Background: Multiple scleroisis is presumably cell-mediated autoimmune disorder with immune abnormalities as presence of activated T-cells and increase interleukin 2 (IL-2) and soluble IL-2 receptor (sIL-2R) levels in central nervous system and peripheral blood of patients. The aim of immunosuppressive treatment is to diminish such activation. The aim of this study was to evaluate the influence of immunosuppressive cladribine treatment with total dose of 2.1 mg/kg b.w. administered in 7 cycles for 12 months, on serum leucocytes in 34 chronic progressive multiple sclerosis (CPMS) patients observed for 2 years as well as IL-2 and sIL-2R serum levels assessed before and right after the treatment.
Material/Methods: The study was designed as a randomised, placebo-controlled, double-blind trial. The patients were divided in two groups: group I, cladribine-treated, n&eguals;34; group II, placebo-treated, n&eguals;35. Group III were healthy controls, n&eguals;20. Leucocyte levels were determined with flow-cytometry. IL-2 and sIL-2R levels were assessed with enzyme-linked immunosorbent assay.
Results: Statistically significant gradual decrease of lymphocyte level was observed from 7th week to 12th month after the beginning of treatment. During the following 12 months, lymphocyte levels remained decreased in comparison to baseline. Mean values of IL-2 and sIL-2R levels measured 12 months after the treatment were found to be lowered by 20%(p.&eguals;0.01) and by 24% (p.&eguals;0.0005), respectively.
Conclusions: The results obtained indicate fast and long-lasting decrease of serum leucocyte level and suppressive influence of cladribine treatment on immune processes in multiple sclerosis patients.

Keywords: Multiple Sclerosis, cladribine, Interleukin-2, soluble interleukin-2 receptor