CD8 expression in a case of chronic lymphocytic leukemia with trisomy 12.

We report a case of B-cell chronic lymphocytic leukemia (B-CLL) with aberrant expression of the T-cell-associated antigen CD8, as revealed by two-color flow-cytometric analysis. DNA studies showed immunoglobulin heavy-chain gene rearrangement, but not of gamma-chain T-cell receptor, confirming the B-cell origin of the neoplastic cells. Ploidy analysis showed a tetraploid population and high S-phase fraction. B-CLL cells also carried trisomy 12, detected by fluorescence in situ hybridization. The identification of more cases with the same features would be necessary to establish the prognosis of this subtype of B-CLL.