Hypocomplementemia in kidney transplant recipients: impact on the risk of infectious complications.

The usefulness of monitoring of complement levels in predicting the occurrence of infection in kidney transplant (KT) recipients remains largely unknown. We prospectively assessed serum complement levels (C3 and C4) at baseline and at months 1 and 6 in 270 patients undergoing KT. Adjusted hazard ratios (aHRs) for infection in each posttransplant period were estimated by Cox regression. The prevalence of C3 hypocomplementemia progressively decreased from 21.5% at baseline to 11.6% at month 6 (p = 0.017), whereas the prevalence of C4 hypocomplementemia rose from 3.7% at baseline to 9.2% at month 1 (p = 0.004). Patients with C3 hypocomplementemia at month 1 had higher incidences of overall (p = 0.002), bacterial (p = 0.004) and fungal infection (p = 0.019) in the intermediate period (months 1-6). On multivariate analysis C3 hypocomplementemia at month 1 emerged as a risk factor for overall (aHR 1.911; p = 0.009) and bacterial infection (aHR 2.130; p = 0.014) during the intermediate period, whereas C3 hypocomplementemia at month 6 predicted the occurrence of bacterial infection (aHR 3.347; p = 0.039) in the late period (>6 month). A simple monitoring strategy of serum C3 levels predicts the risk of posttransplant infectious complications in KT recipients.

Monitoring of immunoglobulin levels identifies kidney transplant recipients at high risk of infection.

We aimed to analyze the incidence, risk factors and impact of hypogammaglobulinemia (HGG) in 226 kidney transplant (KT) recipients in which serum immunoglobulin (Ig) levels were prospectively assessed at baseline, month 1 (T(1) ), and month 6 (T(6) ). The prevalence of IgG HGG increased from 6.6% (baseline) to 52.0% (T(1) ) and subsequently decreased to 31.4% (T(6) ) (p < 0.001). The presence of IgG HGG at baseline (odds ratio [OR] 26.9; p = 0.012) and a positive anti-HCV status (OR 0.17; p = 0.023) emerged as risk factors for the occurrence of posttransplant IgG HGG. Patients with HGG of any class at T(1) had higher incidences of overall (p = 0.018) and bacterial infection (p = 0.004), bacteremia (p = 0.054) and acute pyelonephritis (p = 0.003) in the intermediate period (months 1-6). Patients with HGG at T(6) had higher incidences of overall (p = 0.004) and bacterial infection (p < 0.001) in the late period (>6 month). A complementary log-log model identified posttransplant HGG as an independent risk factor for overall (hazard ratio [HR] 2.03; p < 0.001) and bacterial infection (HR 2.68; p < 0.0001). Monitoring of humoral immunity identifies KT recipients at high risk of infection, offering the opportunity for preemptive immunoglobulin replacement therapy.