Circulating immune complexes in patients with gram negative septic shock

Summary In order to explain complement components abnormalities observed during septic shock, circulating immune complexes (C.I.C.) were searched for in sera from 34 patients with gram negative sepsis by two different methods: polyethylene glycol precipitation test based on physical properties of C.I.C. and C1q deviation test based on the property of radiolabelled C1q to react with C.I.C. Serum immunoglobulins (IgG, IgA, IgM) and complement components (C1q, C3, C4) levels were simultaneously determined. Seventeen patients with minimal haemodynamic abnormalities had normal or increased levels (except C4 at 62% of normal) and in eleven cases both tests for C.I.C. were simultaneously positive. Seventeen patients with severe septic shock had a decrease in IgG, IgM, C1q, C3 and C4 and none had both tests for C.I.C. simultaneously positive (P<10^–4). The disappearence of C.I.C. in patients with severe septic shock associated with evidence of complement activation suggests their involvement in the pathogenesis of septic shock in man.This work was supported by grants from Conseil Scientifique de l'Université Paris Val de Marne and Délégation Générale de la Recherche Scientifique et Technique, Contracts N° 7510954 and 7771396