SERUM IMMUNOGLOBULIN-E IN PRIMARY IGA NEPHROPATHY

The biosynthesis of human immunoglobulin E (IgE) is regulated by a com plex network involving T and B lymphocytes. Diseases associated with h igh serum IgE (sIgE) levels are usually characterized by T cell disord ers. Total sIgE level has been found to be of clinical relevance in mi nimal change nephrotic syndrome. However, the clinical significance ha s rarely been studied in primary IgA nephropathy (IgA N). We retrospec tively studied 99 cases of primary IgA N. There were 59 males and 40 f emales with a mean age of 30.0 +/- 12.1 years. The mean follow-up dura tion was 45.9 +/- 31.1 months. Pathological grading was done according to the criteria of Meadow et al. Median sIgE for the entire group was 122.0 IU/ml (range: 2.8-5805 IU/ml) which was significantly higher th an the healthy control group (median: 43,7 IU/ml, range: 5.0-1003 IU/m l, p < 0.001). However, when the IgA N cases were stratified into grad es, only grade I(median: 514 IU/ml, range: 72.1-5805.0 IU/ml) and grad e II (median: 229 IU/ml, range: 5.0-5464 IU/ml) patients had significa ntly higher sIgE than the control group (p < 0.0005 and p < 0.001 resp ectively). Patients with nephrotic ranged proteinuria (32 cases) were further classified into ''stable'' and ''progressive'' groups. The ''s table'' group had a significantly higher sIgE level(median: 922.0 IU/m l, range: 2.8-5805 IU/ml), compared to that of the ''progressive'' gro up (median: 55.3 IU/ml, range: 5.0-1600 IU/ml, p < 0.02), The effect o f aggressive treatment (including corticosteroid and/or cyclophosphami de, cyclosporine) was also assessed. The ''responsive'' group had a si gnificantly higher serum IgE (median: 728.0 IU/ml, range: 2.8-5805 IU/ ml) than the ''resistant'' group (median: 41.5 IU/ml, range: 5.9-1600 IU/ml, p < 0.01). We conclude that the sIgE level is elevated in IgA N patients with mainly grade I and Il lesions which may imply a differe nt pathogenetic mechanism in this subpopulation. The level of sIgE can serve as a good prognostic indicator in IgA N patients with nephrotic ranged proteinuria, A high serum IgE level indicates a milder patholo gical change, and a better response to aggressive treatment.