Cytokine flow cytometry differentiates the clinical status of multiple sclerosis (MS) patients

In this study we have examined intracellular cytokines in peripheral blood mononuclear cells (PBMC) of MS patients by flow cytometry (cytokine flow cy tometry). MS progressive patients showed an increased number of cells produ cing interferon-gamma (IFN-gamma) after activation with phorbol 12-myristat e 13-acetate and ionomycin, compared with patients with clinically inactive forms (P < 0001) and with healthy controls (P = 0001). These cells belonge d to the CD4(+) and CD8(+) subsets in similar proportions. Clinically inact ive patients showed a lower level of cells producing IL-2 than controls (P = 0.03) and active MS patients (P = 0.03). Most IL-2-producing cells were C D4(+) lymphocytes, although a small part of the IL-2 was also produced by C D8(+) cells. The percentage of cells producing simultaneously IL-2 and IFN- gamma was increased in active MS and they were mainly CD4(+) lymphocytes. N o differences in the production of IL-4 were observed between groups. Howev er, we found an increased IL-10 production in clinically active MS patients (P = 0.03). Treatment with IFN-beta of active MS patients showed lower lev els of cytokines when compared with untreated MS patients. This methodologi cal approach could help in the follow up and therapeutic monitoring of MS p atients.