Suppression of vascular injury at the Arthus reaction site by a complement inhibitor, 5,5',5''-(1,3,6-naphthalene-triyl-tris[sulfonylimino])-tris (1,3-benzene disulfonic acid) hexasodium salt.

A novel polyanionic complement inhibitor 5,5,5''-(1,3,6-naphthalene-triyl-tris[sulfonylimino])-tris(1 ,3-benzene- disulfonic acid) hexasodium salt (compound IIb) was tested for its ability to suppress vascular injury at the site of the Arthus reaction (AR). In control animals in which AR was evoked without drug treatment, venules at AR sites ranged from normal (arbitrarily defined as stage I) to destroyed (stage V). Between these two ends of the spectrum were venules with an accumulation of cells and deposits of electron dense material (stage II), accumulations of cells and deposits and small endothelial gappings (stage III), and accumulations of cells and depositions which had spread into perivascular tissue and small gappings (stage IV). In animals treated with compound IIb, the AR stopped at stage III or IV depending on the dose, it never reached stage V. In other words compound IIb treatment resulted in protection of endothelium, basal lamina and other structures from the destruction which is characteristically observed in the AR. The effect of high doses of compound IIb was similar to that described before for suramin.