Natural killer cell number and activity in remission phase of systemic connective tissue diseases

The proportions and numbers of peripheral blood mononuclear cell markers and peripheral blood NK cell activity were analyzed and correlated in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and Sjögren's syndrome (SS) patients in the remission phase of the diseases. In comparison to the control data, the number of CD56+ cells was significantly increased in RA patients only; the same held true for double-positive cells, i.e., the alterations did not distinguish various subpopulations of NK cells. NK cell activity was significantly decreased in all the three groups of patients, with the complete lack of correlation between the NK cell number and their activity. It is possible that a significantly diminished NK cell activity in these diseases provokes a compensatory production of nonfunctional NK cells.