Plasma histamine elevation in a large cohort of sickle cell disease patients.

The role of mast cells has been questioned in sickle cell disease (SCD). We performed a prospective study evaluating plasma histamine and tryptase levels in a cohort of paediatric and adult patients, in steady state (n = 132) and during vaso-occlusive crisis (VOC) (n = 121). Histamine level was elevated in 18% of patients in steady state and in 61% during VOC. Median histamine level was significantly higher during VOC than in steady state (24 center dot 1 [7 center dot 0-45 center dot 0] vs 9 center dot 6 [6 center dot 2-14 center dot 4] nmol/l, P < 0 center dot 0001). Tryptase level was slightly increased during VOC without reaching pathological values. These results suggest a role of mast cell activation in SCD pathophysiology.