Administration of neutralizing antibody against rabbit IL-1 receptor antagonist exacerbates lipopolysaccharide-induced arthritis in rabbits.
Endogenous IL-1 receptor antagonist (IL-1ra) may down-regulate part of IL-1 actions. We examined the participation of endogenous IL-1ra in the production of IL-1 beta in vitro. Macrophages cultured on adherent IgG produced a 100-fold molar excess of IL-1ra, compared with IL-1 beta. In the presence of a neutralizing monoclonal antibody (mAb) against rabbit IL-1ra, the production of antigenic IL-1 beta increased by 20-60%. Since the molar ratio of IL-1ra over IL-1 was 160- to 400-fold in synovial fluid (SF) of lipopolysaccharide (LPS)-induced arthritis, we examined the functional role of endogenous IL-1ra in the regulation of inflammatory responses. When measured in the presence of anti-IL-1ra mAb, masked IL-1 activity in SF became evident, with a 3- to 4-fold increment. The administration of anti-IL-1ra mAb with LPS into rabbit knee joints increased the IL-1 activity 4-fold and the production of antigenic IL-1 beta by 30-50%. The treatment also enhanced by 20-40% LPS-induced leukocyte infiltration and protein leakage. Therefore, endogenous IL-1ra apparently acts as a down-regulating factor for limiting deleterious effects of IL-1 by masking the biological activity and by inhibiting the production.
Fukumoto
T
T
Department of Pathology, Kumamoto University School of Medicine, Japan.
Matsukawa
A
A
Ohkawara
S
S
Takagi
K
K
Yoshinaga
M
M
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D001168:Arthritis / Q000209:etiology*; D005260:Female; D007140:Immunoglobulin Fab Fragments / Q000494:pharmacology*; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000633:toxicity*; D008264:Macrophages / Q000378:metabolism; D011817:Rabbits; D012795:Sialoglycoproteins / Q000502:physiology*
D000911:Antibodies, Monoclonal; D007140:Immunoglobulin Fab Fragments; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D008070:Lipopolysaccharides; D012795:Sialoglycoproteins