A simple hemolytic assay for bovine complement component C3

Toxicity of complement for chondrocytes. A possible source of cartilage degradation in inflammatory arthritis

Cartilage from patients with rheumatoid arthritis and from animals with antigen-induced arthritis is frequently contaminated with complement-containing immune complexes. A possible role for complement activation in cartilage degradation was modeled in vitro by exposing cultured bovine chondrocytes to homologous serum, and determining cytotoxicity by monitoring the release of intracellular 51Cr. Complement activation was found to be cytotoxic, having maximal effect at 20-30% serum by 18 h. Serum toxicity was ablated by heat (50 degrees C, 20 min) or methylamine treatment but not by EGTA, suggesting that in these experiments activation occurred by the alternate route. The implications of the results are discussed in relation to ultrastructural evidence for the involvement of complement in the pathogenesis of cartilage degradation in inflammatory arthritis.

Studies on activation and levels of haemolytic complement of buffalo (Bubalus bubalis). III. C3 haemolytic activity in health and chronic disease

Estimation of haemolytic complement component C3 activity in serum was done by using buffalo serum functionally depleted of C3, with methylamine. In the one-step alternate pathway (AP) haemolytic assay, C3 activity in the serum was estimated by its capacity to reconstitute the AP haemolytic activity in C3 depleted serum. Levels of haemolytic C3 were determined in the sera of 70 apparently healthy buffaloes and of seven diseased buffaloes of which five were suffering from Johne's disease (JD) and two from JD and tuberculosis (TB). The haemolytic C3 levels in healthy animals varied with age, reaching peak values in the 2.5-3-year-old, declining after 4 years of age. The C3 levels in buffaloes suffering from chronic diseases was significantly higher (P < 0.05) than the levels in healthy buffaloes of the same age group.

Determination of optimal in vitro conditions for caprine alternative complement pathway assay

Optimal in vitro testing conditions for caprine alternative complement pathway assay were determined. Effects of the following variables were tested: heterologous erythrocytes; pH, ionic strength and Mg2+ ion concentration of the complement diluent; incubation time and temperature. Rabbit erythrocytes were the optimal target cells. The optimal buffer conditions were: pH 8.0, ionic strength 0.06 mmol NaCl and 5mmol Mg2+ ion. Optimal incubation time and temperature were 75 min and 30 degrees C, respectively.

Isolation of the fifth component of the bovine complement system

Bovine C5 has been isolated from fresh bovine serum by a five-step procedure: polyethylene glycol precipitation, sequential ion-exchange chromatography on DEAE-Sephacel and CM-Sephadex, hydroxylapatite chromatography, and affinity chromatography. The purified C5 was a protein of apparent molecular weight 202,000 +/- 9,000 composed of two chains: an alpha-chain of molecular weight 127,000 +/- 5,000 and a beta-chain of molecular weight 74,000 +/- 2,000. The alpha-chain was cleaved by Sepharose-CVF.Bb (a cobra venom factor (CVF)-induced C3/C5 alternative pathway convertase) in the absence of any C3 or C3b. The monocarboxylic acid form of K-76, a sesquiterpene compound isolated from the culture filtrates of Stachybotris complementi, inhibited the alternative pathway of bovine serum, and the inhibited hemolytic activity was restored, in a dose dependent manner, by bovine C5. This provided the basis for a C5 functional assay throughout the purification procedure. The purified C5 showed species specificity and was functionally distinct from bovine C3.

A simple isolation procedure for functionally pure components of the bovine alternative complement pathway (ACP) C3 convertase and bovine conglutinin (K)

A simple multicomponent isolation procedure for bovine C3, factor B, factor D and conglutinin (K) from a single serum sample is described. The components of the alternative pathway C3 convertase were isolated in milligram quantities from 800 ml bovine serum and were found to be functionally pure with respect to each other and to factors H and I.