The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin.

Covalent linkage of the A chain of ricin to the LICR-LOND-Fib75 monoclonal antibody produced an immunotoxin, Fib75-SS-ricin A, which demonstrated immunospecific toxicity to human bladder carcinoma cells in tissue culture (Forrester et al., 1984). The present studies have shown that ricin B chain pot...

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Main Authors:	Timar, J., McIntosh, D. P., Henry, R., Cumber, A. J., Parnell, G. D., Davies, A. J.
Format:	Online
Language:	English
Published:	1991
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1977687/

id	pubmed-1977687
recordtype	oai_dc
spelling	pubmed-19776872009-09-10 The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin. Timar, J. McIntosh, D. P. Henry, R. Cumber, A. J. Parnell, G. D. Davies, A. J. Research Article Covalent linkage of the A chain of ricin to the LICR-LOND-Fib75 monoclonal antibody produced an immunotoxin, Fib75-SS-ricin A, which demonstrated immunospecific toxicity to human bladder carcinoma cells in tissue culture (Forrester et al., 1984). The present studies have shown that ricin B chain potentiates the toxicity of the immunotoxin by two orders of magnitude and also significantly increases the rate of protein synthesis inhibition. Using immunoelectron microscopy, the receptor-mediated endocytosis and intracellular routing of the immunotoxin was studied with and without ricin B chain treatment after immunolocalisation of the conjugate. Fib75-SS-ricin A was internalised by the EJ cells predominantly in uncoated pits and vesicles and directed to the endosomes. Some degradation of the complex appeared to take place in multivesicular endosomes at early timepoints and 24 h after internalisation, most of the immunotoxin was found in lysosomes. Some ricin A chain epitopes were detected in Golgi vesicles. Cells treated with immunotoxin and ricin B chain endocytosed the complex predominantly in coated pits and coated vesicles. Using pre-embedding immunoperoxidase techniques, ricin chains were found in the whole Golgi complex and most of the conjugate escaped lysosomal degradation. Internalised immunotoxin was recycled back to the plasma membrane in an active form associated with vesicles which appeared to be derived predominantly from multivesicular endosomes. A similar mode of recycling has recently been reported (McIntosh et al., 1990) for ricin holotoxin in the same cell line. These observations may explain the potentiating effect of toxin B chains in the antibody-directed targeting of toxin A chains. 1991-10 /pmc/articles/PMC1977687/ /pubmed/1911213 Text en
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Timar, J. McIntosh, D. P. Henry, R. Cumber, A. J. Parnell, G. D. Davies, A. J.
spellingShingle	Timar, J. McIntosh, D. P. Henry, R. Cumber, A. J. Parnell, G. D. Davies, A. J. The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin.
author_facet	Timar, J. McIntosh, D. P. Henry, R. Cumber, A. J. Parnell, G. D. Davies, A. J.
author_sort	Timar, J.
title	The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin.
title_short	The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin.
title_full	The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin.
title_fullStr	The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin.
title_full_unstemmed	The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin.
title_sort	effect of ricin b chain on the intracellular trafficking of an a chain immunotoxin.
description	Covalent linkage of the A chain of ricin to the LICR-LOND-Fib75 monoclonal antibody produced an immunotoxin, Fib75-SS-ricin A, which demonstrated immunospecific toxicity to human bladder carcinoma cells in tissue culture (Forrester et al., 1984). The present studies have shown that ricin B chain potentiates the toxicity of the immunotoxin by two orders of magnitude and also significantly increases the rate of protein synthesis inhibition. Using immunoelectron microscopy, the receptor-mediated endocytosis and intracellular routing of the immunotoxin was studied with and without ricin B chain treatment after immunolocalisation of the conjugate. Fib75-SS-ricin A was internalised by the EJ cells predominantly in uncoated pits and vesicles and directed to the endosomes. Some degradation of the complex appeared to take place in multivesicular endosomes at early timepoints and 24 h after internalisation, most of the immunotoxin was found in lysosomes. Some ricin A chain epitopes were detected in Golgi vesicles. Cells treated with immunotoxin and ricin B chain endocytosed the complex predominantly in coated pits and coated vesicles. Using pre-embedding immunoperoxidase techniques, ricin chains were found in the whole Golgi complex and most of the conjugate escaped lysosomal degradation. Internalised immunotoxin was recycled back to the plasma membrane in an active form associated with vesicles which appeared to be derived predominantly from multivesicular endosomes. A similar mode of recycling has recently been reported (McIntosh et al., 1990) for ricin holotoxin in the same cell line. These observations may explain the potentiating effect of toxin B chains in the antibody-directed targeting of toxin A chains.
publishDate	1991
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1977687/
_version_	1611401081222332416

The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin.

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