Monoclonal Antibodies Specific to the Acute Lymphoblastic Leukemia t(1; 19)-Associated E2A/pbx1 Chimeric Protein: Characterization and Diagnostic Utility

Abstract

Nonrandom chromosomal abnormalities are found in most human malignancies, particularly leukemias and lymphomas. A characteristic t(1; 19) (q23; p13.3) chromosomal translocation is detected in 5% of childhood acute lymphoblastic leukemia (ALL) cases. This translocation results in the formation of a fusion gene, which leads to the expression of an oncogenic E2A/pbx1 protein. Breakpoints in the E2A gene almost invariably occur within a single intron, and the identical portion of PBX1 is joined consistently to exon 13 of E2A in fusion mRNA. In this article, we report the development of monoclonal antibodies against E2A/pbx1 fusion protein using a specific peptide that corresponds to the junction region of the protein. The obtained antibodies recognize specifically the chimeric E2A/pbx1 fusion protein and lack cross-reactivities with E2A and pbx1. Immunohistochemical staining and flow cytometric studies show that these antibodies can distinguish t(1; 19)-positive from t(1; 19)-negative leukemic cells. These results indicate that the obtained E2A/pbx1-specific monoclonal antibodies might prove to be valuable diagnostic reagents and important tools for elucidating the mechanisms involved in oncogenesis and progression of t(1; 19)-positive childhood ALL.

Investigation of Minimal Residual Disease in Childhood and Adult Acute Lymphoblastic Leukaemia by Molecular Analysis

“…The translocation results in a chimaeric fusion gene consisting of the transcription activating motif of E2A and the DNA‐binding homeodomain of PBX1 (Hunger et al , 1991; Kamps et al , 1990; Nourse et al , 1990). Polyclonal (Berendes et al , 1995) and monoclonal antibodies (Sang et al , 1997) have been successfully used for the identification of ALL cases carrying this translocation. These could be used for screening cases with failed cytogenetics in which no material is available for molecular analysis.…”