Antibodies in plasma

Immunogenicity can be identified by identifying potential antibodies in plasma. These usually involve ELISA methods. T-cell-dependent antibody responses can be evaluated, and plaque assays involving IgM antibody responses are available. 

About 70% of patients also have antiintrinsic factor antibodies in plasma, saliva, and gastric juice. These canbe either blocking antibodies, which prevent the binding of vitamin B12 to intrinsic factor, or precipitating antibodies, which precipitate both free intrinsic factor and intrinsic factor-vitamin B12 complex. Some patients have both types of antiintrinsic factor antibody. Although the oral administration of partially purified preparations of intrinsic factor will restore the absorption of vitamin B12 in many patients withpernicious anemia, this can eventually result in the production of antiintrinsic factor antibodies, so parenteral administration of vitamin B12 is the preferred means of treatment. 

Geno- type Phenotype Blood group antigens on red cells (minimal determinant structure) Antibodies in plasma Giycosyitransferases in plasma... 

The use of one or more assay methods should be addressed on a case-by-case basis and the scientific rationale should be provided. One validated method is usually considered sufficient. For example, quantitation of TCA-precipitable radioactivity following administration of a radiolabeled protein may provide adequate information, but a specific assay for the analyte is preferred. Ideally the assay methods should be the same for animals and humans. The possible influence of plasma binding proteins and/or antibodies in plasma/ serum on the assay performance should be determined. 

The fundamental role of blood in the maintenance of homeostasis and the ease with which blood can be obtained have meant that the study of its constituents has been of central importance in the development of biochemistry and clinical biochemistry. The basic properties of a number of plasma proteins, including the immunoglobulins (antibodies), are described in this chapter. Changes in the amounts of various plasma proteins and immunoglobulins occur in many diseases and can be monitored by electrophoresis or other suitable procedures. As indicated in an earlier chapter, alterations of the activities of certain enzymes found in plasma are of diagnostic use in a number of pathologic conditions. 

The preparation of antibodies specific for the individual plasma proteins has greatly facilitated their smdy, allowing the precipitation and isolation of pure proteins from the complex mixmre present in tissues or plasma. In addition, the use of isotopes has made possible the determination of their pathways of biosynthesis and of their turnover rates in plasma. 

Immunologic abnormahties (eg, transfusion reactions, the presence in plasma of warm and cold antibodies that lyse red blood cells, and unusual sensitivity to complement) also fall in this class, as do toxins released by various infectious agents, such as certain bacteria (eg, Clostridium). Some snakes release venoms that act to lyse the red cell membrane (eg, via the action of phospholipases or proteinases). 

Somatic hypermutation High frequency of mutation that occurs in the gene segments encoding the variable regions of antibodies during the differentiation of B lymphocytes into antibody-producing plasma cells. 

Immunoglobulins are purified from the serum (or plasma) of human donors by methods similar to those used to purify animal-derived antibodies. In most instances, the immunoglobulin preparations are enriched in antibodies capable of binding to a specific antigen (usually an infectious mi-croorganism/virus). These may be purified from donated blood of individuals who have recently ... 

Enzyme-Linked Immunosorbent Assay (ELISA) An immunological technique used to quantify the amount of antigen or antibody in a sample such as blood plasma or serum. 

Part—VI has been solely devoted to Miscellaneous Assay Methods wherein radioimmunoassay (RIA) (Chapter 32) has been discussed extensively. Various arms of theoretical aspects viz., hapten determinants and purity importance of antigenic determinants and analysis of competitive antibody binding of isotopically labeled compounds. The applications of RIA in pharmaceutical analysis, such as morphine, hydromorphone and hydrocordone in human plasma clonazepam, flurazepam in human plasma chlordiazepoxide in plasma barbiturates, flunisolide in human plasma have been described elaborately. Lastly, the novel applications of RIA-techniques, combined RIA-technique-isotope dilution and stereospecificity have also been included to highlight the importance of RIA in the analytical armamentarium. 

Immunoassay as an analytical technique was introduced by Rosalind Yalow and Solomon Berson in 1960 with their use of anti-insulin antibodies to measure the concentration of the hormone in plasma. This advance, for which Rosalind Yalow was awarded the Nobel prize, was probably the most important single advance in biological measurement of the following two decades. Examples of the use of immunoassay may now be found in almost all areas of analytical biochemistry. 

Hybridoma Cell produced by the fusion of antibody-producing plasma cells with myeloma/carcinoma cells. The resultant hybrids have then the capacity to produce antibody (as determined by the properties of the plasma cells), and can be grown in continuous culture indefinitely owing to the immortality of the myeloma fusion partner. This technique enabled the first continuous supply of monoclonal antibodies to be produced. 

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