Antiglobulin/Coombs Test
Introduction · IgG/IgM antibodies occasionally coat red blood cells (RBCs) without causing agglutination due to their monomeric structure. · The small size of antibody molecules prevents cross-linked bridges formation. · Coombs, Mourant, and Race developed a test in 1945 to detect these non-agglutinating, coating antibodies. Principle · RBCs coated with incomplete antibody (IgG) or C3 complement do not cause agglutination. · Coombs reagent contains antibodies against human IgG/IgM/complement. · Anti-Human Globulin (AHG) reacts with human globulin molecules, either bound to RBCs or free in serum. FDA Licensed Antihuman Globulin Reagents - Polyspecific 1. Rabbit polyclonal: Contains anti-IgG and anti-C3d. 2. Rabbit/murine monoclonal blend. - Monospecific 1. Anti-IgG (Rabbit polyclonal): Contains anti-IgG with no anticomplement activity. 2. Anti-IgG (Gamma-done AHG): Murine monoclonal