Infectious complications after simultaneous pancreas-kidney transplantation: a role for the lectin pathway of complement activation.

BACKGROUND Mannose-binding lectin (MBL) is a recognition molecule of the lectin pathway of complement activation, and its serum levels are largely determined by frequently occurring polymorphisms of the MBL gene. We questioned whether MBL deficiency influences infectious complications in patients after simultaneous pancreas-kidney transplantation (SPKT). METHODS Infectious complications in the first year after transplantation were scored retrospectively in 152 consecutive SPKT patients who received their transplant at our center between 1990 and 2005. Pretransplant serum MBL levels were determined with enzyme-linked immunosorbent assay. RESULTS Every 500 ng/mL increase in baseline MBL was associated with an odds ratio of 0.83 (P=0.045) for urinary tract infections and an odds ratio of 0.68 (P=0.029) for urosepsis. Urosepsis was significantly more common in patients with low baseline MBL (<400 ng/mL) compared with those with greater MBL levels (22.7% vs. 8.3%, P=0.015). No significant influence of MBL on the occurrence of wound infections and cytomegalovirus disease could be demonstrated. CONCLUSIONS With the current study, we show that high levels of serum MBL are associated with protection against urinary tract infections and, more specifically, against urosepsis after SPKT. These data indicate an important role for the lectin pathway of complement activation in antimicrobial defense in these transplant recipients.