Segmental staining of the murine nephron by monoclonal antibodies directed against the GP-2 subunit of laminin.

Monoclonal antibodies to GP-2, the 220,000-dalton subunit of laminin, were used in an immunohistologic study to investigate structural variations in basement membranes. Mouse kidney was used because of the wide range of basement membranes represented. Two rat/mouse monoclonal antibodies, designated LAM-I and LAM-II were compared with rabbit polyclonal anti-GP-2 in a light and electron microscopic study that identified nephron segments by morphology, by topography, and by the use of markers specific for individual segments. LAM-I staining is demonstrable on all tubular and glomerular basement membranes but not on those of blood vessels or smooth muscle, differing in this respect from anti-GP-2. LAM-II staining is confined to the basement membranes of the convoluted portion of proximal tubule segments (S1 and S2), not the straight (S3) portion; to the thin limb and the thick ascending limb of Henle's loop, but not distal convoluted tubules or collecting ducts. The heterogeneity of GP-2 localization may be due to differing conformations of the molecule at these sites.