The glomerular distribution of laminin and fibronectin in glomerulonephritis

Laminin (LAM) and fibronectin (FI) are regarded as major components of the glomerular extracellular matrix. The aim of this study was to define the distribution of LAM and FI in primary glomerulonephritis (GN) and GN of systemic lupus erythematosus (SLE) and to correlate the type of glomerular disorders with possible changes in the expression of these components. Normal portions of kidney tissue from 10 patients with renal tumors and sixty-six renal biopsies obtained from patients with GN were studied by the immunoperoxidase-antiperoxidase (PAP) method for the detection of LAM and FI. Twelve patients had membranous GN (MGN), 8 mesangiocapillary GN (MCGN), 21 mesangioproliferative GN (MPGN), including 11 cases of IgA nephropathy, 11 focal segmental glomerulosclerosis (FSGS) and 14 had SLE. In MGN, LAM was detected more intensely than FI along the glomerular basement membranes (GBM), in subepithelial GBM protrusions and in the newly-formed GBM. On the contrary, FI was intensely expressed in the mesangium. LAM and FI expression was pronounced in stages II and III of MGN. In MCGN, LAM and FI were diffusely expressed along the GBM and in the mesangium. The distribution of the two antigens in MPGN and FSGS was similar to that seen in normal glomeruli. However, the FI staining reaction was more intense in severe mesangioproliferative lesions, mainly observed in the cases of IgA-nephropathy. There were no differences in the distribution of LAM and FI between primary and SLE GN. The antigen staining pattern was pronounced in the membranous and mesangiocapillary lesions of SLE GN.(ABSTRACT TRUNCATED AT 250 WORDS)