Anaphylatoxin formation during hemodialysis: Effects of different dialyzer membranes

Abstract Anaphylatoxin formation during hemodialysis: Effects of different dialyzer membranes. Measurable complement activation resulting in the formation of both C3a and C5a anaphylatoxins was observed in 12 patients undergoing maintenance dialysis treatment with cuprophan hollow fiber dialyzers. Specific radioimmunoassay measurements demonstrated that these patients displayed significantly elevated levels of C3a antigen in the venous (outflow) line of the dialyzer after only 2 min of dialysis. During hemodialysis, venous plasma C3a levels continued to increase and became maximally elevated after 15 min. Thereafter, C3a concentrations gradually declined, suggesting that the rate of complement activation abates with continued cuprophan hemodialysis. Complement activation, as judged by venous plasma C3a levels, was also temporally correlated with hemodialysis leukopenia. The factor believed to be responsible for pulmonary vascular leukosequestration, C5a, could also be detected in venous plasma, but levels of this antigen were not strikingly elevated until the later stages of dialysis. By contrast, six patients dialyzed with polyacrylonitrile dialyzers failed to exhibit hemodialysis leukopenia and displayed only very modest increases in their plasma C3a levels during the initial phases of hemodialysis. These observations provide direct evidence that anaphylatoxin formation during hemodialysis is a transient phenomenon and indicate that the biocompatibility of dialysis membranes, as reflected by their complement activating potential, may be significantly different. Formation d'anaphylatoxines pendant l'hemodialyse: Effets de differentes membranes de dialyseurs. Une activation mesurable du complement, aboutissant a la formation d'anaphylatoxines C3a et C5a ete observee chez 12 malades en hemodialyse periodique avec des dialyseurs a fibres capillaires en cuprophan. Des mesures radioimmunologiques specifiques ont demontre que ces malades avaient des niveaux significativement eleves d'antigenes C3a dans la ligne veineuse (sortie) du dialyseur apres 2 min seulement de dialyse. Pendant l'hemodialyse, les concentrations plasmatiques veineuses de C3a ont continue a augmenter, et sont devenues maximales apres 15 min. Ensuite, les concentrations de C3a ont diminue progressivement, suggerant que la vitesse de l'activation du complement diminue pendant la poursuite de l'hemodialyse au cuprophan. L'activation du complement, jugee par les concentrations plasmatiques veineuses de C3a, etait egalement reliee dans le temps avec la leucopenie de l'hemodialyse. Le facteur suppose etre responsable de la leucosequestration vasculaire plumonaire, le C5a, etait egalement detectable dans le plama veineux, mais les niveaux de cet antigene n'etaient pas eleves de facon marquee avant les stades tardifs de la dialyse. A l'inverse, six malades dialyses avec des dialyseurs en polyacrylonitrile n'ont pas eu de leucopenie de l'hemodialyse, et n'ont montre que des augmentations tres modestes de leur niveau plasmatique de C3a pendant les phases initiales de l'hemodialyse. Ces observations apportent une preuve directe que la formation d'anaphylatoxines pendant l'hemodialyse est un phenomene transitoire et indiquent que la biocompatibilite des membranes de dialyse, refletee par leur potentiel d'activation du complement, pourrait etre signifiicativement differente.