Histamine release upon adenosine 5 '-monophosphate (AMP) nasal provocationin allergic subjects

Background-Nasal provocation with adenosine 5'-monophosphate (AMP) elicits nasal symptoms in subjects with rhinitis. Histamine released from mast cell s may play a part in AMP induced nasal responses. Methods-Symptoms of rhinitis were recorded and histamine release in the flu id obtained by nasal lavage after AMP, guanosine 5'-monophosphate (GMP), an d placebo instillations was measured in nine subjects with allergic rhiniti s and nine non-allergic controls in a double blind, randomised, placebo con trolled study. Results-No symptoms or significant increases in histamine were observed aft er GMP and placebo challenge. Significantly higher levels of histamine were seen in the nasal lavage fluids of allergic subjects following AMP challen ge than in nonallergic controls, the median (range) histamine concentration increasing from the baseline value of 1.62 (0.44-6.99) ng/ml to 6.45 (0.81 -16.17) ng/ml at three minutes. No increase in histamine levels was seen in the non-allergic subjects in whom the median histamine concentration was 1 .13 (0.29-4.25) ng/ml at baseline and 0.97 (0.31-5.89) ng/ml three minutes after AMP challenge. Conclusions-AMP elicits an immediate rise in histamine levels in the nasal lavage fluid of allergic subjects compared with non-allergic individuals. T hese findings indicate that the exaggerated nasal response to adenosine may reflect mast cell priming in vivo, thus supporting its application as a po tential new marker of allergic inflammation.