Chronic Myeloid Leukaemia: Evidence for Basophil Differentiation and Histamine Synthesis from Cultured Peripheral Blood Cells

We have attempted to assess basophil differentiation in vitro in 15 patients with chronic myeloid leukaemia (CML). Using a sensitive radioassay, whole blood histamine values were found to be elevated in 10 of 14 patients tested, and correlated well with peripheral blood basophil counts (r=¿70). In seven of nine CML patients, but not in controls, total histamine content of separated peripheral blood cells suspended in a modified Marbrook system was shown to rise after 7 d in vitro. Further study showed that both histamine (mean, five-fold increase) and basophils (mean, three-fold increase) were significantly elevated over control values at 1, 2 and 3 weeks in vitro. Total cell-associated histamine content (in pg per 100 viable cells) was greater in CML cultures than in controls at 3 weeks (P less than 0.01). Serial cultures of cells from one patient revealed substantial in vitro rises in basophils and histamine at an accelerated, but not at a chronic, phase of disease. Cells from this patient and two others studied at the time of blast crisis demonstrated higher indices of basophil and histamine increases when compared to the group of CML patients in chronic phases of the disease (P less than 0.05). We conclude that basophil precursors exist in increased numbers in the peripheral blood of CML patients. Assays for basophil differentiation may prove useful in following disease activity in this and other myeloproliferative disorders.