COMPARATIVE ADHESION OF HUMAN HEMATOPOIETIC-CELL LINES TO EXTRACELLULAR-MATRIX COMPONENTS, BONE-MARROW STROMAL AND ENDOTHELIAL CULTURES

We used flow cytometry to characterize cell adhesion molecule expressi on of the human haemopoietic cell lines KG1a, K562, HL-60, NALM-6 and CEM. A (51)chromium labelling assay was used to study the adhesion of these cell lines to extracellular matrix components and to bone marrow stromal and endothelial cultures. Both adhesion molecule expression a nd functional binding behaviour varied between cell lines, All five ce ll lines expressed the integrins alpha(4) beta(1) and alpha(5) beta(1) and all adhered to fibronectin, However, differences in intensity of expression of these integrins failed to correlate with extent of fibro nectin adhesion, inhibition experiments demonstrated that adhesion of KG1a to fibronectin was completely inhibited by divalent cation chelat ion and partially inhibited by RGDS peptides and chondroitinase ABC, s uggesting that both alpha(4) beta(1) and alpha(5) beta(1) as well as C D44 were responsible for this interaction. Adhesion to bone marrow str omal and endothelial layers was superior to that to purified extracell ular matrix components and tvas partially inhibited by divalent cation chelation. RGD peptides and anti-alpha(4) monoclonal antibody also pa rtially inhibited KG1a adhesion to bone marrow endothelium. Discordanc e between cell adhesion molecule expression and adhesive behaviour sug gest that current phenotypic descriptions remain incomplete and reinfo rce the need for complementary functional binding studies.