Cells of the mononuclear phagocytic system (MPS) were described as playing a decisive role in amyloidogenesis. A relationship between the
amyloid enhancing factor (AEF) and MPS cells was suggested and recently
AEF activity was attributed to a
serine esterase (SE) of leucocytic origin. In the present study, no correlation was found between the SE content and
AEF activity in either peritoneal cell lysates or
AEF preparations of different origin. Furthermore, pretreatment of fibril
AEF (FAEF) with the SE inhibitor phenylmethylsulphonyl
fluoride (PMSF) did not affect its activity in the hamster. Blockade of the MPS by
dextran sulphate did not inhibit deposition of
amyloid after
intravenous injection of FAEF but
amyloid deposition was inhibited when FAEF was administered intraperitoneally. These results suggest that MPS cells could be involved in transport of
AEF, but that phagocytic activity of MPS cells is not essential in AA-
amyloid fibrillogenesis. It is concluded that these results are not consistent with the previously suggested nature of the
AEF or with the proposed central role of the MPS in amyloidogenesis.