INCREASED NUMBERS OF CIRCULATING HEMATOPOIETIC PROGENITOR CELLS AFTER TREATMENT WITH HIGH-DOSE INTERLEUKIN-2 IN CANCER-PATIENTS

Summary Immunotherapy with recombinant interleukin‐2 (IL‐2) and lymphokine‐activated killer (LAK) cells has been applied to patients with metastatic cancers for its antitumour activity. In the present study we investigated the effects of in‐vivo administration of IL‐2 (3.106 U/m2/d, continuously i.v.) on haematopoiesis. Six patients with disseminated renal cell carcinoma, treated with IL‐2 and LAK cells, were monitored for the numbers of white blood cells and circulating haematopoietic progenitor cells (HPC). During IL‐2 treatment lymphopenia developed, followed by lymphocytosis after discontinuation of IL‐2 infusions. IL‐2 administration also resulted in neutrophilia and eosinophilia. Absolute numbers of circulating HPC declined markedly during IL‐2 treatment. However, after completing IL‐2 infusions, the numbers of circulating erythroid (BFU‐E), inyeloid (CFU‐GM) and multipotential progenitor cells (CFU‐GEMM) strongly increased, reaching a maximum after 5 d (day 10 from the start of IL‐2 treatment). This increase did not result from repeated leucaphereses, since patients treated with IL‐2 alone showed a similar response. In comparison with pretreatment levels the pool of circulating HPC expanded about 20‐fold. This study illustrates that IL‐2 treatment has a biphasic effect on the frequency of circulating BFU‐E. CFU‐GM and CFU‐GEMM. causing a decrease during 11,‐2 infusion, followed by an increase after IL‐2 administration. The total number of progenitor cells harvested by four consecutive leucaphereses is in the range that is commonly used for peripheral blood stem cell autografting. Copyright © 1990, Wiley Blackwell. All rights reserved