Test Band (T Line)
Definition
The line on the lateral-flow card that appears when the anti-haemoglobin antibody captures haemoglobin-laden conjugate. Its presence constitutes a positive result.
- Assay type
- Lateral-flow immunoassay card
- Target
- Anti-haemoglobin antibody capture
- Positive result
- T line appears
- Companion line
- Control (C) line confirms assay validity
Common questions
What does it mean if only the control line appears?+
It means the test ran correctly but the sample tested negative for haemoglobin, so the stain in question is not confirmed as blood by this assay, though a negative result does not rule out heavily degraded or diluted blood.
Can a test line appear without human blood present?+
Yes, cross-reactivity with blood from some other species can occasionally produce a faint line, which is why a positive lateral-flow result is treated as a presumptive indicator and followed by a confirmatory species test where the case requires it.
Related terms
- Anti-Human Haemoglobin Antibody
- A monoclonal antibody raised against epitopes unique to human haemoglobin. Forms the detection and capture antibodies on the lateral-flow strip, conferring specificity...
- Control Band (C Line)
- A second line that captures excess labelled antibody regardless of whether the analyte is present. Its appearance confirms the assay ran correctly....
- Cross-Reactivity
- The capacity of an antibody raised against one analyte to bind structurally related compounds. In RIA, cross-reactivity is the main driver of...
- Lateral-Flow Immunochromatography
- A test format in which a liquid sample flows laterally along a membrane, encounters labelled detection antibodies, and is captured at specific...
- Prozone Effect
- A false-negative serological result caused by antibody excess. When antibody concentration is too high relative to antigen, antibodies saturate individual antigen molecules...