Peripheral blood lymphocyte subsets in polymyalgia rheumatica.

Peripheral blood lymphocytes from 23 patients with polymyalgia rheumatica (PMR) were characterized using monoclonal antibodies and flow cytometry in a two-year prospective study. There were no significant differences in absolute numbers or relative percentages of lymphocytes or CD3+, CD4+, CD8+ T cells or the CD4+ T cell functional subsets, virgin (CD4+CD45RA+) and memory (CD4+CD29+) T cells, in patients before or during corticosteroid treatment compared to controls. Previous reports on decreased levels of CD8+ T cells as a characteristic of PMR/giant cell arteritis was not confirmed. The absolute number and relative percentage of lymphocytes with natural killer cell activity, CD16+ CD56+ cells, were significantly lower in patients with active untreated PMR as well as during corticosteroid treatment compared to controls, but at the two-year follow-up the difference was less marked.