Natural killer cell activity in dermatomyositis-polymyositis.

We examined the baseline natural killer (NK) function and its modulation by interleukin-2 (IL-2) in 16 patients with dermatomyositis/polymyositis (DM/PM). Patients with active untreated disease had low baseline NK activity, while in patients with inactive and untreated disease, it was akin to the controls. Patient's cells with low NK activity responded less to IL-2 than those with normal NK activity. Studies at the single cell level revealed decreased target binding and killing cells with a normal recycling capacity. Our findings indicate an association between disease activity and decreased NK function in patients with DM/PM that could play a role in its association with malignancy.