The effect of histamine challenge on platelet count and platelet activation

There is conflicting evidence of platelet involvement in asthmatic bronchoconstriction. We sought direct evidence of platelet activation and indirect evidence of platelet sequestration following histamine challenge (HC) in 14 asthmatics and seven non asthmatic control subjects. Peripheral platelet counts and levels of beta thromboglobulin (BTG) were measured immediately before and following HC in the 21 subjects. There were no significant differences in the platelet counts or BTG levels, before or after HC, within or between the two groups. These results do not support platelet activation or accumulation in the lungs occurring immediately following histamine induced bronchoconstriction in asthmatics.