ADHESION RECEPTORS ON PERIPHERAL-BLOOD LEUKEMIC B-CELLS - A COMPARATIVE-STUDY ON B-CELL CHRONIC LYMPHOCYTIC-LEUKEMIA AND RELATED LYMPHOMA LEUKEMIAS/

The expression of a series of adhesion receptors: L-selectins (CD62L): Leu-8, several integrins (LFA-1: CD11a/CD18, VLA-4: CD49d/CD29 and VL A-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 diso rders 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 o f L-selectins was assessed with L-selectin ligand analogs (polyphospho monester core polysaccharide: PPME and fucoidin). Leukemic B cells wer e identified with phycoerythrin-conjugated monoclonal antibodies (McAb s) anti-CD19, antikappa/lambda investigated simultaneously for the exp ression of adhesion receptors estimated with fluorescein-isothiocyanat e (FITC) conjugated McAbs. The percentage of leukemic cells expressing L-selectins (Leu-8) was high in CLL (52% of positive cases) and integ rin expression (LFA-1, VLA-4, 5) was low (19 and 33%, respectively), w hile a reverse pattern, low Leu-8 (17%), and a high VLA-4 (77%), was o bserved in non-CLL. cases. The expression of LFA-1 alpha-chain was var iable in non-CLL cases, and the LFA-1 heterodimer was expressed on mos t clonal B cell in NHLs (92%). LFA-1 alpha-chain was detected on cells from only one HCL case, while beta 2 integrin was regularly expressed on hairy cells. VLA-B integrin was found on a relatively small number (26%) of mature B cell leukemias. A remark able finding was the detec tion of ICAM-1 in all CLL cases albeit the number of positive cells wa s significantly lower (P < 0.05) compared to non-CLL cases. CD44 was e xpressed on a high number of neoplastic cells in all the investigated categories. There was no correlation between the expression of the adh esion molecules and clinical and laboratory parameters except for CD18 which was expressed on a significantly (P < 0.05) higher number of le ukemic cells in CLL with more advanced stages. This study demonstrates that even closely related B cell leukemia/lymphomas have a certain we ll defined and strictly variable adhesion profile which is characteris tic of the disease entity and therefore, the adhesion profile may offe r additional information useful for differential diagnosis and study o f disease pathogenesis.