The development of glomerular crescents in sheep.

Renal allografts were transplanted into 10 sheep with pre-existing experimental autoimmune glomerulonephritis. Serial biopsy samples were examined by light, electron and immunofluorescence microscopy. Sections were stained with naphthyl acetate to demonstrate non-specific esterase activity. Host antiglomerular basement membrane antibody was demonstrated in graft glomeruli only 30 min after transplantation, at which time up to 40% of glomeruli contained many intracapillary neutrophils. Three d after transplantation gaps in the glomerular basement membrane were evident and the urinary spaces contained polymorphonuclear leucocytes, red blood cells, large amounts of fibrin and occasional mononuclear leucocytes. These mononuclear cells had increased greatly in number by the 6th d and most contained phagocytic vacuoles. From the 7th to the 10th d the incidence of glomerular crescents increased to involve 80% of glomeruli, and the majority of cells within crescents showed phagocytic vacuoles. The number of cells exhibiting non-specific esterase activity increased markedly during the post-operative period and most were located within the urinary spaces. These results suggest that the majority of cells in the glomerular crescents were macrophages which were probably derived from blood monocytes.