Background: The relationship between tonsillar autoimmune response and the pathogenesis of IgA nephropathy (IgAN) has been previously demonstrated. However, the role of CD4 (+)CD25 (+)Treg cells, which play critical roles in maintaining peripheral tolerance and preventing autoimmunity, has not yet been defined in IgAN.
Methods: Thirty-five patients with IgAN and 35 patients without renal disease were studied. The CD4 (+)CD25 (+)Treg cells were examined by flow cytometry. Clinical and laboratory data, such as serum creatinine and urinary samples, were obtained from each patient. Glomerular injury was assessed by histopathology. Serum IgA, C3, IL-2, IL-4 and IL-6 were analyzed by ELISA.
Results: CD4 (+)CD25 (+)Treg cells significantly decreased in IgAN patients compared with the controls before tonsillectomy (p < 0.05). CD4 (+)CD25 (+)Treg cells were negatively correlated with blood urea nitrogen, supernatant IL-4 and proteinuria in IgAN patients, and positively with estimated glomerular filtration rate. CD4 (+)CD25 (+)Treg cells gradually decreased as the severity of renal histology increased. In addition, serum IgA, IL-2, IL-6 and supernatant IL-4 elevated while CD4 (+)CD25 (+)Treg cells decreased in IgAN patients. CD4 (+)CD25 (+)Treg cells were significantly increased when serum IgA, IL-2, IL-6 and supernatant IL-4, urine protein and urine erythrocytes were decreased after tonsillectomy in patients with IgAN, but were still lower than those of the controls (p < 0.05).
Conclusions: CD4 (+)CD25 (+)Treg cells were associated with IgAN, and tonsillectomy may increase CD4 (+)CD25 (+)Treg cells in IgAN patients, leading to clinical improvement.