Qualification in Immunohistochemistry (QIHC) Practice Exam

Fluorescent tyramide amplification boosts the detected signal by using horseradish peroxidase to catalyze the covalent deposition of many fluorescent tyramide molecules at the antigen site. Each HRP event can generate a cluster of labeled molecules right where the target is, so a single antigen can produce a much stronger, localized fluorescence signal. In typical assays, this amplification yields roughly a fifty-fold increase in sensitivity, with some optimized setups approaching around a hundred-fold. That’s why fifty-fold is the representative figure for how much sensitivity is boosted. Keep in mind that the exact gain depends on reagent concentrations, incubation times, and tissue/background conditions, so protocols may vary.