Kinetics of amyloid deposition. II. The effects of dimethylsulfoxide and colchicine therapy.

Amyloid (AA) protein, when deposition begins, is deposited in two stages--a rapid deposition period of 2 weeks and a plateau stage. The effect of dimethylsulfoxide (DMSO) and colchicine therapy on the kinetics of amyloid deposition was dependent on the stage of the disease at which therapy began. If given during the rapid deposition period, colchicine delayed the increase in amyloid but did not abolish it. Eventually, splenic and liver amyloid reached the level seen in untreated animals. On the other hand, DMSO given during the rapid deposition period led to significant resorption of both splenic and liver amyloid. By contrast, colchicine and DMSO given after the rapid deposition period were essentially without effect in promoting amyloid resorption. These results correlated well with the serum levels of SAA, the putative AA precursor. Colchicine given during the period of rapid AA deposition caused a transient decline in SAA levels, which eventually returned to levels seen in untreated animals. DMSO given during the rapid deposition period rapidly abolished the high SAA levels and maintained it at a level seen in normal animals. Both colchicine and DMSO therapy, if instituted after the rapid amyloid deposition period, failed to reduce SAA levels significantly below that of untreated controls.