Coexistent Polycythemia Vera and Chronic Lymphocytic Leukemia: Down-Regulation of Myeloid Clone by the Lymphoid Clone?

Abstract

Coexistence of polycythemia vera (PV) and chronic lymphocytic leukemia (CLL) is a rare association. The clinical course in all cases has been remarkably mild, thus suggesting suppression and/or control of each disease by the other.

We have studied a patient who exhibited a typical feature of PV for 6 years. After 3 years of remission, induced by ³²P, a mild form of PV reappeared in association with B-CLL. In order to investigate the possible influence of CLL to the mild expression of PV, we have performed several in vitro colony assays and the tumor necrosis factor (TNF) assay. Colony formation by patient's bone marrow hematopoietic progenitor cells showed “spontaneous” BFU-E and CFU-E. In addition, patient's plasma selectively inhibited growth of normal BFU-E and CFU-E colony formation. TNF bioactivity, analysed during the course of the disease, was reduced. These findings suggested the existence of an inhibitor of erythropoiesis that could be involved in a down regulation of the myeloid clone by the lymphoid clone in this patient.

Keywords:

• PV
• CLL
• inhibitor of erythropoiesis