Immune complexes and complement catabolism in ankylosing spondylitis

Abstract

In serum samples from 37 patients with ankylosing spondylitis (AS), immune complexes were quantitated by the 125I-Clq binding test; in paired plasma samples the C3 breakdown product C3d was measured by an immunochemical method. Compared to results in 30 blood donors, the Clq binding activity was significantly (greater than 2 SD), although discretely, increased in 5 of 8 patients with seropositive AS, but not in other AS patients. All C3d levels were within the normal range. In a parallel investigation, increased Clq binding activity and C3d levels were found in 87% and 90%, respectively, of patients with seropositive rheumatoid arthritis.

The proteins of the aqueous humour

“…Then, it may be asked whether the uveitis which occurs in patients with diseases associated with immune complexes in serum, is not due to the intraocular deposition of these complexes. These diseases are, for example, ankylosing spondylitis (Gabay et al, 1977), sarcoidosis (Hedfors and Norberg, 1974), Behqet's syndrome (Williams and Lehner, 1977;Gupta et al, 1978;Gamble et al, 1979) and Crohn's disease (Doe et al, 1973;Jewell and MacLennan, 1973).…”

The in-vivo metabolism of C3 in ankylosing spondylitis.

“…Most studies have shown an increase of C3 and C4 levels, while the evidence for activation of complement as studied by the presence of C3 or C4 conversion products is controversial. 6 We present the results of metabolic studies in AS patients and controls performed with purified radiolabelled C3. This factor has a central position in the complement system, as it is activated both by the classical and by the alternative pathways.7…”

Ankylosing Spondylitis and Glomerulonephritis

“…Recent reports [11][12][13] indicates that in seronegative spondyloarthritis, circulating immune complexes were pres ent, and that they can be correlated with the activity of the disease [II]. In our patient a large size (19S) circulating immune complex material was detected, and this size complex is known to produce experimentally, immune complex disease [14,15].…”