Innate immune mechanisms in the pathogenesis of systemic lupus erythematosus (SLE)

Immune imbalance in SLE increases the susceptibility to infectious diseases . The aim of this study was to analyze several mechanisms related to non-sp ecific immunity in this autoimmune disorder. We studied in vivo CD11b expre ssion, phagocytosis, and chemotaxis in polymorphonuclear cells (PMN) from S LE patients. All tests were also performed under hrIL-8 stimulating conditi ons and analyzed by flow cytometry. Intracellular leucocyte (monocytes and PMN) enzyme activity was evaluated using specific substrates for cathepsin B and D, collagenase, and oxidative burst by flow cytoenzymology. An exagge rated in vivo CD11b expression was observed on PMN from SLE patients withou t noticeably in vitro effect upon hrIL-8. Similarly both, phagocytosis and chemotaxis were diminished and showed no response to hrIL-8 stimulation. Th e opposite was found in PMN from controls. Intracellular enzyme activity wa s comparable between groups as far as cathepsin B and D are concerned. A te ndency of;decreased oxidative-burst induction was noted in monocytes and PM N from SLE patients, whereas collagenase activity was found clearly increas ed in both leucocyte subpopulations. Our results may represent a deficient ability of the innate immune mechanisms for the clearance of infectious age nts, immune complexes, satisfactory resolution of inflammatory processes an d tissue repair in SLE. (C) 2001 Elsevier Science B.V. All rights reserved.