Clinical implications of linear immunofluorescent staining for immunoglobulin G in patients with diabetic nephropathy

The kidneys of patients with diabetes mellitus usually exhibit a characteristic pattern of linear immunofluorescent staining for immunoglobulin G (IgG) along the glomerular and tubular basement membranes. However, the association between linear IgG staining and the renal prognosis remains unclear.

Among 223 patients with diabetes who underwent renal biopsy from 1985 to 2010 and were confirmed to have pure diabetic nephropathy according to the classification of Tervaert et al., 165 patients (glomerular classes I to III) were enrolled in this study. Immunofluorescent staining was classified into three categories according to its intensity (0=none, 1=weakly positive, and 2=positive). Cox proportional hazards regression analysis was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for death-censored renal death, with each regression analysis employing four levels of multivariate adjustment.

After adjustment for important clinical factors at the time of renal biopsy, the HR for death-censored renal death in patients with an IgG staining score of 1 or 2 was, respectively, 3.01 (95% CI: 1.05-8.68) and 4.68 (1.67-13.1) compared with patients who had a staining score of 0. Even after adjustment for clinical variables and pathological findings, the HR for IgG score of 1 or 2 was higher than that for an IgG score of 0, and it was, respectively, 2.22 (0.71-7.00) and 3.76 (1.27-11.2).

More intense linear IgG staining is associated with a higher HR for renal death, which suggests that linear immunofluorescent staining for IgG may be a prognostic indicator in patients with diabetic nephropathy.