CDS+ B cells predominate early in ontogeny and bare been associated with autoantibody production. In chronic lymphocytic leukemia (CLL), B lymphocytes express CD5 and frequently produce autoantibodies using developmem~ Jly rcgzdated:'ariable (V)-gene segments. Does the selfreactivity observed in CLL reflect transformation of a'fetal'lineage of cells, or could overexpansion cf these B cells occur as a consequence of antigen s, imulation~. Harry Schroeder and Guillermo Dighiero have rel, ieu, ed the literature describing antibody sequences in CLL and have compared them with the'fetal'repertoire. This analysis indicates that CLL cells use a repertoire characteristic of mature cells, and suggests that antigen may play a role in tt, e pathogenesis of this disease.

Chronic banphocytic leukemia (CLL) is a hematological neoplasm that results from an accumulation of B lymphoc. vtes with a mature phenotype. CLL B cells frequently express typical B-cell markers, such as CD19, CD20, CD21, CD24 and CD37 (reviewed in Ref. 1). Although heavy-(H)-chain class switching has been reported in CLL, most CLL B cells express either IgM alone or both lgM and IgD on their cell surface. Furthermore, CLL B cells can be distinguished from other B-cell neoplasias by their characteristic phenotype: low amounts of surface immunoglobulin (slg)