Increased sensitivity of the indirect antiglobulin test is achieved by using which one of the following?

• A. Albumin
• B. Saline
• C. Glucose
• D. Heparin

Answer: (A)

In the indirect antiglobulin test, increasing sensitivity means making it easier for antibodies in serum to bind to red cell antigens during incubation so that the subsequent antiglobulin reagent can reveal those bindings. Albumin serves as an enhancement medium because it helps overcome repulsion between the negatively charged red cell surfaces and the antibodies. By providing a protein-rich environment, albumin brings red cells and IgG antibodies closer together and facilitates the bridging of antibodies between cells, leading to more complete sensitization during incubation. When the anti-human globulin reagent is added, these sensitized cells give a stronger, more readily detectable agglutination, allowing weaker antibodies to be detected. Saline does not promote this sensitization, and glucose or heparin are not used for increasing IAT sensitivity in this context.