Calcium-dependent and calcium-independent signals in the conglutinin-binding assay (KgBa) for immune complexes. Influence of anti-collagen-antibodies

Chlamydia pneumoniae-specific serum immune complexes in patients with multiple sclerosis

The significance of Chlamydia pneumoniae infection in patients with multiple sclerosis (MS) is unclear. We determined the frequency of serum C. pneumoniae-specific immune complexes in patients with MS, neurological (OND) and healthy controls in a blinded, cross-sectional study. C. pneumoniae immune complexes were detected in 24% (38/156) of MS patients, 16% (11/69) of OND and 15% (77/499) of healthy controls. The odds ratio for all MS patients was 3.95 (95% CI: 2.15 to 7.24; P < 0.0001) accounting for the covariates: sex, age, socio-economic status and area of residence. The odds ratio for recently diagnosed MS patients was 4.33 (95% CI: 1.76 to 10.64; P = 0.001). Systemic C. pneumoniae infection is more frequent in MS patients than the healthy population and occurs early in the course of the disease. Multiple Sclerosis 2007; 14: 292—299. http://msj.sagepub.com

Allosteric regulation by calcium of rabbit polyclonal anti-cyclic GMP antibody

Calcium increased the binding of rabbit polyclonal antibodies and cGMP by increasing antibody affinity without altering the number of binding sites (Bmax). Competitive binding studies revealed that calcium increased the affinity of antibody for cGMP derivatives similarly, suggesting that the effects of this cation were antigen-independent. Kinetic binding studies demonstrated that calcium increased affinity by decreasing the dissociation rate without altering the association rate of antigen and antibody. Studies of the dissociation of antigen-antibody complexes preformed in the absence of calcium suggested that this cation regulated antibody function allosterically. These data contrast with those obtained previously suggesting that calcium regulated the interaction of cAMP and antibodies by increasing Bmax without altering affinity by reaction coupling. Re-analysis of those data demonstrated that calcium increased the affinity without altering the number of binding sites of antibodies to cAMP, in close agreement with the present results. These data suggest that allosteric modulation of antibody function by calcium may be a general mechanism regulating the interaction of polyclonal antibodies with cyclic nucleotides.

Difference and ratio plots: simple tools for improved presentation and interpretation of scientific data. Unexpected possibilities for the use of the conglutinin binding assay in inflammatory rheumatic diseases

11111onglutinin-binding assay (KgBa) has gained widespread use for the detection of circulating immune complexes. A recent paper questioned the interpretation of the results obtained by this method and the validity of the assay (Holmskov et al. (1992) J. Immunol. Methods 148, 225). We now present hitherto unnoted differences between controls and patients with either rheumatoid arthritis or systemic lupus erythematosus. For this we use simple, but unconventional, graphic representations of the data, based on difference plots and ratio plots. Differences between patients with Burkitt's lymphoma and systemic lupus erythematosus from another previously published study (Macanovic, M. and Lachmann, P.J. (1979) Clin. Exp. Immunol. 38, 274) are also represented using ratio plots. Our observations indicate that analysis by regression analysis may often be misleading.