Effects of retinoic acid and phorbol ester on lymphocytes and monocytes in B-lymphocytic leukemia

PBMC concentrated from 12 patients with CLL were incubated for up to 6 days with various doses of TPA or RA in an attempt to induce differentiation. The results show a great heterogeneity in the cellular response to both inducers. TPA produced two major changes in B-CLL cells, namely the development of some hairy-cell leukemia features with an increase in Ig secretion and the expression of Leu M5 and TAC receptors. In contrast to TPA, RA induced only modest or no changes in surface, but increased numbers of large macrophages were seen as assessed by latex-bead ingestion, expression of Fc receptors and cytochemistry. These changes were more obvious after exposure to RA than to TPA. Thus, while TPA induces mostly differentiation and hairy-cell features in B-lymphocytes, RA induces activation of the monocyte pool with no obvious changes in the lymphocytic compartment.