DIFFERENTIAL ADHESIVENESS BETWEEN BLOOD AND MARROW LEUKEMIC-CELLS HAVING SIMILAR PATTERN OF VLA ADHESION MOLECULE EXPRESSION

Functional adhesion of blood and marrow leukemic cells from 14 acute m yeloid leukemia patients presenting with hyperleukocytosis was evaluat ed by performing cytoadhesion assays on purified (:extracellular matri x proteins) and non-purified supports (MRCS fibroblastic cell line). R esults, in 30-min chromium release assay, show a mean +/- S.D. adhesio n to fibronectin, collagen, and laminin respectively of 30 +/- 17%, 20 +/- 13%, 25 +/- 17% for blood leukemic cells and 18 +/- 11%, 11 +/- 1 0%, 11 +/- 8% for marrow leukemic cells. These differences between blo od and marrow cells were statistically significant (respectively P = 0 .005, P = 0.01 and P = 0.002), while no difference was noted regarding adhesion to non-purified supports. The higher adhesion of blood blast cells to purified supports was observed regardless of CD34 expression . No significant difference was observed in the expression of cell sur face VLA-molecules (CD29, CD49b, CD49d, CD49e, CD49f) between blood an d marrow blast cells. The addition of GM-CSF or G-CSF induced increase d adhesion of marrow blasts and decreased adhesion of blood blasts lea ding to a loss of the difference between blood and marrow cells. In a 60-min chromium release assay, marrow lasts adhered even more than blo od leukemic cells to fibronectin. In contrast, marrow blasts from 'ale ukemic' acute myeloid leukemia patients did not show any modification regarding their adhesion to extracellular matrix proteins when co-cult ured with growth factors. (C) 1998 Elsevier Science Ltd. All rights re served.