Expression of B-Cell-Associated Antigens on Acute Lymphoblastic Leukemia Cells

Abstract

The diagnosis of acute leukemia consists of morphological FAB classification, genetic abnormality assay, cytochemical analysis, and immunophenotype based on surface and cytoplasmic expression of antigens of blastic cells.^1-6 The commonly used immunophenotypic classification of acute lymphoblastic leukemia (ALL) includes null ALL (only HLA-DR and/or CD19 antigens are present on blast surface), common ALL (HLA-DR, CD19, and CD10 expression on blasts), and pre-B subtype with cytoplasmic μ chain in CD10, HLA-DR, and CD19 positive cell.^1,2,4,7 The heterogeneity of early B-cell differentiation antigens expression (atypical patterns) was described in a few cases, more often in null ALL subtype.^3,5 It suggested that the earliest stages of B-cell development showed less stable antigen expression. The clinical meaning of this heterogeneity was unknown.^6,8