were biotin-labeled and lysed, the FcγRIIIb was precipitated with a serum containing an isoantibody to FcγRIIIb (lane 1), a negative control serum (lane 2), and the SH-specific serum (lane 3). Immunoprecipitates were analyzed by 10% SDS-PAGE under nonreducing conditions, transferred onto nitrocellulose, and visualized using streptavidin-horseradish peroxidase and chemiluminescence substrate.