as well as detection of other cell membrane antigens or quantitation of particular cell membrane antigens application_number US 89191104 A description in one embodiment each member of a set of encoded microparticles or beads presents hla antigens derived from cells representative of the hla antigens from a single human individual such cells may be lymphocytes platelets or another cell population which presents hla antigens a preferred source is a single lymphocyte cell line or cells expressing recombinant antigens encoded by transfected hla dnas preferably the hla panel is composed so as to represent the distribution of class i and or class ii hla antigens in a normal human population and may also include most rare antigens for example native recombinant proteins while the use of antigens from a large number of cell lines renders the panel more closely representative of the natural distribution of antigens this desirable characteristic of such an assay design must be balanced against its rapidly increasing complexity which may reduce specificity and sensitivity membrane fragments containing cell surface antigens can be affixed to encoded beads using either the method of example i or another suitable method see e g wilson et al u201c a new microsphere based immunofluorescence assay for antibodies to membrane associated antigens u201d j immunol methods 107 231 237 1988 preferably such fragments are oriented such that the exterior surface faces.