COMPARABLE PROFILES OF THE IMMUNOGLOBULIN HEAVY-CHAIN COMPLEMENTARITY-DETERMINING REGION (CDR)-3 IN CD5(-) HUMAN CORD-BLOOD B-LYMPHOCYTES()AND CD5()

It has been suggested that CD5(+) B cells are closely related to the p athogenesis of autoimmune disease or chronic lymphocytic leukaemia, wh ereas the origin and physiological role of CD5(+) B cells remain contr oversial. To study the molecular differences between CD5(+) and CD5(-) B cells in terms of immunoglobulin gene structure, we sorted both sub sets from new-born cord blood and analysed the complementarity determi ning region (CDR)-3 profiles of the immunoglobulin heavy chain (IgH) g ene. The CDR-3 sequences from both CD5(+) and CD5(-) B cells represent ed the same incidence and length of N-region, and the same usage of D and J(H) segments. When translated into amino acids, 24 of 32 clones ( 75%) and 25 of 37 clones (65 . 8%) from their respective subset were p roductive, and the composition of the deduced amino acids were similar between both subsets. These data suggest that CD5(+) B cells are not a distinct lineage presenting a biased immunoglobulin repertoire in B cells.