Immunotoxin conjugates preparation

Injection of immunotoxin conjugates prepared from mouse monoclonals usually... 

SMPT or sulfo-LC-SMPT has been used to develop conjugates for in vivo delivery of siRNA to hepatocytes (Rozema et al., 2007), in preparing an anti-CD25-immunotoxin conjugate (Mielke et al., 2007), and in preparing conjugates for selective depletion of donor lymphocytes in stem cell transplantation (Solomon et al., 2005). 

PDPH has been used in the preparation of immunotoxin conjugates (Zara et al., 1991). It has also been used to create a unique conjugate of nerve growth factor (NGF) with an... 

Since immunotoxin conjugates are destined to be used in vivo, their preparation involves more critical consideration of crosslinking methods than most of the other conjugation protocols described in this book. The following sections discuss the problems associated with toxin conjugates and the main crosslinking methods for preparing them. 

Regardless of their method of preparation, the required and ideal characteristics of immunotoxin conjugates can be summarized in the following points ... 

Preparation of Immunotoxin Conjugates via Disulfide Exchange Reactions... 

This multi-step crosslinking method employing SPDP on both molecules has been used to prepare a number of immunotoxin conjugates (Edwards et al., 1982 Thorpe et al., 1982 Colombatti et al., 1983 Wiels et al., 1984 Vogel, 1987 Reiter and Fishelson, 1989). While... 

SMPT often is used in place of SPDP for the preparation of immunotoxin conjugates. The hindered disulfide of SMPT has distinct advantages in this regard. Thorpe et al. (1987) showed that SMPT conjugates had approximately twice the half-life in vivo as SPDP conjugates. Antibody-toxin conjugates prepared with SMPT possess a half-life in vivo of up to 22 hours, presumably due to the decreased susceptibility of the hindered disulfide toward reductive cleavage. 

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. 

PDPH has been used in the preparation of immunotoxin conjugates (Zara et al., 1991). It has also been used to create a unique conjugate of NGF with an antibody directed against the transferrin receptor OX-26, which could traverse the blood-brain barrier (Friden et al., 1993). Labeling of antibody molecules with PDPH at oxidized polysaccharide sites followed by reduction to free the sulfhydryl has been used to form a technetium-99m complex for radiopharmaceutical use (Ranadive et al., 1993) (Chapter 8, Section 2.5). 

---