The PRAME gene encodes an antigen recognized by autologous T lymphocytes and is expressed in trophoblasts, testis and frequently in human solid cancers and acute leukemias, making it a candidate for immunotherapy and for detecting MRD. We demonstrate expression of PRAME by RT-PCR in the peripheral blood or bone marrow of 26% of 58 patients with CLD (38 cases of CLL, 4 cases of PLL and 16 cases of NHL). Seven out 16 cases of MCL, 2 out 4 of PLL and 6 cases of CLL demonstrated some degree of gene expression. Thus, CLD are among the hematopoietic malignancies for which PRAME may be the target of immunological therapy or used to evaluate MRD. The stronger and more frequent expression of PRAME in MCL is apparently an additional distinguishing feature on this group of lymphoproliferative disorders. (C) 2002 Elsevier Science Ltd. All rights reserved.275393396