Coombs test

The Coombs test is an agglutination test used in biochemistry to detect proteins, specifically antibodies, on the surface of red blood cells. This test is crucial for identifying blood groups and understanding certain medical conditions.12

How it Works

When incomplete antibodies attach to red blood cells, they coat the cells with a substance called gamma globulin, but this doesn't cause visible clumping (agglutination) in a saline solution. The Coombs test detects this gamma globulin. It involves adding Coombs serum (antihuman globulin) to washed red blood cells. If gamma globulin or complement is present on the cells, agglutination will occur, indicating a positive result.2

Applications

The test can identify incomplete antibodies in serum or antibodies bound to the red blood cell membrane. It is used in cases of autoimmune hemolytic anemia, where a person produces antibodies against their own red blood cells, or in hemolytic disease of the newborn, where a mother produces antibodies against her baby's red blood cells.2