Step 1. Lateral flow test strips commonly consist of a sample pad, a conjugate pad that has been impregnated with conjugated antibodies, for example, gold conjugated Goat Anti-Human Fcγ specific antibodies and two “lines” which have been applied to nitrocellulose with antigen (T), and control antibodies, for example, Bovine Anti-Goat (C).
Step 2. The sample is introduced to the sample pad via a hole in the test strip cassette.
Step 3. Capillary action draws the sample into the conjugate pad and rehydrates the impregnated antibody conjugates. Any antibodies in the sample to which the conjugated antibody is specific will form complexes.
Step 4. The sample and complexed antibodies migrate onto the antigen-coated nitrocellulose (T) test “line” where they interact.
Step 5. If the antibodies in the sample are specific to the coated antigen the antibody complexes will be deposited and develop color over the line giving a visual indication of a “positive” test. If there are no antibodies specific to the antigen in the test sample, no colored line will develop. Un-complexed gold conjugated Goat Anti-Human antibodies continue to migrate through the test strip to the control line (C).
Step 6. The free conjugated Goat Anti-Human antibodies can be captured by the coated Bovine Anti-Goat IgG and develop a colored line to indicate the test has been performed correctly. No control line would indicate an invalid test.
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