Interferon-gamma secretion by peripheral blood T-cell subsets in multiple sclerosis: Correlation with disease phase and interferon-beta therapy

Interferon-gamma (IFN-gamma) is implicated as a participant in the immune e ffector and regulatory mechanisms considered to mediate the pathogenesis of multiple sclerosis (MS). We have used an intracellular cytokine staining t echnique to demonstrate that the proportion of ex vivo peripheral blood CD4 and CD8 T-cell subsets expressing IFN-gamma is increased in secondary prog ressing (SP) MS patients, whereas the values in untreated relapsing-remitti ng (RR) MS patients are reduced compared with those of controls. Patients t reated with interferon-beta (IFN-beta) have an even more significant reduct ion in the percentage of IFN-gamma-secreting cells. The finding that the nu mber of IFN-gamma-expressing CD8 cells is increased in SPMS patients, a gro up with reduced functional suppressor activity, and is most significantly r educed by IFN-beta therapy, which increases suppressor activity, indicates that IFN-gamma secretion by CD8 T cells and functional suppressor defects a ttributed to this cell subset in MS can be dissociated.