Solid-phase bead assays may be supplied as pooled antigen panels, single-patient phenotypes, or single antigen beads. Pooled panel beads with many different class I or II HLA antigens on a bead yield a positive/negative result and are used for screening. Phenotype (also called ID) beads are each coated with class I or II HLA antigens of an individual patient derived cell line and estimate panel-reactive antibody by the percentage of positive beads. Single antigen beads are each coated with a single HLA antigen and yields a list of discrete antibody specifities. Specifities are then compared with HLA frequencies in the donor population to determine the calculated panel-reactive antibody, which is presently the best estimate of likeli-hood of a positive crossmatch assays/donor-specific HLA antigen to a randomly selected donor. Single antigen beads results further enable virtual crossmatching to identify donor-specific antigen pretransplant, in turn fascilitating allocation and risk assessment. Virtual crossmatching has also been used without cell-based crossmatch in some transplant circumstances where legislation permits, or under study conditions, with acceptable (equivalent rejection rates and graft survival at a population level) results. Additional enhancements of the single antigen beads assay, such as detecting antibodies capable of binding complement component C1q, have been developed to detect potentially more injurious antibodies.