13-CIS RETINOIC ACID INHIBITS GROWTH OF ADULT T-CELL LEUKEMIA-CELLS AND CAUSES APOPTOSIS - POSSIBLE NEW INDICATION FOR RETINOID THERAPY

We evaluated the effects of 13-cis retinoic acid (13-cis RA) on the gr owth of peripheral blood mononuclear cells (PBMC) obtained from 12 pat ients with adult T cell leukemia (ATL). In general, 13-cis RA potently inhibited the growth of PBMC from ATL patients. However, the sensitiv ity of the cells to 13-cis RA-induced growth inhibition varied among t he patients. The ATL patients fell into three groups (hypersensitive, sensitive and resistant to 13-cis RA) according to the percent reducti on of H-3-thymidine incorporation before and after treatment with 13-c is RA. Agarose gel electrophoresis of total genomic DNA from a patient sensitive to 13-cis RE provided evidence of the DNA fragmentation ind icative of apoptosis. The ability of 13-cis RA to induce apoptosis in PBMC from ATL patients suggests that retinoids may be useful in the tr eatment of ATL.