Relationship between T200 antigen expression and stages of B cell differentiation in resurgent hyperplasia of bone marrow

Using monoclonal antibodies (MoAbs) and dual-parameter flow cytometric techniques, bone marrow mononuclear cells (MMC) from patients with resurgent hyperplasia were analyzed for their coexpression of HLe-1 (T200) and antigens normally associated with particular stages of B cell differentiation. The marrow from those with resurgent hyperplasia contained increased numbers of B cell precursors in multiple stages of differentiation compared to controls, thus providing a useful model system for studies of B cell differentiation. These studies indicate that the quantitative expression of T200 is differentiation-related on normal and malignant B cells and B cell precursors. Immature cells express low amounts of T200, while increasing levels of maturity correlated with increasing amounts of the antigen. This study increases the understanding of relationships between B cell surface antigens and T200 and further demonstrates that B cell hyperplasia occurs commonly in association with bone marrow reactive or resurgent processes. The quantitative, rather than only the qualitative, expression of T200 is therefore a useful marker of B cell differentiation in reactive hyperplasia and in further investigation of B cell malignancy.