A case report: CD8 expression in B-cell chronic lymphocytic leukemia (B-CLL). Prognostic significance of the aberrant CD8 expression

The human CD8 molecule is usually expressed on T lymphocytes or natural kil ler cells but not on normal B cells. Over a course of 5 years, we followed a case of B-CLL which aberrantly expressed the CD8 molecule. During this pe riod, the clinical and hematological conditions of the patient were stable. This B-CLL presented a typical immunophenotype (HLA DR+, CD19+, CD5+, CD23 +) with monotypic expression of surface immunoglobulin light chain kappa. W e confirmed the CD8 expression on these leukemia cells by using double labe lling and different antibodies directed against this antigen. We measured t he quantitative expression of the CD8 molecule. The number of CD8 molecules per cell was clearly lower on these malignant B cells than on normal T lym phocytes. In order to evaluate the prognostic significance of this CD8 expr ession, we quantitated in parallel other markers such as CD5, CD23, CD22, C D11c. During 5 years, this aberrant CDS expression persisted and was associ ated with an increase of the CD23 and a decrease of CD22 levels, known to c orrelate with. a good prognosis in agreement with the karyotype analysis. A ltogether our results led us to conclude that the aberrant CD8 expression i n this case of B-CLL may correlate with a non-aggressive form of lymphoprol iferative disorder.