[Arthus-type nephritis and glomerular clearing system]

Glomerular clearing system was histologically studied to see what role it played in the flourishing, resolving and healing stages of Arthus-type nephritis in rabbits with intravenously injected colloidal carbon or ligation of thoracic duct. In the glomerulus, poorly soluble immune complexes were found within mesangial channels, a route for the egress of macromolecules from the peripheral mesangium through the hilus into the juxtaglomerular apparatus, other than phagocytosed by polymorphonuclear leukocytes. However, in the flourishing stage the immune deposits supplied to the external mesangial matrix seemed to originate in that made in the periglomerular blood capillary. Severer glomerulitis was observed under the condition of lymph stasis and juxta-glomerulitis, which was composed of inactive monocytes and plasmocytes, appeared late from the resolving stage. Coincidentally, stagnant amorphous, electron dense material was seen around the border between the external and internal mesangium or the wall of the efferent arteriole at the reflection site of Bowman's capsule. These features of juxta-glomerulitis may be explained by stagnant deposits transported upstream through mesangial channels. Carbon particles within mesangial channels were finally taken up by mesangial cells, whose endocytotic phagosome settled down until three weeks of the healing stage. Mesangial blebs or pseudopods protruding in the capillary lumen were observed in the resolving stage, the injection of colloidal carbon and the ligation of thoracic duct. The endothelium was lifted by mesangial blebs from the juxta-mesangial portion and seemed to interrupt the capillary blood stream. Mesangial influx was increased because of partly desquamation of the endothelium and macromolecules tended to accumulate in the sub-basement membrane of the para-mesangium. It's suggested that focal segmental sclerotic and adhesive lesions in the healing stage are correlated with the degree of juxta-glomerulitis and the peripheral mesangial blebs.