Correlation among WHO classes, histomorphologic patterns of glomerulonephritis and glomerular immune deposits in SLE

In addition to the conventional World Health Organization (WHO) classification of lupus glomerulonephritis (GN), various concomitant approaches have been introduced in the evaluation of renal biopsies of patients with systemic lupus erythematosus (SLE) in order to increase the impact of biopsies on the decision concerning the most appropriate therapy as well as for establishing the prognosis. Three hundred and seventy kidney tissue samples from 267 SLE patients were analysed using standardised light, electron and immunofluorescence microscopic techniques. In 155 patients, a comparative clinical follow-up study and statistical analysis were performed. The study highlighted the heterogeneity of WHO classes IV and III, which include 5 and 6 different conventional histomorphologic types of GN, respectively. Mixed membranous and proliferative GN associated with "full-house" mesangial-transmembranous immune deposits, demonstrated in more than one third of our SLE cases, appears to be diagnostically most characteristic. Immune deposits distributed in the glomeruli in five different patterns, obviously play a major role in the pathogenesis of various WHO classes and histomorphologic types of lupus GN. Additional mechanisms related to the occurrence of antiphospholipid antibodies and antineutrophil cytoplasmic antibodies are suggested to contribute to the histomorphologic heterogeneity of WHO class III and IV lupus GN, particularly to the development of thrombotic, necrotising and crescentic glomerular lesions. In the present study, a statistically significant association was demonstrated between increasing mean values of the activity index and glomerular deposit distribution patterns labeled by subendothelial deposits. Furthermore, a significant correlation was established between an increasing risk of developing renal failure and increasing mean values of the chronicity index. Differences in the increasing risk of developing renal failure between groups with different histomorphologic types of GN and different immune deposit distribution patterns were not statistically significant. The surprisingly high renal survival rate of more than 80% noted in lupus patients with predominantly necrotising crescentic GN during the mean follow-up period of 40 months appears to be related to the more aggressive treatment of those patients. Our study confirmed a significant role of the WHO classification of lupus GN in the decision concerning the most appropriate treatment and prognostication. An increasing risk of irreversible renal failure in patients with WHO class IV lesions in contrast to those of WHO class III and in contrast to those of the category incorporating all other WHO classes was shown to be statistically significant.