Immunophenotypic and molecular genetic characterization of a case of CD8+ B cell chronic lymphocytic leukemia.

We report the case of a patient with chronic B lymphocytic leukemia, with stable clinical and hematological conditions in the absence of any treatment. The flow cytometry analysis of the patient's cells revealed a CD19+, CD5+, IgM+, IgD+, lambda chain-phenotype, along with an unusual expression of CD8 alpha/alpha homodimer. B cells did not stain with the anti CD8 beta monoclonal antibody T8/2T8 5H7. Molecular biology analyses confirmed the monoclonal rearrangements of immunoglobulin heavy and lambda light chain genes in the presence of a germline configuration of T cell receptor genes. Moreover, an abnormal configuration of the CD8A gene was found in the CD8+B lymphocytic clone. We suggest that the aberrant expression of the CD8 gene could be related to its abnormal configuration.