PML IS EXPRESSED IN CHRONIC GRAFT-VERSUS-HOST DISEASE LESIONS

The PML (for 'ProMyelocytic Leukemia') gene product is a nuclear zinc finger protein, identified when the chromosomal translocation fusing t his gene to the retinoic acid receptor was found in acute promyelocyti c leukemia. Recently, a frequent occurrence of autoantibodies against the PML protein was detected in primary biliary cirrhosis (PBC) sera, suggesting that this protein could represent an autoantigenic trigger in PBC, Chronic GVHD features are close to those of PBC and in additio n, antinuclear and antinucleolar antibodies are frequently detected in patients' sera, In order to determine if an abnormal expression of PM L, followed by the development of anti-PML antibodies, can be implicat ed in chronic GVHD pathogenesis, we studied the expression of PML in t he skin of seven patients with chronic GVHD as well as the presence of circulating anti-PML antibodies. PML was highly expressed by the lesi onal skin keratinocytes, but circulating antibodies were never detecte d, PML is induced by interferon (IFN)gamma, The expression of PML by G VHD epidermis is likely secondary to the IFN gamma produced by infiltr ating lymphocytes, Since PML display growth suppressor properties, the role of this protein in tissue lesions is discussed.