BACKGROUND: During the relapse of multiple sclerosis, the activation ofT cells, autoreactive to myelin antigens in blood, enhanced and maintained as a result of anomalous mechanismsof their earlier elimination, leads on para- and autocrine basis to the activation of antigen- non-specificcells of immune system. In consequence, activated cells secrete a range of proinflammatory cytokinesand display activation antigen expression on their surface, which results in blood-brain barrier damage.The differentiation of lymphocytes into effector cells in blood during MS relapse is to increase thenumber of cells supporting inflammatory reactions and simultaneously to reduce the number of cells whichplay a role of suppressors. Fas antigen is present among activation antigens found on T cells. Once thisantigen has been combined with the ligand, it transmits apoptic signal to the cell. The presence of Fasantigen on activated peripheral blood T cells may enable us to estimate their activation and it may alsoindicate a potential to eliminate those cells from blood. The aim of the study was to provide a quantitativeassessment of the subpopulations of CD3, CD4 and CD8 lymphocytes in peripheral blood and to investigateFas antigen expression on these subsets in patients with relapsing-remitting multiple sclerosis, in relationto clinical activation of the disease.
MATERIAL AND METHODS: Thirty-five patients participated in thestudy, including 14 patients finding themselves in clinical relapse of the disease and 21 patients inthe state of remission. Additionally, 21 healthy subjects were included. Quantitative assessment of individualsubpopulations and Fas co-expression was carried out with the use of monoclonal antibodies anti CD3,CD4 and CD8 as well as anti CD95 antibodies, and flow cytometer Pas/Dako Galaxy.
RESULTS: The differencesin the percentage of particular lymphocytes between 3 groups proved insignificant. Patients in the relapseof the disease showed significantly greater Fas expression on subpopulations CD3 and CD4 when comparedto the results obtained from remission patients and control subjects. This difference was not observedfor Fas expression on subset CD8.
CONCLUSIONS: The investigation of Fas receptor expression may be usefulin order to monitor clinical course of the disease, which is characterised by the periods of exacerbationand remission.

Keywords: Multiple Sclerosis, Fas antigen, T cells