ADHESION MOLECULES ON CD34+ HEMATOPOIETIC-CELLS IN NORMAL HUMAN BONE-MARROW AND LEUKEMIA

Expression of selected adhesion molecules of the integrin and immunoglobulin family was investigated on CD 34 + leukemic cells in 19 AML and 11 ALL cases to evaluate phenotypic differences in adhesive properties of malignant hematopoietic precursor cells in comparison to normal bone marrow CD 34+ cells. Of the beta2-integrin family, CD 11 a was expressed on > 50% of CD 34 + cells in normal bone marrow and almost all leukemias, whereas CD 11 b and CD 11 c were not expressed on CD 34 + cells in normal bone marrow, but were found on CD 34 + blasts in some leukemias of a heterogeneous immunophenotype. Of the beta1-family, CDw 49 d (VLA-4) was strongly expressed on normal CD 34+ bone marrow cells and on the blasts of all 30 CD 34+ leukemic samples, whereas CDw 49 b (VLA-2) was absent on CD 34+ cells in normal bone marrow, but detected on CD 34+ cells in a few leukemias which did not constitute a clinical or phenotypic entity according to the FAB classification or immunocytological analysis. The lymphocyte-homing-associated adhesion molecule CD 44 (HCAM) and CD 58 (LFA-3) were expressed on CD 34+ cells in all investigated cases of normal and leukemic bone marrow. ICAM-1 (CD 54), the inducible receptor ligand for CD 11 a/CD 18, although present on CD 34+ cells in normal bone marrow, was lacking on blast cells of some ALL and AML cases. So far, the variable expression of beta2-integrins as well as of VLA-2 and of ICAM-1 could indicate distinct differences in cell-cell or cell-matrix adhesion of leukemic cells in ALL and AML patients.