Extremely active murine amyloid enhancing factor.
OBJECTIVE: To generate and characterize a highly active amyloid enhancing factor (AEF). METHODS: AEF was obtained from amyloidotic and pre-amyloidotic mice spleens that were homogenized in 50% acetone in H2O. The grade of AEF enhancing activity was studied in relation to the procedure used to generate the AEF, the amount of AEF administered, the duration of amyloid induction and the effect of solvent and denaturing agents. RESULTS: Both priming of the splenic source of the AEF with an amyloidogen and acetone processing were essential for the AEF activity. AEF in a single intravenous dose as low as 1 nanogram per mouse induced amyloidosis in mice within 2-6 days. Polyacrylamide gel electrophoresis of the AEF showed two protein bands of molecular weight (MW) 9-11 KD not present in normal spleen homogenates. Dialysis of the AEF showed that the active components can pass through a dialysis bag with an MW cutoff of 12 KD. CONCLUSIONS: These findings suggest that ours is the most active AEF currently available and that it has active constituents of low MW ( < or = 12 KD) which appear in the spleen during amyloidogenesis.