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PubMedDate not supplied

[Some patterns in formation of antibody-antigen-antibody complexes on a solid phase: experimental study and mathematical modeling].

Equilibrium and kinetic constants were determined for interactions between alpha-amylase from Bacillus subtilis and polyclonal antibodies (with immobilization of either reagent). The effects of desorption of immobilized molecules and intermolecular complexes on the immunochemical reaction were studied. Models of sandwich enzyme immunoassay, whereby complexes of immobilized antibody-determined antigen-labeled antibody were formed, were developed from these results. The results obtained from the model and experiments were compared. The desorption was shown to cause the hook-effect, that is, a decrease in the label binding at high concentrations of the antigen.

Antigen-Antibody Complex↗
PubMed1994

Purification of antibody-antigen complexes containing recombinant SIV proteins: comparison of antigen and antibody-antigen complexes for immune priming.

This paper describes a general procedure for the two-step purification of recombinant proteins as antibody-antigen complexes in which there is no uncomplexed antibody or antigen. In this way, immune complexes containing the p17, p27, vpr and vpx proteins of simian immunodeficiency virus (SIV) have been purified. Antibody-antigen complexes are more immunogenic than antigen when administered either alone or with alum. The significance of the work is that this general method could be modified for the manufacture of immune complexes for incorporation into multivalent vaccines.

Animals↗
PubMed1976

Intestinal uptake of macromolecules. V. Comparison of the in vitro uptake by rat small intestine of antigen-antibody complexes prepared in antibody or antigen excess.

The in vitro absorption by rat jejunal and ileal gut sacs of soluble antigen-antibody complexes and of antigen alone was compared. Complexes prepared in 2-fold antibody excess were absorbed in significantly smaller quantities than was antigen alone. Complexes prepared in 50-fold antigen excess were absorbed by jejunal gut sacs in quantities equivalent to that antigen alone, whereas the absorption of such complexes by ileal sacs was somewhat decreased compared to that of antigen. There was less radiolabeled antigen tightly bound to the intestinal mucosa of gut sacs exposed to complexes prepared in antigen or antibody excess compared to antigen alone. Complexes prepared in antibody excess appeared to stimulate secretion of mucus and complexes were associated with the mucus fraction. It was suggested that the large size of complexes prepared in antibody excess may result in their trapping in the mucus coat of the gut, thereby preventing contact with the surface of the enterocyte from whence uptake by pinocytosis is initiated. In addition, complexes appear to be shed from the surface with mucus by a mechanism still to be elucidated.

Animals↗
PubMed1969

Virus-like antigen, antibody, and antigen-antibody complexes in hepatitis measured by complement fixation.

Complement fixation techniques are described for measuring a virus-like antigen associated with viral hepatitis. Antigen was found in the blood of 98 percent of 130 patients, with the serum form of hepatitis, from whom multiple samples were obtained. Antibodies arising during hepatitis are usually combined with antigen and cause anticomplementary activity in the serum, which is reversible with excess antigen or antibody. Tests for antigen and specific anticomplementary activity can be used diagnostically and to screen blood donors for hepatitis carriers.

Antigen-Antibody Reactions↗
PubMed1977

Thermodynamics of antibody-antigen reactions. 2. The binding of bivalent synthetic random coil antigens to antibodies having different antigen precipitating properties.

The objects of this study were the equine IgG and IgG(T) classes of antibodies with immunologic specificity for the dinitrophenyl group and bivalent antigens consisting of linear poly(ethylene glycol) polymers which terminated at both ends in dinitrophenyl groups. Complex formation between antibodies of both classes and one of several sharp fractions of antigen having number average molecular weights in the range 25 000 to 75 000 were studied by measuring the light scattered from solutions containing equimolar amounts (approximately 5 x 10(-6) mol/L) of one of the antibodies and one size fraction of antigen, and variable amounts of monovalent hapten. The data were analyzed in the context of a model that accounted for the formation of linear and cyclic complexes of all extents of aggregation. Two parameters in addition to the intrinsic antibody-dinitrophenyl group association constant were found to be necessary in the assumed equilibrium model to account for the behavior of the system. One of these accounted for the looses in configuration entropy that resulted when a random-coil polymer became bound at one end to a space-occupying antibody. The other was a ring closure factor for the formation of cyclic complexes. Ring closure factors for the formation of larger cyclic complexes (present in only small amounts under the conditions studied) were related to the ring closure factor for the formation of the smallest, which was found to increase as antigen size decreased, and for each antigen size to be consistently higher for IgG(T) antibody than for IgG antibody. Comparison of the theoretically estimated values of the two parameters within their measured values indicated that the average conformation of IgG antibodies in solution is open ("T" shaped) but the average inter-Fab are angle in IgG(T) antibodies is approximately 60 degrees or less.

Animals↗
PubMed1977

Effects of ionic and nonionic detergents on antigen-antibody reactions.

Using highly sensitive and quantitative radioimmunoassay procedures we have measured the effects of different concentrations of three commonly used detergents, SDS, DOC, and Triton X-100, on antibody-antigen reactions. Triton X-100, had a relatively mild effect on primary antigen-antibody bindings, the precipitin reaction, and a double antibody RIA as evidenced by only an 8 to 10% inhibition of binding or precipitation. These results were not detergent concentration dependent, as Triton concentrations ranging from 5 to 0.1% had virtually no differential effects. Sodium deoxycholate (DOC) had a more profound effect on both primary antigen-antibody binding and the precipitin reaction than did Triton X-100, and its effects, unlike those of Triton X-100, were concentration dependent. There was a direct relationship between concentration of DOC and degree of inhibition of both primary binding and immune precepitation especially in antigen excess. Sodium dodecylsulfate (SDS), at concentrations 10- to 100-fold less than either Triton X-100 or DOC, had profound inhibitory effects on primary antigen-antibody binding, the precipitin reaction, and a double antibody radioimmunoassay. Generally, at concentrations greater that 0.01% SDS, almost all immunochemical reactivity is destroyed.

Animals↗
PubMed2001

Fast selection of antibodies without antigen purification: adaptation of the protein fragment complementation assay to select antigen-antibody pairs.

We have adapted the protein fragment complementation assay (PCA) to the screening and selection of antibodies in the single-chain Fv (scFv) format. In this assay, two interacting proteins (target and antibody) are genetically fused to the two halves of the dissected enzyme dihydrofolate reductase. Binding of the two partners reassembles this enzyme and reconstitutes its activity, thus allowing growth on minimal medium. We have optimized this system with regard to linker length and orientation, and can reach an efficiency for antigen/antibody interactions similar to that with fused leucine zippers. Using several model antibodies specific for peptides and proteins, we show that cognate interactions give rise to about seven orders of magnitude more colonies than non-specific interactions. When transforming mixtures of plasmids encoding different antigens and/or antibodies, all colonies tested contained plasmids encoding cognate pairs. We believe that this system will be very powerful as a routine system for generating antibodies, especially in functional genomics, since it does not require purification and immobilization of the antigen. The identification of an antibody specific for a cDNA or EST-encoded protein will require only cloning, transformation and plating of bacteria.

Animals↗
PubMed1982

Experimental antigen-antibody complex disease in mice. The role of antibody levels, antibody affinity and circulating antigen-antibody complexes.

Chronic antigen-antibody complex disease (A-ACD) was induced in mice by daily injections of HSA. The disease was characterized by death, intense glomerular basement membrane deposition of complexes in the kidneys, proteinuria and an impairment of the glomerular filtration rate. In mice that had been selectively bred to produce antibody of low affinity to protein antigens injected in saline, the incidence of chronic A-ACD was 61% compared to 21% in mice selectively bred to produce antibody of high affinity. Low affinity female mice produced approximately ten times as much free antibody to HSA as did low affinity males and high affinity males and females, but this did not result in an increase incidence of chronic A-ACD in low affinity female mice. Low affinity female mice also had the highest levels of circulating antigen-antibody complexes detected by conglutinin and Clq binding assays, but there was no correlation between the presence of high levels of complexes in serum and tissue damage. In both lines of mice the mean affinity of free antibody to HSA started low and increased with time and the number of injections of antigen. However, development of chronic A-ACD in individual low affinity mice appeared to be associated with a failure to produce this time-associated increase in antibody affinity. These results are discussed with reference to the relevance of the measurement of the amount of affinity of free antibody in serum and the levels of circulating antigen-antibody complexes to the production of tissue damage in this model of chronic A-ACD.

Animals↗
PubMed1986

Cross-blot and cross-dot system: a high-performance system for the detection of antigen-antibody complexes on nitrocellulose.

We present a reliable, simple, and quick system for screening antibody-antigen complexes on nitrocellulose. The apparatus necessary for this system is inexpensive and easy to use, and it can be adapted to blot or dot analysis without any modification. The number of antibody-antigen combinations that can be tested in one experiment ranges from 25 to 31 for blot analysis and from 345 to 600 for dot analysis. This system also offers numerous experimental advantages: it makes it possible to estimate with only one experiment the contribution of the different reaction stages to background noise and so allows unambiguous interpretation of the antibody-antigen reaction. Furthermore, this system can be used for any hybridization experiment on nitrocellulose.

Animals↗