A recent phenotyping study that performed cytometric staining for multiple cell surface markers revealed lower frequencies of circulating CD8lowCD56 + CD3-CD4- cells in untreated patients with relapsing–remitting multiple sclerosis or clinically isolated demyelinating syndrome than in healthy controls . The MS relapses and new brain lesions detected by magnetic resonance imaging are often preceded by a reduction in PB NK cell functional activity , but similar percentages of PB NK cells were detected in treated MS patients when compared to non-MS patients despite decreased frequency of CSF NK cells .