Histamine uptake by leukocytes in vitro.

Human leukocytes at the concentration of 10(6) cells/ml were incubated for 1h at 37.5 degrees C in a tris-albumin buffer, containing 0, 6.25, 12.5, 25, 50, and 100 micrograms/ml of histamine. Histamine uptake was measured by a photofluorometric method. We found that the leukocytes take up exogenous histamine and attain respective intracellular concentration of 307%, 423%, 438%, 1000% and 645% above controls. It was found that neutrophils and eosinophils possess the greatest capacity to take up exogenous histamine whereas, contrary to the expectation, basophils display poor capacity.