Immune precipitation reactions

Chuang further cautions that In solid phase immunoassay, it is generally assumed that antigens adsorbed to a surface, such as polystyrene microtiter dishes, will react with specific antibody in a manner similar to that antigen-antibody reaction in solutions such as occur in immune precipitation. However, our evidence and others89) seem to point out that data obtained from solid phase immunoassays should be interpreted with caution since adsorption of a nonantigen to a polymer surface could render it immunoreactive to previously unreactive antibodies. ... 

Initially a qualitative test, then a semiquantitative and, if deemed useful, a quantitative estimation of antibody can be performed.The table presents the sensitivity of some of the in vitro serological tests that can be used. (The advantages and disadvantages of the different techniques will be discussed by other authors.) When detecting immune responses in different species, one should reckon with the fact that not all antibody systems lead to a precipitation reaction. Rabbit sera containing precipitating... 

An interesting alternative to NMR investigations for the assignment of the configuration of the cyclic acetal of pyruvated polysaccharides uses quantitative inhibition of specific immune precipitation techniques [25]. Thus, synthetic (R) and (S) 4,6-pyruvated methyl galactosides were applied as inhibitors for the precipitation reaction of Klebsiella polysaccharides with the respective antisera. The (R) isomer was revealed to be a potent inhibitor, and thus proved the K. serotype Kll and K21 polysaccharides to contain 4,6-0-[(R)-l-carboxy-ethylidene]-galactopyranosyl residues. 

Another antibody was experimentally produced in rabbits by injecting pepsin (G5). It was detected by the Ouchterlony technique and precipitation reactions, and may have some clinical significance in producing atrophy of chief cells. Repeated injection of this immune serum into rats also caused decrease in the volume of gastric juice, with lower concentrations of acid and pepsin. The controls injected with antibodies to egg albumin, nonspecific globulins, and saline did not show similar changes (see Fig. ). 

HeUsing K. Immune reactions in polysaccharide media Polysaccharide-enhanced precipitation reactions with antigens of various sizes. Biochem J 1969 114 145-9. 

The strong cross-reaction of the polysaccharide of Aloe vera, - which contains D-mannose, D-glucose, and a small proportion of galactose and a pentose, could also be attributed to the presence of multiple residues of d-glucose, since the gum recovered from the immune precipitate contained no galactose. A portion of the D-glucose in Aloe vera is (l->4)-linked and would account for the observed cross-reaction. 

Techniques for the detection or assay of various substances based on the reaction of those substances with specific antibodies (or vice versa, i.e. the detection and assay of antibodies using antigens). Such techniques include agglutination reactions, automated immune precipitation, complement fixation tests, crossed electrophoresis, counter electrophoresis, double diffusion, enzyme immunoassay, fluoroimmunoassay, haem-agglutination, immunoelectrophoresis, immunofluoresence, radial immunodiffusion, spin immunoassay, immunofixation, immunoradiometric assay and radioimmunoassay. See separate entries for these subjects. 

Turbidimetry can be used for the measurement of plasma proteins by their reaction with antisera to form light scattering immune precipitates. Many qualitative and semi quantitative tests are also used in clinical chemistry, e.g. the flocculation tests. 

Because of the complexity of bioassays, the expenses for animals and facilities, and ethical considerations, many investigators have sought in vitro methods for detection and quantitation of botulism toxins and antitoxins. One of the earliest was the Ramon flocculation test (57), in which the reaction between a toxin and its homologous antitoxin standard was visualized by a precipitation reaction. This was advantageous in vaccine production because the toxoid, which cannot be measured by bioassay can be quantitated in a comparable manner as the toxin by this test. The flocculation unit (Lf) was used as the antigenic unit employed in the formulation of botulism toxoids used for human immunization (7). 

The formation of acids from heteroatoms creates a corrosion problem. At the working temperatures, stainless steels are easily corroded by the acids. Even platinum and gold are not immune to corrosion. One solution is to add sodium hydroxide to the reactant mixture to neutralize the acids as they form. However, because the dielectric constant of water is low at the temperatures and pressure in use, the salts formed have low solubiHty at the supercritical temperatures and tend to precipitate and plug reaction tubes. Most hydrothermal processing is oxidation, and has been called supercritical water oxidation. 

Edwards and Jones (31) identified the condensed tannin extracted from cotton plant bracts as a tannin-like polymer of 5, 7, 3, 4 tetrahydroxyflaven 3-4 diol (THF). They demonstrated nonspecific precipitation with IgG, IgM, IgA, five myeloma IgG s and positive gel diffusion reactions with heavy and light chains. Fab and Fc pieces of IgG. Nevertheless, they refuted this reaction as a true antigen-antibody reaction, and subsequently suggested that byssinosis was not an immune complex mediated pulmonary disease. 

Type 3, immune complex vasculitis (serum sickness, Arthus reaction). Drug-antibody complexes precipitate on vascular walls, complement is activated, and an inflammatory reaction is triggered. Attracted neutrophils, in a futile attempt to phagocytose the complexes, liberate lysosomal enzymes that damage the vascular walls (inflammation, vasculitis). Symptoms may include fever, exanthema swelling of lymph nodes, arthritis, nephritis, and neuropathy. 

Anaphylactic and serum sickness reactions to ALG and murine monoclonal antibodies have been observed and usually require cessation of therapy. Complexes of host antibodies with horse ALG may precipitate and localize in the glomeruli of the kidneys. Even more disturbing has been the development of histiocytic lymphomas in the buttock at the site of ALG injection. The incidence of lymphoma as well as other forms of cancer is increased in kidney transplant patients. It appears likely that part of the increased risk of cancer is related to the suppression of a normally potent defense system against oncogenic viruses or transformed cells. The preponderance of lymphoma in these cancer cases is thought to be related to the concurrence of chronic immune suppression with chronic low-level lymphocyte proliferation. 

The bleeding potential is similar among the agents. However, thrombocytopenia, particularly profound thrombocytopenia (platelet count <50,000 mrrT3) occurs with a two-to four-fold higher frequency with abciximab (0.4— 1.0%) compared with eptifibatide (0-0.2%) or tirofiban (0,1 —0.3%) (6), The exact mechanism of this difference is not clear, However, immune complex-mediated reaction (due to an anamnestic response to the humanized chimeric antibody) may contribute to rapid precipitation of thrombocytopenia with abciximab (6), Platelet counts should, therefore, be measured early (within the first one to four hours) after administration of these agents and followed for the duration of therapy. Platelet transfusion should be considered for profound thrombocytopenia with or without serious bleeding (6). 

Forerunners of nonisotopic immunoassay had already appeared before radioimmunoassay was developed. For example, nephelometry is based on precipitation, which is known as the classical immune reaction, and the ideas of particle immunoassay and viroimmunoassay seem to have developed from the hemagglutination test. The principles of enzyme and fluorescence immunoassay had already been used as enzyme and fluorescence antibody techniques in histochemical analysis. In 1971, two groups reported use of an enzyme immunoassay (E5, V2). Leute et al. reported spin immunoassay, which has spurred recent development of nonisotopic immunoassays (L5). 

Monoclonal antibodies, regardless of whether they are of high or low affinity, do not form a lattice with antigen, and, hence only rarely form insoluble precipitates. However, in immunohistochemistry, the capability of a primary antibody to form precipitating immune complexes is of little importance because reaction with immobilized tissue antigen entails antibody capture onto tissue rather than precipitation. 

Titration methods of following reactions are not always immune either. A precipitate formed during the titration may introduce a completely unsuspected catalytic effect, as the following example illustrates. In a study of the rate of the Menschutkin reaction... 

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