Adhesion receptors on peripheral blood leukemic B cells. A comparative study on B cell chronic lymphocytic leukemia...

The expression of a series of adhesion receptors: L-selectins (CD62L): Leu-8, several integrins (LFA-1: CD11a/CD18, VLA-4: CD49d/CD29 and VLA-5: CD49e/CD29), ICAM-1(CD54) and the 'homing receptor' (CD44) were investigated by a dual color flow cytometry in 56 cases of B cell disorders namely, 39 chronic lymphocytic leukemias (CLL), four hairy cell leukemia (HCL), seven splenic lymphoma with villous lymphocytes (SLVL) and six other non-Hodgkin's lymphoma (NHL). The functional activity of L-selectins was assessed with L-selectin ligand analogs (polyphosphomonester core polysaccharide: PPME and fucoidin). Leukemic B cells were identified with phycoerythrin-conjugated monoclonal antibodies (McAbs) anti-CD19, anti-kappa/lambda investigated simultaneously for the expression of adhesion receptors estimated with fluorescein-isothiocyanate (FITC) conjugated McAbs. The percentage of leukemic cells expressing L-selectins (Leu-8) was high in CLL (52% of positive cases) and integrin expression (LFA-1, VLA-4, 5) was low (19 and 33%, respectively), while a reverse pattern, low Leu-8 (17%), and a high VLA-4 (77%), was observed in non-CLL cases. The expression of LFA-1 alpha-chain was variable in non-CLL cases, and the LFA-1 heterodimer was expressed on most clonal B cell in NHLs (92%). LFA-1 alpha-chain was detected on cells from only one HCL case, while beta2 integrin was regularly expressed on hairy cells. VLA-5 integrin was found on a relatively small number (26%) of mature B cell leukemias. A remarkable finding was the detection of ICAM-1 in all CLL cases albeit the number of positive cells was significantly lower (P < 0.05) compared to non-CLL cases. CD44 was expressed on a high number of neoplastic cells in all the investigated categories. There was no correlation between the expression of the adhesion molecules and clinical and laboratory parameters except for CD18 which was expressed on a significantly (P < 0.05) higher number of leukemic cells in CLL with more advanced stages. This study demonstrates that even closely related B cell leukemia/lymphomas have a certain well defined and strictly variable adhesion profile which is characteristic of the disease entity and therefore, the adhesion profile may offer additional information useful for differential diagnosis and study of disease pathogenesis.