Interferon gamma- and interleukin-4-secreting cells in multiple sclerosis.

Interleukin 4 (IL-4)- and interferon gamma (IFN gamma)-secreting peripheral blood cells were enumerated by immunospot assay in 13 multiple sclerosis (MS) patients during exacerbations, in 24 patients with progressive multiple sclerosis (CPMS), and in 20 controls. Cells that spontaneously secreted IFN gamma were significantly higher in MS patients experiencing an attack (P < 0.001) than in controls or in CPMS (P < 0.04). IL-4-secreting cell numbers were elevated significantly and to a comparable extent in both MS groups compared to controls. Our finding of increased numbers of IFN gamma-secreting cells is in keeping with prior work showing increased IFN gamma levels in the circulation prior to and during MS attacks and increased release of IFN gamma to the supernatant in bulk cultured blood cells from MS patients. What role an increase in IL-4-secreting cells might play in MS is unclear, but it could relate to immune system regulation. Following in vitro exposure to MBP, IFN gamma-secreting cell number rose above levels observed in the absence of stimulation in controls and in both MS groups with the rise in acutely exacerbating MS patients being significantly greater than in controls. Our results provide further evidence for reactivity to MBP in MS, the significance of which in terms of pathogenesis remains clouded.