Why must IgG-coated check cells be added to all negative antihuman globulin tests?
1To confirm that the patient sample truly contained no unexpected antibody
2To confirm that active antiglobulin reagent was present and was not neutralized✓ 정답
3To confirm that the centrifuge speed and timing were set correctly
4To detect complement-dependent antibodies that are missed at the antiglobulin phase
해설
Incomplete washing leaves residual serum globulins that neutralize the antihuman globulin reagent and produce a false negative. Adding IgG-sensitized cells verifies that the reagent was still active: agglutination confirms validity, and no agglutination invalidates the negative result, which must then be repeated.