Dextran antibodies

Other systems which are currently studied as potential drug delivery systems are classified into two groups Firstly carriers which, by nature, form some kind of multi-or unilamellar vesicle, e.g. liposomes, erythrocyte ghosts, synthetic microcapsules, and secondly carriers based on naturally occurring macromolecules such as albumin, DNA, antibodies, Dextran (reviewed in Ref. >). 

There are also other immimological mechanisms, especially via IgG or IgM antibodies with immune complex formation, which can lead to similar clinical conditions [20, 34, 42] as has been shown in dextran anaphylaxis (table 1). Triggering of mast cells and basophils leads to release of various vasoactive mediators, among which histamine was the first recognized in 1908 (fig. 3,4) [6]. 

H, Devey ME Immunoglobulin class and subclass distribution of dextran-reactive antibodies in human reactors and non-reactors to clinical dex-tran. Allergy 1982 37 481-489. 

Some antigens, such as type 3 pneumococcal polysaccharide, EPS and other polymeric substances such as dextrans (poly-D-glucose) and levan (poly-D-fructose) can induce antibody synthesis without the assistance of TH cells. These are known as T-independent (Ti) antigens. Only one class of immunoglobulin (IgM) is synthesized and there is a weak memory response. 

Callahan LN, Phelan M, Mallinson M, Norcross MA. Dextran sulfate blocks antibody binding to the principal neutralizing domain of human immunodeficiency virus type 1 without interfering with gpl20-CD4 interactions. J Virol 1991 65 1543-1550. 

Attempts to study the entry of ES products into cells using markers of fluid phase endocytosis yielded unexpected results. When larvae browse resistant IEC-6 cells in the presence of extracellular fluorescent dextran, dextran enters the cytoplasm of a significant proportion of the cells in the mono-layer (Butcher et al., 2000). The parameters of dextran entry are most compatible with the conclusion that larvae wound the plasma membranes of IEC-6 cells that is, they create transient breaches in the membrane that allow impermeant markers to enter the cell (McNeil and Ito, 1989). Wounding is considered to be a common occurrence in intestinal epithelia (McNeil and Ito, 1989). Injured cells are able to heal their wounds by recruiting vesicles to seal the breach (Steinhardt et al., 1994). In an experimental system, healing allows the injured cell to retain cytoplasmic dextran. In epithelial cell cultures inoculated with T. spiralis larvae, the relationship between glycoprotein delivery and injury of plasma membranes is not clear, i.e. dextran-laden cells do not always stain with Tyv-specific antibodies and... 

Fitzgerald42 found that the antibody response of rabbits toward 1.5% aqueous dextran solutions (both types) varied with the nitrogen (t. e., bacterial) content of the dextran. Injections were administered both interperitoneally and intravenously, and no antibody production resulted when the nitrogen content of the dextrans was below 0.2%. 

Sugg and Hehre43 also obtained precipitin reactions with dextran or with sterile filtrates of sucrose broth cultures of L. mesenteroides (designated for convenience strain A) and not only anti-Leuconostoc sera, but also pneumococcus Types II, XII and XX antisera. Leuconostoc organisms cultured on D-glucose broth neither stimulated the production of dextran-reactive antibodies in rabbits, nor absorbed dextran-reactive antibodies from sera, as did organisms cultured on sucrose. Absorption with the homologous bacteria (Leuconostoc, pneumococcus Types II,... 

Dextran resulting from the action of another strain of L. mesenteroides (designated for convenience, strain B) was more soluble than strain A dextran and exhibited somewhat different immunological reactions. This strain B dextran reacted only slightly with pneumococcus Type XII antisera and had a narrower zone of antigenic reactivity than the strain A dextran. In addition, the strain A organisms exhibited a greater capacity to absorb antibodies reactive with the B dextran than did the B bacteria to absorb antibodies reactive with the A dextran. 

The most successful technique has appeared to be the binding of antibodies to a matrix of carboxymethyl dextran macromolecules attached to... 

Figure 5. The binding of antibodies to carboxymethyl dextran matrix attached to a sensor surface.

A second method of immunotoxin preparation by reductive amination involves the use a polysaccharide spacer. Soluble dextran may be oxidized with periodate to form a multifunctional crosslinking polymer. Reaction with antibodies and cytotoxic molecules in the presence of a reducing agent forms multivalent immunotoxin conjugates. The following sections discuss these options. 

Figure 21.15 A periodate-oxidized dextran polymer may be reacted with both an antibody and an intact toxin component using reductive amination to form a multivalent immunotoxin complex.

Add 10 mg of the protein to be coupled to the dextran solution. Other ratios of dextran-to-protein may be used as appropriate. For instance, if more than one protein or a protein plus a smaller molecule are both to be conjugated to the dextran backbone, the amount of protein added initially may have to be scaled back to allow the second molecule to be coupled latter. Many times, a small molecule such as a drug will be coupled to the dextran polymer first, and then a targeting protein such as an antibody conjugated secondarily. The optimal ratio of components forming the dextran conjugate should be determined experimentally to obtain the best combination possible. 

In a somewhat similar scheme, Noguchi et al. (1992) prepared a carboxylate spacer arm by reacting 6-bromohexanoic acid with a dextran polymer. The carboxylate then was aminated with ethylene diamine to form an amine-terminal spacer (Figure 25.15). This dextran derivative finally was reacted with N-Succinimidyl 3-(2-pyridyldithio)propionate (SPDP) (Chapter 5, Section 1.1) to create the desired sulfhydryl-reactive polymer (Section 2.4, this chapter). The SPDP-activated polymer then could be used to prepare an immunoconjugate composed of an antibody against human colon cancer conjugated with the drug mitomycin-C. 

Brunswick, M., Finkelman, F.D., Higher P.F., Inman, J.K., Dintzis, H.M., and Mond, J.J. (1988) Picogram quantities of anti-Ig antibodies coupled to dextran induce B cell proliferation. /. Immunol. 140, 3364-3372. 

Manabe, Y., Tsubota, T., Haruta, Y., Okazaki, M., Haisa, S., Nakamura, K., and Kimura, I. (1983) Production of monoclonal antibody-bleomycin conjugate utilizing dextran T40 and the antigen-targeting cytotoxicity of the conjugate. Biochem. Biophys. Res. Comm. 115, 1009. 

Noguchi, A., Takahashi, T., Yamaguchi, T., Kitamura, K., Takakura, Y., Hashida, M., and Sezaki, H. (1992) Preparation and properties of the immunoconjugate composed of anti-human colon cancer monoclonal antibody and mitomycin C—Dextran conjugate. Bioconjugate Chem. 3, 132-137. 

Five immobilization matrices have been tested and compared. These include a dextran layer on the sensor surface, succinic anhydride modified surface, monomer glutaraldehyde activated surface, polyglutaraldehyde activated surface and strepta-vidine/biotinylated antibody coated surface. 

---