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Correct Answer: indirect antiglobulin test (iat)
the correct answer to the question is the indirect antiglobulin test (iat). here's an expanded explanation of the process:
the indirect antiglobulin test (iat), also known as the indirect coombs test, is a diagnostic laboratory procedure used primarily in immunohematology to detect antibodies against red blood cells (rbcs) that are present unbound in the patient's serum. this test is crucial in pre-transfusion testing, detecting hemolytic disease of the newborn, and in autoimmune hemolytic anemia.
the iat involves several steps to ensure the accurate detection of antibodies. initially, the patient's serum is collected. serum is the liquid component of blood without cells and clotting factors, containing antibodies if the immune system has been stimulated by antigens on foreign rbcs. then, the laboratory technician mixes the patient's serum with commercially prepared rbcs that possess known antigenic profiles. this mixture is incubated at body temperature, typically 37 degrees celsius, which is the normal human body temperature. this step is crucial as it allows any igg antibodies present in the serum ample time to bind to their corresponding antigens on the rbcs if they are present.
following incubation, the rbcs are washed several times with saline. this washing process removes unbound proteins and antibodies, reducing the chance of non-specific binding that might lead to false-positive results. after washing, a reagent known as anti-human globulin (ahg) is added. the ahg reagent contains antibodies against human igg and complement proteins; it will bind to any human igg or complement that has attached to the rbcs during incubation.
if the ahg reagent binds to any antibodies on the rbcs, this indicates that the patient's serum contained antibodies that recognize antigens on the rbcs, forming complexes. this reaction is typically visualized by agglutination (clumping) of rbcs, which can be observed directly or with the aid of centrifugation and microscopy techniques.
in summary, the iat is a sensitive method used to detect "in vitro" sensitization of rbcs by igg antibodies in the patient's serum. its accuracy and reliability make it a staple in transfusion medicine, ensuring transfusion compatibility and the safety of blood transfusions.
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