EXPRESSION OF THE CEA GENE FAMILY MEMBERS NCA-50 90 AND NCA-160 (CD66) IN CHILDHOOD ACUTE LYMPHOBLASTIC LEUKEMIAS (ALLS) AND IN CELL-LINES OF B-CELL ORIGIN/

The carcinoembryonic antigen (CEA) and the classical nonspecific cross -reacting antigens (NCAs) belong to the CEA gene family which is part of the immunoglobulin superfamily. In normal hematopoiesis, CEA gene f amily members (CGMs) have only been reported on cells of myeloid and m onocytic origin. In the present study, we analyzed 62 childhood acute lymphoblastic leukemias (ALLs) and seven surface immunoglogulin positi ve (sig+) B-cell lines for the expression of the CEA family members CE A, NCA-50/90, NCA-95, NCA-160, CGM1 and CGM7. We demonstrated that mem bers of the CEA family were present in 76% of childhood ALLs of B- and T-cell origin. In ALLs of B-cell origin, 82% of the samples expressed at least one CEA subgroup member: 38% NCA-50/90 (CD66c), 31% NCA-160 (CD66a), and 13% both. Six of seven B-cell lines solely expressed NCA- 160. In seven ALL of T-cell origin, sole NCA-160 expression was presen t in 29% of the cases. CEA and CGM1 were not expressed in childhood AL Ls or in the sIg+ B-cell lines. In 15 ALLs and seven B-cell lines whic h could be analyzed for CGM7 expression, the antigen was not detected. NCA-95 was not expressed in 91% of the B-lineage ALLs, in T-lineage A LLs and in the B-cell lines. However, five B-lineage ALLs showed confl icting data on the binding patterns of two, on leukocytes specifically NCA-95 recognizing antibodies suggesting either expression of unknown forms of NCA-95 or NCA-50/90 or of a yet unknown member of the CEA fa mily in these ALL cells. The expression of CEA subgroup members in chi ldhood ALL cells might have prognostic impacts, as an inverse correlat ion exists between NCA expression on leukemic blasts and the risk fact or white blood count at diagnosis.