Hapten determinants

Position of handle on target molecule Distal to hapten determinant groups Avoid attachment to functional groups... 

Grabbe, S. et al., Dissection of antigenic and irrative effects of epicutaneously applied haptens in mice. Evidence that not the antigenic component but non-specific proinflam-matory effects of haptens determine the concentration-dependent elicitation of allergic contact dermatitis, 7. Clin. Invest., 98, 1158, 1996. 

The fewer the active functions are available to serve as haptenic determination, the lesser will be the specificity of the reaction in radioimmunoassay in other words, the greater the number of antigenic determinants in a hapten molecule the more specific shall be its reaction with its antibody. 

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. 

As described in Part I, increases in affinity or avidity for antigen are characteristic features of the immune response. In antibody responses to well-defined haptenic determinants, the affinity of the antibodies for the hapten had been shown to increase during the period after immunization this was interpreted in terms of clonal selection, cells with antibody-receptors of higher affinity successfully competing for antigen against cells with receptors of lower affinity. 

In a different approach, Azuma et al. (1984) recombined the same heavy chain with two different light chains. The reconstituted immunoglobulins, which were identical except for a single Phe/Tyr replacement at the VXJX junction, differed in affinity for a haptenic determinant by a factor of about 100. This sequence difference is probably a result of variation in the position of VJ recombination and not of somatic mutation. Chain recombination was also used by Berek and Milstein (1987) to show that a single residue in CDR1 of a VK region can have a substantial effect on affinity. 

FIGURE 16.10 Hapten determinants formed by penicillins that contain a p-lactam ring linked to various side chains (R). The primary route of haptenation involves acylation of the E-amino group of lysine residues of serum or cell surface proteins to form a penicilloyl or major antigenic determinant. Isomerization of penicillin leads to the generation of compounds that form disulfide bonds wdth the cysteine sulfhydryl groups of proteins. These epitopes are termed minor determinants. 

S. J. Gross and J. R. Soares, Hapten determinants and purity—the key to immunologic specificity, Imtmttwassays for Drugs Subject to Abuse (S, J. MuI6,1, Sunshine, M. Braude, and R. E. Willette, eds.), CRC Press, Cleveland, Ohio, 1974, pp. 3-11. 

A large body of data has been amassed indicating that the structure of antibodies elicited by a T cell dependent form of an antigenic determinant varies substantially in comparison to a T cell independent form of the same determinant. The variation in predominant isotypic class of antibody elicited by T dependent as well as independent antigens is well documented (reviewed in [146]). Expression of idiotypic determinants by the elicited antibody population has been observed to differ substantially in responses to T cell dependent and independent forms of the same haptenic determinant [147]. The participation of T cells during a humoral immune response clearly influences the structure of the antibodies elicited. 

B-cell determinants or haptenic determinants, as they are frequently called, are comparatively well defined with regard to dimensions and specificity relationships. The problem of their size has attracted considerable interest during the last two decades and seems now satisfactorily elucidated. A recent careful review of these aspects has been provided by Goodman (1975). It has been known for some time that haptenic groups such as DNP and BPO do not comprise the entire deter-... 

Assem ESK, Vickers MR (1974) Tests for penicillin allergy in man. II. The immunological cross-reaction between penicillins and cephalosporins. Immunology 27 255 Assem ESK, Vickers MR (1975) Investigation of the response to some haptenic determinants in penicillin allergy by skin and in vitro allergy tests. Clin Allergy 5 43... 

Skin tests with various tetracycline compounds in different concentrations have been performed by many clinicians. Unfortunately, non-sensitizing conjugates of tetracyclines with small polypeptide carriers are not available. This is mainly due to our inadequate knowledge of the haptenic determinants responsible for tetracycline allergies. Therefore no effective diagnostic skin tests exist at present. 

Affinity reagents consist of reactive moieties which either can be attached to or are an integral part of a haptenic determinant. The effectiveness of such probes depends on maintaining a much higher concen-... 

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