Measurement of the chemotactic complement fragment C5a in rheumatoid synovial fluids by radioimmunoassay: role of C5a in the acute inflammatory phase.
Evidence suggests that complement is activated in rheumatoid joints. A sensitive radioimmunoassay for the activation fragment of C5, C5a, which is a potent chemoattractant for neutrophils, was therefore developed. A mean C5a concentration in 22 rheumatoid joint fluids of about 2.5 x 10(-9) mol/l was found. This concentration of C5a is sufficient to induce two of the characteristic features of the acute inflammatory phases of rheumatoid arthritis: neutrophil accumulation and microvascular plasma protein leakage. In animal models it has been shown that C5a is a potent inducer of inflammatory oedema by a neutrophil dependent mechanism. A striking feature of the acute inflammatory phases of rheumatoid arthritis is the appearance of high numbers of neutrophils in the synovial fluid. It is suggested that C5a might have a role in mediating neutrophil accumulation and, as a consequence, may be important in acute joint swelling and pain.
Jose
P J
PJ
Section of Vascular Biology, MRC Clinical Research Centre, Harrow, Middlesex.
Moss
I K
IK
Maini
R N
RN
Williams
T J
TJ
D000328:Adult; D000368:Aged; D016918:Arthritis, Reactive / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D003167:Complement Activation; D015926:Complement C3a / Q000032:analysis; D015936:Complement C5a / Q000032:analysis*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods; D013582:Synovial Fluid / Q000276:immunology*
D015926:Complement C3a; D015936:Complement C5a