IMMUNOLOGIC ASSAY FOR THE PHILADELPHIA TRANSLOCATION

OVER 96 PERCENT OF ALL CHRONIC MYELOGENOUS LEUKEMIA (CML) AND 17 TO 25 PERCENT OF ALL ACUTE LYMPHOBLASTIC LEUKEMIA PATIENTS HAVE A PHILADELPHIA (PH') CHROMOSOME IN THEIR LEUKEMIC CELLS. AS THE PRESENCE OF THE PH' CHROMOSOME HAS PROGNOSTIC AND DIAGNOSTIC IMPLICATIONS, CYTOGENETICAL ANALYSIS IS PERFORMED ON BONE MARROW SPECIMENS OF THESE PATIENTS. THE OBJECTIVE OF THIS PROJECT IS THE DEVELOPMENT OF AN IMMUNOLOGIC ASSAY FOR THE PH' CHROMOSOME. THE NEW ASSAY WILL BE SUPERIOR TO CURRENT CYTOGENETICAL ANALYSIS IN TERMS OF ACCURACY, RAPIDNESS, AND COST-EFFECTIVENESS. THE FEASIBILITY OF DEVELOPING SUCH AN ASSAY IS BASED ON THE FOLLOWING: AS A DIRECT CONSEQUENCE OF THE PH' TRANSLOCATION,TWO GENES, THE BCR GENE AND THE C-ABL ONCOGENE ARE FUSED ON THE PH'-CHROMOSOME; THIS CHIMERIC GENE ENCODES A CHIMERIC BCR-C-ABL PROTEIN. IN PHASE I, IMMUNOLOGIC REAGENTS WILL BEMADE USING BOTH SYNTHETIC BCR-C-ABL PEPTIDES, AND TRYPE-BCR OR C-ABL PROTEINS SYNTHESIZED IN E. COLI. THESE ANTISERA WILL BE EVALUATED FOR THEIR ABILITY TO DETECT THE CHIMERIC PROTEIN USING AS TESTER CELLS THE CELL LINE K562, ESTABLISHED FROM A CML PATIENT IN BLAST CRISIS. IN PHASE II, THE REAGENTS WILL BE UTILIZED FOR DETECTION OF THE CHIMERIC PROTEIN DIRECTLY IN PATIENT MATERIAL AND THE FORMATTING OF AN ASSAY SUITABLE FOR CLINICAL USE.