Impaired neutrophil defense against Yersinia enterocolitica in patients with iron overload who are undergoing dialysis.

Increased risk that patients with iron overload who are undergoing dialysis will have bacteremia caused by Yersinia enterocolitica has previously been shown. Iron overload is known to increase the virulence of Y. enterocolitica. Whether alterations of the phagocyte defense against this organism are also involved has not yet been determined. We compared neutrophil defense against a serum-resistant strain of Y. enterocolitica in three groups of individuals: nine patients receiving hemodialysis who had iron overload (group 1), nine patients receiving hemodialysis who did not have iron overload (group 2), and 10 healthy controls (group 3). Y. enterocolitica phagocytosis and killing were studied in the presence of autologous or pooled normal human serum. Phagocytosis was significantly decreased in group 1 compared with that in the other two groups. The use of normal serum for opsonization did not improve the phagocytosis function. Killing was moderately decreased in the group 1, but only in the presence of autologous serum. We conclude that in patients with iron overload who are undergoing dialysis, the high frequency of Yersinia bacteremia is attributable not only to increased virulence of this microorganism but also to disturbances of the mechanisms specifically involved in the neutrophil defense against Yersinia invasion.