Phenotypic and functional analysis of natural killer cells in systemic lupus erythematosus patients

Systemic lupus erythematosus (SLE) manifested with multiple autoantibodies production and glomerulonephritis, is the best example of systemic autoimmune diseases. To further elucidate the role of cytokines and the potential involvement of natural killer cells (NK cells) in the pathogenesis of lupus, phenotypic analysis of peripheral blood mononuclear cells (PBMC), NK cells cytotoxicity and cytokines production pattern of SLE patients and normal controls were examined. In addition, the effect of a variety of cytokines on anti-dsDNA antibodies production was also investigated. Our results showed that: (a) there was an increased percentage of memory T cells and decreased percentage of NK cells in SLE patients when compared to normal controls (p < 0.05); (b) a decreased production of cytokines like gamma-IFN in mitogen-stimulated PBMCs was also noted in SLE patients; (c) cytolytic activity of NK cells was markedly reduced in SLE patients (p < 0.05); (d) spontaneous secretion of IgG anti-dsDNA antibodies by B cells isolated from SLE patients could be inhibited by gamma-IFN, but not by IL-2, IL-4 and IL-5. These data suggested that decreased functions of NK cells and related type 1 T helper cells be closely related to the immune dysregulation and autoantibodies production in SLE.