Raised circulating interleukin-18 levels in reactive AA-amyloidosis.
OBJECTIVE
To study the circulating levels of interleukin-18 (IL-18), a proinflammtory cytokine implicated in the T helper I response, in patients with rheumatoid arthrtitis (RA) with or without amyloidosis.


METHODS
Plasma IL-18 levels were studied by enzyme-linked immusorbent assay in 55 RA patients with reactive amyloidosis and in 55 RA patients without amyloidosis matched with respect to age, sex, seropositivity, disease duration and inflammatory activity, as well as in 55 healthy control subjects.


RESULTS
Plasma IL-18 levels were significantly elevated in RA patients as compared with control subjects. Those RA patients who had amyloid had significantly higher circulating level of IL-18 than those without amyloid (418.1 +/- 32.1 ng/l versus 317.0 +/- 21.3 ng/l, P<0.02). This difference was not due to differences in inflammatory activity, nor was it related to renalfunction.


CONCLUSIONS
RA is associated with increased levels of plasma IL-18, the levels being significantly higher in patients with amyloid than in those without amyloid The increased level in the amyloidosis patients may reflect the interaction ofamyloid with cellular meatbolic pathways or, possibly, suggest a direct role of IL-18 in amyloidogenesis.
Maury
C P J
CP
Department of Medicine, University of Helsinki, Finland. Peter.Maury@hus.fi
Tiitinen
S
S
Laiho
K
K
Kaarela
K
K
Liljeström
M
M
D000682:Amyloid / Q000378:metabolism; D000686:Amyloidosis / Q000378:metabolism* / Q000473:pathology; D001172:Arthritis, Rheumatoid / Q000097:blood*; D002097:C-Reactive Protein / Q000378:metabolism; D016022:Case-Control Studies; D003404:Creatinine / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D049669:History, 16th Century; D006801:Humans; D020382:Interleukin-18 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D000685:Serum Amyloid A Protein / Q000378:metabolism*; D018417:Th1 Cells / Q000276:immunology; D015854:Up-Regulation
D000682:Amyloid; D020382:Interleukin-18; D000685:Serum Amyloid A Protein; D002097:C-Reactive Protein; D003404:Creatinine