Circulating CD56dim NK cells expressing perforin are increased in progressive multiple sclerosis.

In this study we evaluated the percentages of CD3(-)CD56(bright), CD3(-)CD56(dim), CD3(-)CD56(bright)perforin(+) and CD3(-)CD56(dim)perforin(+) Natural Killer (NK) cells in peripheral blood from untreated secondary progressive (SP) and primary progressive (PP) multiple sclerosis (MS) patients and age and sex matched healthy subjects. Both PPMS patients and SPMS patients showed increased percentages of circulating CD3(-)CD56(dim)perforin(+) NK cells than healthy subjects. The increased percentage of CD3(-)CD56(dim) NK cells expressing perforin in patients affected by the progressive forms of MS suggests a possible role of this NK cell subpopulation in the pathogenesis of the disease.