low and high cd8 positive t cells in multiple sclerosis patients.

cumulating evidence points to a key role for cd8+ t cells in the pathogenesis of multiple sclerosis.cd8 expression level was believed to be present constantly on the surface of human peripheral blood t cells. however, it was shown that peripheral blood lymphocytes may be divided by the level of cd8 expression, into cd8+high and cd8+low t cells. now it is well established that the cd8low population of cd8+ t cells demonstrates an activated effector phenotype while the cd8+high t cells have been reported to have regulatory function. in this report we used a flow cytometric assay to compare the frequency of these two subsets in multiple sclerosis patients (n=31) with healthy age- and gender-matched controls (n=18). we found that cd8+ t cells and cd8+low t cells significantly increased in secondary progressive (sp) and primary progressive multiple sclerosis (ppms) patients in comparison to controls (p<0.0002 and p<0.004 respectively) and also rrms (p<0.005 and p<0.017 respectively). these results demonstrated the role of cd8low t cells in progressive form of multiple sclerosis.