Selection reactive immunization

Antibody Catalysis. Recent advances in biocatalysis have led to the generation of catalytic antibodies exhibiting aldolase activity by Lemer and Barbas. The antibody-catalyzed aldol addition reactions display remarkable enantioselectivity and substrate scope [18]. The requisite antibodies were produced through the process of reactive immunization wherein antibodies were raised against a [Tdiketone hapten. During the selection process, the presence of a suitably oriented lysine leads to the condensation of the -amine with the hapten. The formation of enaminone at the active site results in a molecular imprint that leads to the production of antibodies that function as aldol catalysts via a lysine-dependent class I aldolase mechanism (Eq. 8B2.12). 

Reactive immunization is a fundamentally different approach to selecting antibody pockets that contain functional groups. This method employs mechanism-based inhibitors as haptens these molecules react covalently with appropriately functionalized antibodies, allowing direct selection of active clones from large pools of inactive variants. When a suitable substrate is used in place of the inhibitor, reactive residues in the selected antibodies can often mediate its conversion into product. 

Aldolase antibodies obtained by reactive immunization are notable for high activity, broad substrate specificity, and high selectivities [53]. Rate accelerations are typically in the range 105 to 107-fold over background. Although the k /K values are 102 to 104 lower than those of aldolase enzymes, these are among the most efficient antibody catalysts described to date. Their efficacy is all the more notable in light of the inherently complex, multistep process they catalyze. 

In an effort to induce catalytic residues during immunization, Lerner et al. reported that efficient catalytic antibodies can be generated by a process called reactive immunization . In this method a chemically reactive hapten is used to create a covalent bond with a catalytic residue in the antibody binding pocket, thereby allowing its selection and amplification in the course of immunization. Aldolase antibodies were obtained using a reactive 1,3-diketone, which formed a covalent bond with a lysine residue in the antibody binding pocket (see Sect. 2.8). A similar experiment yielded esterase antibodies by immunization... 

Traditionally, the desired monoclonal antibody is selected on the basis of binding affinity to the TSA. This approach led to a multitude of effective catalytic antibodies, the rate acceleration of which, however, is usually orders of magnitude below that of comparable enzymes. Furthermore, detailed mechanistic investigations often revealed a different catalysis mechanism than originally assumed. A different approach for the selection of catalytic antibodies is the reactive immunization where the selection criterion from simple binding is changed to chemical reactivity. 

Lymphoid dendritic cells promote negative selection in the thymus. This may be attributed to their ability to induce fas-mediated apoptosis. Based on their ability to cause apoptosis and their ability to eliminate self-reactive T cells, lymphoid dendritic cells exhibit a regulatory function instead of a stimulatory immune effector function. Myeloid dendritic cells also have differential effects. For example, T cells can be primed to selectively activate THi responses by CD14-derived myeloid dendritic cells. Naive B cells can be activated in the presence of CD40L and IL-2 to secrete IgM by CD34+, CD14-derived myeloid dendritic cells. This effect on naive B cells is not observed with CD la-derived dendritic cells. 

Potentized homeopathic medicines have preferential action on sides of the body some are more effective on one side than on the other. This differential effect of the medicines with respect to laterality can be traced to functional asymmetry of the human brain. The brain can asymmetrically modulate nurochemical, neuroendocrine and immune reactivity. Potentized drugs are very often selected on the basis of time modalities of symptoms of a disease. The time modalities of the drug action can be correlated with the internal clock or biological rhythms of organisms which are disturbed in diseased conditions. Melatonin, secreted in the brain, has marked influence on the circadian rhythms. 

Recent studies show that nucleosome/antinucleosome immune complexes contribute more to lupus nephritis. Serum anti-dsDNA reactivity is always associated with antinucleosome reactivity (A18, B26, B28, B29, C9). Even the highly purified monoclonal and polyclonal anti-dsDNA antibodies selected by affinity chromatography bind to isolated dsDNA and also to nucleosomes (C9, L23). Hybridoma-secreting anti-DNA can also form immune complexes in vitro with nucleosomes released from dying hybridomas in culture (F9). Finally, the binding of an anti-DNA antibody to a nucleosome may render the immune complex more positive and thereby make it more prone to bind to the GBM (T2). 

In contrast to human antibodies derived from large naive or synthetic human antibody libraries, antibodies from immune animals were subjected to in vivo selection and are therefore more likely to recognize a given antigen selectively (i.e., without cross-reactivity to another antigen). 

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