Tonsillar distribution of IgA and IgG immunocytes and production of IgA subclasses and J chain in tonsillitis vary with the presence or absence of IgA nephropathy.

At the onset or in the course of IgA nephropathy (IgA NP), upper respiratory tract infections and tonsillitis are often followed by periods of gross haematuria. In a search for possible abnormalities in the tonsillar IgA- and IgG-cell system, the palatine tonsils from seven patients with IgA NP and eight controls, all 15 suffering from chronic recurrent tonsillitis, were subjected to an immunohistochemical study. Compared with the controls, tonsils of NP patients contained a significantly (P less than 0.001) increased proportion of IgA-producing cells (49.6% versus 35.7%). There was also an increase (P less than 0.001) in the ratio of IgA polymer- (J-chain-positive) to monomer-producing cells in NP tonsils compared with controls (35.0% versus 18.8%). Although the tonsillar IgA cells were generally producing mainly IgA1, this subclass was even more predominant in NP tonsils (P less than 0.03). These results are compatible with the hypothesis that in some patients with IgA NP, the polymeric IgA1 deposited in the mesangium may be of tonsillar origin.