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.