Interleukin-2 receptor expression on blood monocytes of patients with multiple sclerosis.

We studied the expression of class II MHC product (HLA DR) and IL-2 receptor on circulating monocytes (M phi) in MS patients, neurological and healthy controls, by double color flow cytometry. In all groups most M phi were DR+ without significant differences. More interesting, low percentages of IL-2+ M phi were detectable in healthy and neurological controls, whilst a few MS patients with active disease showed higher levels. This finding is in agreement with similar studies in other T-cell mediated diseases and with the report of rare IL-2+ macrophages in MS plaques. Although the actual role of IL-2+ M phi in the immune response still needs elucidation, our findings suggest their relevance to the pathological process of demyelinating disease.