NEUTROPHIL ATTRACTANT PROTEIN-1 INTERLEUKIN-8 AND ITS AUTOANTIBODIES IN IGA NEPHROPATHY/

Human neutrophil attractant protein-1/interleukin 8 (IL-8) has been sh own to activate neutrophils to degranulate in vitro and to be a potent chemotactic agonist for neutrophils and Igmphocytes in vitro and in v ivo. There is accummulating evidence that neutrophils are involved in inflammatory injury in IgA nephropathy (IgAN), We studied the serum le vels of IL-8 and its autoantibodies of the IgA or IgG class in 36 pati ents with IgAN in comparison with 31 healthy controls and 26 patients with other primary glomerulonephritides (CGN). Interleukin 8 was more frequently detected in sera of patients with IgAN and their serum leve ls were significantly higher than those of healthy controls. The free IL-8 autoantibodies of the IgA, but not IgG class, were more frequentl y detected in patients with IgAN and their serum levels were significa ntly elevated compared with both groups of controls. The complexed IL- 8 autoantibodies of either class were not different among the three gr oups of subjects, Again the ratio of free to complexed IL-8 autoantibo dies of the IgA class was raised in patients with IgAN. Histologic exa mination revealed increased polymorphs and monocyte/macrophage infiltr ation in IgAN compared with other glomerulonephritides. When the serum levels of IL8 and IL-8 autoantibodies were compared between IgAN pati ents with milder pathology and those with more severe pathology, the l atter group had significantly higher serum levels of free and complexe d IL-8 autoantibodies of the IgA class. These observations suggest a p ossible role for IL-8 and its autoantibodies of the IgA class in the i nflammatory process of IgAN. These autoantibodies may provide a clinic ally useful marker for the diagnosis of disease severity. (C) 1996 Aca demic Press, Inc.