Antibodies dextran conjugate with

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. 

Due to its hydrophilic nature, dextrans have also been used to conjugate bioactive substances (e.g., dmgs, enzymes, hormones, and antibodies) to prolong circulation lifetimes, increase stability in vivo, or depress antigenicity. For example, dextran nanoparticles have been conjugated with insulin for oral delivery. These nanocarriers can protect insulin from degradation in the gut and modulate release profiles. ... 

Dextran was oxidized with sodium periodate to the corresponding polyaldehyde and daunomycin was coupled with a part of the aldehydes via its amino sugar. This complex was further bound to the lysines of the antibody. This conjugate can either be used directly or stabilized by further reduction with sodium borohydride. 

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. 

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