The vascular cell adhesion molecule (VCAM-1) is expressed on a subset of lymphoid and myeloid leukaemias

The expression of the vascular cell adhesion molecule (VCAM-1), recently identified as cytokine-inducible ligand of the beta 1-integrin VLA-4, was investigated on normal and malignant haemopoietic precursors as well as on haemopoietic cell lines. VCAM-1 was demonstrated on > 20% blasts in 4/22 acute myeloid leukaemia (AML) and 6/10 acute lymphoblastic leukaemia (ALL) specimens but was absent from CD34+ normal bone marrow precursor cells. Interestingly, the VCAM-1+ AMLs classified as M1 and M5 simultaneously expressed N-CAM (CD56), a member of the immunoglobulin family. In ALL, VCAM-1 expression was restricted to Calla+ CD19+ precursors of the c-ALL subtype. VCAM-1 was also found on some cell lines, mainly of the B-lymphocytic type. Furthermore, in 13/20 chronic lymphocytic leukaemia (CLL) samples > 20% of the CD19+ B-lymphocytic precursors carried VCAM-1, which seemed to correlate with more advanced disease. Therefore VCAM-1 expression appeared to characterize leukaemic cells of the B-cell lineage as well as a CD56+ subset of AML. Since its expression was clinically correlated with dermal infiltrates of leukaemic cells in AML and with advanced Rai stages in CLL, VCAM-1 may play a role in enhanced adhesion of the malignant cells to tissues and/or to each other.