Coomb's test!

Coomb's test refers to two clinical blood tests used in  immunology. The two Coombs tests are thedirect Coomb,s test , and the indirect Coombs test .

The more commonly used test, the Direct Coombs test, is used to test for autoimmune hemolytic anemia.

In certain diseases or conditions an individual's blood may contain IgG antibodies that can specifically bind to antigens on the red blood cell surface membrane, and their circulating red blood cells can become coated with IgG alloantibodies or IgG autoantibodies. Complement proteins may subsequently bind to the bound antibodies.

 The direct Coombs test is used to detect these antibodies or complement proteins that are bound to the surface of red blood cells; a blood sample is taken and the RBCs are washed (removing the patient's own plasma) and then incubated with antihuman globulin (also known as Coomb"s reagent). If this produces agglutination of RBCs, the direct Coombs test is positive, a visual indication that antibodies  are bound to the surface of red blood cells.

The indirect Coombs test is used in prenatal testing of pregnant women, and in testing blood prior to a blood transfusion. It detects antibodies against RBCs that are present unbound in the patient's serum. In this case, serum is extracted from the blood, and the serum is incubated with RBCs of known antigenicity. If agglutination occurs, the indirect Coombs test is positive.