Amyloid enhancing factor (AEF) in the aging mouse.

Amyloid enhancing factor (AEF) activity was tested in spleen homogenates from 52, 28, and 9-week-old untreated mice. Strong AEF activity was present in the supernatant of spleen homogenate from the 52-week-old mice. Only weak activity was observed in the supernatant from the 28-week-old mice, and none was seen in that from the 9-week-old mice. Crude spleen homogenates from the 52-week-old mice were subjected to Sephacryl S-300 gel filtration. AEF activity existed in the first gel filtration peak. These findings suggest that AEF increases in the spleens of aged mice and that AEF may be a substance of high molecular weight.