A chain conjugation

A-chain immunotoxins, however, may not be quite as cytotoxic as conjugates formed from intact toxin molecules (Manske et al., 1989). In an alternative approach to A chain use, the intact toxin of two-subunit proteins is directly conjugated to a monoclonal without isolation of the A chain. Conjugation of an antibody with intact A-B chain toxins can be done without a cleavable linker, as long as the A chain can still separate from the B chain once it is internalized. Therefore, it is important to avoid intramolecular crosslinking during the conjugation process which can prevent release of the A-B complex. In addition, since the B chain... 

Hashimoto, N., Takatsu, K., Masuho, Y., Kishida, K., Hara, T., and Hamaoka, T. (1984) Selective elimination of a B cell subset having acceptor site(s) for T cell-replacing factor (TRF) with biotinylated antibody to the acceptor site(s) and avidin-ricin A chain conjugate./. Immunol. 132, 129-135. 

Masuho, Y., Kishida, K., Saito, M., Umemoto, N., and Hara, T. (1982) Importance of the antigen-binding valency and the nature of the cross-linking bond in ricin A-chain conjugates with antibody. J. Biochem. (Tokyo) 91, 1583. 

Raso, V., and Basala, M. (1984) A highly cytotoxic human transferrin - Ricin A chain conjugate used to select receptor-modified cells./. Biol. Chem. 259, 1143. 

The preparation of cytotoxic antibody-A chain conjugates using chemical crosslinking methods has two main requirements. First, the number of crosslinkers introduced per antibody molecule should be low. This minimizes the risk that the antigen-binding capability of the antibody will be compro-... 

Fig. 2. SDS-PAGE of an antibody-toxin conjugate preparation. (A) Antibody (starting material). (B) Abrin A chain conjugate (pooled fractions shown in Fig. 1). Samples were prepared under nonreducing conditions and run on a 2—27% gradient polyacrylamide gel.

Raso V, Ritz J, Basala M, et al. Monoclonal antibody-ricin A chain conjugate selectively cytotoxic for cells bearing the common acute lymphoblastic leukemia antigen. Cancer Res 1982 42 457-464. 

Pincus, S. H., Wehrly, K., and Chesebro, B. (1989) Treatment of HIV tissue culture infection with monoclonal antibody-ricin A chain conjugates. J. Immunol. 142, 3070-3075. 

Raso, V, and Basala, M. (1985) Study of the transferrin receptor using a cytotoxic human transferrin—ricin A chain conjugate, in Receptor-Mediated Targeting of Drugs (G. Gre-goriadis, ed.), Vol. 2, p. 73. Plenum, New York. 

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