Which description correctly defines an immunochromatographic assay?

Which description correctly defines an immunochromatographic assay?

• A. An immune test in which antigen molecules form visible immune complexes with antibodies labeled with a colored substance
• B. A rapid DNA-based test
• C. A chemical colorimetric pH indicator test
• D. A test that measures antibody binding to antigens using radioactivity

Answer: (D)

Immunochromatographic assays are rapid, lateral flow tests that use an antibody labeled with a colored particle. When the sample contains the target antigen, it binds to the labeled antibody to form an immune complex that migrates along a porous strip by capillary action. This complex is captured at a test line by another immobilized antibody, producing a visible colored line. The signal comes from the colored label, not from radioactivity, and the test is not DNA-based or pH-indicator based. So the best description is an immune test in which antigen molecules form visible immune complexes with antibodies labeled with a colored substance.

Immunochromatographic assays are rapid, lateral flow tests that use an antibody labeled with a colored particle. When the sample contains the target antigen, it binds to the labeled antibody to form an immune complex that migrates along a porous strip by capillary action. This complex is captured at a test line by another immobilized antibody, producing a visible colored line. The signal comes from the colored label, not from radioactivity, and the test is not DNA-based or pH-indicator based. So the best description is an immune test in which antigen molecules form visible immune complexes with antibodies labeled with a colored substance.