Chapter 50 Human Blood Group Antigens and Antibodies
IgSF, Immunoglobulin super family; ISGN, International Society for Gene Nomenclature; type I, protein with a single pass through the RBC lipid bilayer with its amino terminus to the outside of the cell; type II, protein with a single pass through the RBC lipid bilayer with its amino terminus to the inside of the cell.
Figure 50-1 MODEL OF BLOOD GROUP PROTEINS IN THE RED BLOOD CELL (RBC) MEMBRANE.
Schematic representation of the RBC molecules that carry blood group antigens and the predicted structure. These include carbohydrates, single and multipass proteins, and GPI-linked proteins in the RBC membrane.
Indirect Antiglobulin Test and Direct Antiglobulin Test
The indirect antiglobulin test (IAT) is used to detect alloantibodies in patient sera, or RBCs coated with antibody in vitro following incubation at 37° C, for example, antibody screening and identification, antigen typing, and crossmatching with donor RBCs. After incubation, unbound antibodies are removed from the RBCs by washing with saline, and an antiglobulin reagent containing either antihuman IgG or a mixture of antihuman IgG and monoclonal antihuman complement is added. Agglutination of all cells suggests the presence of an antibody to a high-prevalence antigen or the presence of an autoantibody; differential reactivity suggests the presence of antibodies to one or more specific RBC antigens.