Soluble antigens

Use of inappropriate fixative. Use of certain fixatives may damage or destroy antigens or epitopes in the tissue specimen. Use of non-cross linking fixatives may allow the elution of antigens soluble in IHC reagents. Check manufacturer s specifications regarding recommended fixative. 29-33... 

Kernebeck T, Lohse A, Grotzinger J. A bioinformatical approach suggests the function of the autoimmune hepatitis target antigen soluble liver antigen/liver pancreas. Hepatology 2001 34 230-3. 

Fernie BF, Poli G, Fauci AS (1991) Alpha interferon suppresses virion but not soluble human immunodeficiency virus antigen production in chronically infected T-lymphocytic cells. J Virol 65 3968-3971... 

The number of different proteins in a membrane varies from less than a dozen in the sarcoplasmic reticulum to over 100 in the plasma membrane. Most membrane proteins can be separated from one another using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), a technique that has revolutionized their study. In the absence of SDS, few membrane proteins would remain soluble during electrophoresis. Proteins are the major functional molecules of membranes and consist of enzymes, pumps and channels, structural components, antigens (eg, for histocompatibility), and receptors for various molecules. Because every membrane possesses a different complement of proteins, there is no such thing as a typical membrane structure. The enzymatic properties of several different membranes are shown in Table 41-2. 

If antigen, released firm the infective agent, is soluble then antigen-antibody complexes are produced. When antibody is present at a concentration eqnal to or greater... 

Antibody molecules are bivalent whilst antigens can be multivalent. The resultant combination may result in either small, soluble complexes, or large insoluble aggre tes, depending on the nature of the two molecules in the system. The following are examples of the reactions that can occur. 

Precipitation. The formation of insoluble precipitates which enable the phagocytes to eliminate soluble antigen firm the body. 

This may oeeur by the production of cytokines with inhibitory funetion the ability to absorb neeessary growth and differentiation faetors the possible lysis of eells bearing the stimulatory antigens in assoeiation with MHC moleeules (Class I and Class II) the possible release of speeifie soluble factors (TsF) which may be direeted at either the TH eell or the B eell. 

The Arthus reaction. The phenomenon is a local one and occurs if a soluble antigen is introduced into the body when there is a great excess of antibody. The union between the two results in an acute inflammatory reachon which may involve complement, polymorphs, lymphokines or platelet aggregation, all of which enhance the inflammatoiy response. 

Wacker, W.B., Donoso, L.A., Kalsow, C.M. and Lipton, M.M. (1977). Experimental alleipc uveitis isolation, characterisation and localization of a soluble uveitopathogenic antigen from bovine retina. J. Immunol. 119, 1949-1948. 

Fig. 23 Saliva and serum IgA (primary and secondary) response following orally administered soluble antigen Streptococcus mutans cell wall extract (open circles, soluble antigen solid circles, liposome-encapsulated material) (phosphatidylcholine, phosphatidic acid, cholesterol). (From Ref. 277).

Ishii, H. Uchiyama, H., and Kazama, M., Soluble thrombomodulin antigen in conditioned medium is increased by damage of endothelial cells. Thromb. Haemost. 65,618-623 (1991). 

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