Antigen combinations

In vivo reproducible results can only be achieved if the liposome-drug or -antigen combinations are thoroughly characterized upon preparation in terms of their physical and chemical properties and, besides, if the stability during storage is ensured. In this chapter both the pharmaceutical (preparation, characterization, and stability) aspects and the therapeutic potentials and limitations of drug and antigen delivery with liposomes will be discussed. 

Evolution has provided a masterful solution to this problem. When a microbe enters the body, its component antigens combine with only those lymphocytes whose surface receptor is complementary to the shape of those antigens. The cells that bind antigen become activated and proliferate clonally to form a large... 

If a free amino group forms a portion of the protein that is essential for activity (e.g., the antigen-combining site for antibody), biotinylation with the succinimide ester will lower or destroy the activity of the protein, and other methods of labeling should be tried. Biotin hydrazide has been used to modify the carbohydrate moieties of antibodies (10,11). Other alternatives are the thiol-reactive biotin maleimide (12) or biotin iodoacetamide (13). 

Nonspecific background problems are the result of primary or secondary antibody binding to the tissue through interactions that do not involve the antigen combin-... 

G4. Gleioh, G. J., Bieger, R. C., and Stankievic, R., Antigen combining activity associated with immunoglobulin D. Science 165, 606 (1969). 

In this case, immobilization is made in such a way that the antigen-combining sites of the antibody are not involved, thereby increasing the fraction of fully... 

IgE antigens combined with in vitro tests of cross-reactions of IgE and sequenced antigens, as it has been found that the basic condition for positive cross-reactivity is the high structural compatibility (homology) of reagents. Compared to B-cells, T-cell cross-reactivity is far more difficult to assess because the mechanism of T-cell effects is more diverse and involves both the phase of immunological response and the effect phase of the allergic reaction. 

Antibodies from both natural or adaptive immunity are characterized by an extraordinary diversity of structure, considering there are more than 1 x 107 and perhaps as many as 109 structurally different antibody there are molecules present in every individual, each with unique amino acid sequences in their antigen-combining sites [57, 58]. 

Different methods are used to immobilize covalently the proteins to HPLC supports. The coupling procedures imply various activation chemistries via epoxide-, diol-, or aldehyde-silica [51,52], Generally, the immobilized antibodies are randomly oriented. Dihydrazide-silica supports are used for an oriented immobilization of the antibody through its carbohydrate residues [53]. Another approach is to bind the antibody to protein A or protein G surfaces [17]. The antibody will bind through the Fc portion, leaving the antigen combining sites oriented away from the support. 

---