The influence of low dose recombinant interleukin-2 (rIL-2) therapy on immunological system of patients previously treated with purine analogues.

MM Malek,MD, A.Dmoszynska MD, PhD, A.Goracy MSc, D.Jawniak MD, W.Legiec MD.

Department of Haematooncology and Bone Marrow Transplantation Center, University Medical School in Lublin, Poland

AIM: The aim of the study was to reconstitute the immune system in heavily suppressed patients previously treated with purine analogues, using very low dose of interleukin-2 (IL-2) and to correlate the effect of therapy with the incidence of infections. METHODS: We analyzed fourteen patients with B-cell proliferations, who previously received 3 to 9 cycles of chemotherapy based on 2-CdA or fludarabine. They displayed signs of infections and the amounts of CD4, CD8 and NK cells in the blood less than 400 cells in & microliter;(0,4 G/l). All patients received 1.8 x 106 IU of IL-2 daily, subcutaneously during two weeks. Patients received totally 3 cycles of a two-week IL-2 therapy. Before and after each IL-2 cycle we studied the expression of lymphocyte subpopulations and IL-2 receptors in the blood using flow cytometry technique. RESULTS: During IL-2 therapy we revealed continuous increase of CD4, CD8 and NK cells comparing to the amounts of these lymphocytes before IL-2 therapy. The increase of all lymphocyte subsets was already seen after first cycle of IL-2 and in case of CD4 lymphocytes and NK cells it reached statistical significance. After the end of IL-2 treatment we observed statistically significant increase of NK cells and close to significant increase of CD4 and CD8 lymphocytes. The increase of IL-2 receptors was marked but without statistical significance. In 50% of patients decreased incidence of infections was observed. The number of all infectious episodes after IL-2 therapy was about two times reduced, compared to 10 months period before IL-2 treatment. Low-dose IL-2 appeared as well tolerated therapy with severe side-effects seen only in two patients. CONCLUSION: It seems that IL-2 in a dose as low as 1.8 x 106 IU/day is sufficient to boost the immune response in immunodeficient patients.

KEY WORDS: interleukin-2, immunotherapy, purine analogues.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Immunotherapy.