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Patch tests were carried out to evaluate the presence of a sensitization to some components of dialytic circuits in 17 uremic patients complaining of pruritus of unknown origin. Fragments of different dialyzer membranes, of tubing sets, of dialyzer membranes recently resterilized with ethylene oxide and the International Contact Dermatitis Research Group standard series substances were tested. Neither patients nor healthy subjects reacted positively to patch tests, which leads us to question the role of contact allergy in the determination of uremic pruritus.

The Fc-receptor function of macrophages and monocytes was studied in 10 healthy subjects and 10 patients (5 in phase of clinical activity) affected by systemic vasculitis with histological evidence of renal involvement. Macrophage function was detected by measuring the clearance in vivo of IgG-sensitized 51Cr-labelled autologous red blood cells (RBC). In vitro immune phagocytosis of monocytes was analysed as a kinetic phenomenon by incubating IgG-coated RBC with nearly pure suspensions of peripheral monocytes. All 5 patients studied in phase of clinical activity showed a defective Fc-receptor function in both the assays, as compared with normal subjects. Since a good correlation was found between the in vitro and the in vivo methods, the use of this non-invasive in vitro procedure is proposed as a substitute for the radioactive in vivo techniques in monitoring the course of the above disease.

Twenty-one patients with primary IgA nephropathy, 7 patients with Henoch-Schönlein nephritis and 4 patients with IgA nephropathy associated to alcoholic liver cirrhosis were tested for Fc-receptor phagocyte function by measuring the clearance of radiolabelled IgG-sensitized erythrocytes in vivo and the immune phagocytosis by monocytes in vitro. Meanwhile IgG-, IgA-, IgA1-, IgA2-, containing immune complexes, the complement components C3, C4, C3d and the HLA-A, B, DR phenotype were determined. The patients with major urinary abnormalities were well discriminated from those with only minimal hematuria by a defective macrophage function (p less than 0.01) and high levels of IgA immune complexes (p less than 0.02). Since non HLA-A, B, C, DR phenotype was prevalent in patients who had defective Fc-receptor function, whereas a significant correlation was found between Fc-receptor impairment and levels of IgA immune complexes, it appears likely that circulating blocking factors, possibly related to IgA containing immune materials, may impair macrophage function in IgA nephropathies.

Much attention has been devoted to the development of clinically applicable ways of detecting immune complexes (IC) in the circulation. Through a reliable IC assay it is hoped to obtain information about the pathogenesis, diagnosis and prognosis of human glomerulonephritis. The authors present a critical re-evaluation of their own data, with a follow-up of 1–42 months. The authors’ experience refers to 428 sera from 207 patients affected by idiopathic or secondary glomerulonephritis. In the last 4 years 3 tests for the detection of circulating IC were employed: solid phase C1q test, PEG precipitation test and PMN immunohistological technique. The limits and specificity of each test and the diagnostic significance of the data obtained in nephropathic patients are discussed.

Since IgA nephropathy can be experimentally induced by alimentary antigens, mechanisms of oral immunization might be supposed also in human primary IgA nephropathy (PIgAGN). IgA immune complexes (IgAIC) are thought to play a major role in PIgAGN, hence this parameter was monitored in six PIgAGN patients subjected to diets excluding gluten, meat or eggs respectively and selected as having persistent urinary activity and high IgAIC levels. On gluten-free diet IgAIC significantly decreased over 3 different periods of 10 days (Student's t-test p 1 less than 0.03, Rank-Signed test p 2 less than 0.02), 1 month (p 1 less than 0.007, p 2 less than 0.02) and 6 months (p 1 less than 0.05, p 2 less than 0.02). IgAIC significantly increased again on a gluten containing diet over 1 month (p 1 less than 0.008, p 2 less than 0.04) and 3 months (p 1 less than 0.02, p 2 less than 0.04). After 6 months on a gluten-free diet, all patients had normal IgAIC values and decreased IgA2 subclass-IgAIC, in agreement with the hypothesis of withdrawal of an antigen challenging the mucosal immune system. These data indicate a relationship between a gluten-containing diet and high levels of IgAIC in PIgAGN patients, suggesting that dietetic factors might play a role in the different geographical distribution of this nephropathy.

Five patients with progressive primary IgA nephropathy (PIgAGN) were treated by plasma-exchange (PE) combined with immunosuppressive drugs. Circulating IgA-containing immune complexes (IgAIC), detected by a specific conglutinin solid phase assay, were monitored. Two patients with acute nephritic syndrome and rapidly progressing course, crescent formations and high levels of IgAIC had substantial lasting clinical improvement after several PE, with a fall in IgAIC levels. Another rapidly progressive case with marked sclerotic changes and a longer history of nephritic syndrome, but with normal levels of IgAIC, did not show any clinical improvement after PE. Two patients with a PIgAGN diagnosed several years before and presenting slowly evolutive course had no substantial clinical benefit from PE treatment. IgAIC levels, very high before PE temporarily decreased, but returned to the previous values after the end of the treatment. We conclude that PE combined with immunosuppressive treatment may be of clinical benefit for cases with acute nephritic syndrome of recent onset who still have high levels of IgAIC, even when important crescent formations are present.