A comparison using quantitative enzyme cytochemistry between leucocyte alkaline phosphatase levels in the bone marrow...

Leucocyte alkaline phosphatase (LAP) levels have been compared in neutrophil polymorphs in bone marrow and blood in the rat, using a quantitative enzyme cytochemical technique. It has been shown that LAP levels are higher in bone marrow than blood, both in normal animals and those with experimentally-induced local inflammatory lesions. In the latter group both marrow and blood LAP levels were higher than in controls; blood levels rose because of the outpouring of cells with moderately high LAP levels into the blood and marrow levels rose because only cells with very high LAP levels remained. The inverse relationship between neutrophil age and alkaline phosphatase content, previously demonstrated in the peripheral blood of the rat, has also been shown to exist in the bone marrow.