title: The defined antigen substrate spheres (DASS) system and some of its applications.
abstract: A quantitative immunofluorescent technique based on the covalent coupling of protein to Sepharose beads, the so-called defined antigen substrate spheres (DASS) system is described, and the main technical aspects are discussed. The method proved to be reproducible and has a lower detection limit equivalent to the amount of antigen, present per bead, that can bind 1 pg fluorescent labeled antibody. The DASS system has many applications, and some of them are discussed, such as the quantitation of antibodies and antigens with Sepharose-coupled antigens or antibodies. Not only antigen-antibody interactions but also any reaction that results in a stable complex can be studied, provided antisera against one of the constituents are available. An example is given by the complement fixation to Sepharose-coupled IgG. For the quantitation of hydrophobic antigens, hydrophobic Sepharise can be used.
mesh_terms: D000906:Antibodies / Q000032:analysis; D000941:Antigens / Q000032:analysis; D003165:Complement System Proteins; D003488:Cyanogen Bromide; D004983:Ethanolamines; D005455:Fluorescent Antibody Technique / Q000592:standards*; D006863:Hydrogen-Ion Concentration; D007136:Immunoglobulins / Q000592:standards*; D008854:Microscopy, Electron; D008970:Molecular Weight; D011108:Polymers; D011134:Polysaccharides / Q000592:standards*; D012685:Sepharose / Q000592:standards*; D012995:Solubility; D012997:Solvents
chemical_list: D000906:Antibodies; D000941:Antigens; D004983:Ethanolamines; D007136:Immunoglobulins; D011108:Polymers; D011134:Polysaccharides; D012997:Solvents; D003165:Complement System Proteins; D012685:Sepharose; D003488:Cyanogen Bromide