Nonresident macrophages are absent from glomeruli in IgA nephropathy.

The presence of nonresident cells of monocyte-macrophage lineage was investigated in 50 renal biopsies, including 20 from patients suffering from IgA nephropathy. Histochemical and immunological techniques were used to identify, respectively, nonspecific esterase and peroxidase activities and HLA class II molecules. Although intraglomerular phagocytes were observed in all control biopsies, small numbers were seen in only two samples from patients with IgA nephropathy. This feature is consistent with an impaired clearance of immune complexes, possibly leading to their deposition in the mesangium.