Redistribution of natural killer (NK) cell frequency and NK cytotoxic activity in primary IgA nephropathy.

Recent findings have indicated an imbalance of immune responsiveness in primary IgA nephropathy (IgAN). Thus natural killer (NK) cell frequency and NK cytotoxicity were evaluated in fifteen IgAN patients. CD8+, CD11+, CD56+ and CD57+ lymphocyte percentages in IgAN individuals fell within normal values, while a significant decrease of CD16+ cells was observed in the same group of patients. In contrast, NK activity overlapped that seen in controls as assessed by an agarose-single cell cytotoxic assay. To further investigate the discrepancy between CD16+ cell level and NK cytotoxic activity in IgAN, the proportion of CD11+ CD57+, CD56+ CD16+ and CD57+ CD16+ lymphocytes was determined. In spite of the unaffected CD56+ CD16+ cell frequency, IgAN subjects exhibited a significant decrease of CD11+ CD57+ and CD57+ CD16+ lymphocyte percentages in comparison to controls. It is suggested that a redistribution of NK lymphocyte subsets occurs in IgAN. This may have an important role in the impairment of the immunoregulatory network.