Immunological abnormalities in the tonsils of patients with IgA nephropathy: inversion in the ratio of IgA: IgG bearing lymphocytes and increased polymeric IgA synthesis.

In the last few years the mucosal origin of the IgA deposited in the kidneys of patients with IgA nephropathy has been examined by several investigators. We have previously presented evidence that polymeric IgA may have a predominant role in the pathogenesis of IgA nephropathy. Taking into account that these patients often present with macroscopic haematuria following respiratory tract infections we have studied the possible existence of immunological abnormalities in the tonsils of patients with IgA nephropathy. Six patients and 13 controls suffering from chronic tonsillitis were submitted to tonsillectomy. Patients with IgA nephropathy showed a significant increase (P less than 0.00025) in IgA bearing lymphocytes (14.4 +/- 2.3) and a significant decrease (P less than 0.025) in IgG bearing lymphocytes (20.5 +/- 4.6) compared to the control group (2.9 +/- 1.4 and 31.6 +/- 3.6, respectively). After 7 days of culture with pokeweed mitogen the percentage of tonsillar cells producing polymeric IgA was significantly higher in the patients than in the controls (66.5 +/- 12.6 vs 33.4 +/- 10.3; P less than 0.005). These results also suggest a mucosal origin for the IgA deposited in the kidneys of these patients. Our data are consistent with the existence of an immunoregulatory dysfunction in the secretory immune system of patients with IgA nephropathy.