Induction of B-cell chronic lymphocytic leukaemia and hairy cell leukaemia like phenotypes by phorbol ester treatment of normal peripheral blood B-cells.

To investigate the relationship between normal B-cells, B-cell chronic lymphocytic leukaemia (B-CLL) cells and hairy cell leukaemia (HCL) cells the three cell types were incubated with phorbol myristic acetate (PMA). The parameters studied were morphology, immunophenotype and tartrate resistant acid phosphatase (TRAP). PMA stimulation of B-cells induced morphological changes as well as CD5, CD11c, B-ly 7 and TRAP positivity. The cells formed small aggregates, the cell membranes were ruffled and frequently hairy and a small number of cells became plastic adherent and developed dendritic structure. CD5 and CD11c appeared on day 2, imitating a B-CLL phenotype. On day 3 and 4 a decrease of CD5, an increase of CD11c and the appearance of B-ly 7 could be seen mimicking an HCL phenotype. The changes in B-CLL and HCL upon PMA stimulation were mainly morphological: the B-CLL cells became ruffled and aggregated strongly, while the HCL cells developed dendritic features and became adherent. The immunophenotype of the PMA stimulated HCL cells did not change. The B-CLL cells remained CD5 positive and did not become B-ly 7 positive. The findings indicate that although PMA stimulation of normal peripheral blood cells results in CLL- as well as HCL-like phenotypes, similar stimulation of B-CLL cells does not result in an HCL-like phenotype.