Significant CD5 expression on normal stage 3 hematogones and mature B lymphocytes in bone marrow

B-cell maturation from hematogones to mature B cells in bone marrow exhibits a consistent, complex spectrum of sequential antigen expression. CD5 expression, however, has not been characterized. We studied the dynamics of CD5 expression on developing B cells by 4-color flow cytometry in 32 patients, aged 9 months to 63 years, with hematogone hyperplasia (>3.5% of total events). The mean percentage of hematogones was 8.1%. We demonstrate consistent CD5 expression on normal, polytypic B cells in a continuum, predominantly at later stages of maturation, specifically on stage 3 hematogones and mature B cells. Awareness of this normal pattern of CD5 expression on B-cell subsets has implications in the analysis of minimal residual disease of CD5+ B-lineage non-Hodgkin lymphomas.