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 (T1), and month 6 (T6). The prevalence of IgG HGG increased from 6.6% (baseline) to 52.0% (T1) and subsequently decreased to 31.4% (T6) (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 T1 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 16). Patients with HGG at T6 had higher incidences of overall (p = 0.004) and bacterial infection (p < 0.001) in the late period (>6 month). A complementary loglog 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.