Human Blood Group Antigens and Antibodies

Chapter 50 Human Blood Group Antigens and Antibodies

Connie M. Westhoff, Jill R. Storry, Beth H. Shaz

Table 50-1 Blood Group Systems, Antigens, Expression, and Disease Associations

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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.

Table 50-2 Uses of DNA-Based Genotyping Assays for Transfusion Medicine

Type patients who have been recently transfused

Type RBCs coated with immunoglobulin

Type patients with AIHA (to select antigen-negative RBCs for transfusion and absorption of autoantibodies when searching for under-lying alloantibodies)

Type RBCs when commercial antisera are not available

Type for numerous blood group antigens in a single assay

Identify weak D and partial D (to determine candidate for Rh immune globulin or avoid use of limited Rh-negative donor supply)

Resolve blood group typing discrepancies

Determine paternal zygosity for RHD and HPA

Type fetus to determine risk for HDFN or NAIT

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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.

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Jun 12, 2016 | Posted by in HEMATOLOGY | Comments Off on Human Blood Group Antigens and Antibodies

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