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PubMed1952

Immunochemical studies of antitoxin produced in normal and allergic individuals hyperimmunized with diphtheria toxoid. II. A comparison between the immunological properties of precipitating and non-precipitating (skin-sensitizing) antitoxins.

1. The immunological properties of two contrasting types of human antisera, each containing a high titer of diphtheria antitoxin, have been investigated. 2. Sera which contain only non-precipitating antitoxin exhibit most of the properties of atopic reagin-containing sera. This type of antitoxin is capable of sensitizing normal human skin to toxin or toxoid and remains for many weeks in the injected area. It exhibits no Danysz effect, does not fix complement unless very large amounts of serum are used, and can be specifically coprecipitated by addition of precipitating antitoxin and toxin. On the other hand, it is capable of sensitizing guinea pigs to fatal anaphylactic shock. Heating at 56 degrees C. for 4 hours destroys the skin-sensitizing properties and results in almost quantitative conversion to a modified antitoxin which is capable of blocking the wheal and erythema reaction caused by injection of toxoid into sensitized skin. Heating at 56 degrees C. does not result in an appreciable loss of neutralizing power as judged by tests in rabbit and human skin. The anaphylactogenic property of nonprecipitating antibody is likewise unaffected by heat at 56 degrees C. 3. Precipitating antitoxin is incapable of sensitizing normal skin to toxin or toxoid and disappears rapidly from the injected sites. It fixes complement to high titer and sensitizes guinea pigs to fatal anaphylactic shock. It was possible to demonstrate inhibition of the wheal and erythema reaction in sensitized skin by injecting certain mixtures of precipitating antitoxin and toxoid. 4. The two antitoxic sera studied in greatest detail represented extreme cases. Many persons immunized with toxoid developed both precipitating and nonprecipitating antitoxin simultaneously.

Animals↗
PubMed1981

Effect of formalin toxoiding on Pseudomonas aeruginosa toxin A: biological, chemical, and immunochemical studies.

We investigated the effect of Formalin toxoiding on the biological, chemical, and immunological activities of Pseudomonas aeruginosa toxin A. Formalin treatment alone resulted in a 1,000-fold decrease in toxin-induced cell cytotoxicity and altered the antigenicity of the toxin A molecule without adversely affecting enzymatic activity. Competitive blocking experiments indicated that Formalin-mediated detoxification proceeded via alterations in a region of the toxin molecule other than the active site of the enzyme. The addition of lysine to Formalin-toxin mixtures not only increased the rate and extent of detoxification and antigenic alteration, but also completely destroyed enzymatic activity. The immunogenicities of different toxoids varied substantially. Upon dialysis and storage, Formalin-derived toxoids underwent partial toxic reversion, whereas a Formalin-lysine-derived toxoid did not. The sodium dodecyl sulfate-polyacrylamide gel patterns of Formalin- and Formalin-lysine-treated toxins indicated that these treatments caused the formation of a heterogenous group of high-molecular-weight species and produced substantial changes in the electrophoretic mobility of toxin A.

ADP Ribose Transferases↗
PubMed1988

Synthetic peptides of Shiga toxin B subunit induce antibodies which neutralize its biological activity.

Shiga toxin B chain, the binding subunit of Shiga toxin, was recently purified; and the amino acid sequence of this 7,716-dalton polypeptide was determined (N.G. Seidah, A. Donohue-Rolfe, C. Lazure, F. Auclair, G. T. Keusch, and M. Chretien, J. Biol. Chem. 261:13928-13931, 1986). In the present study, synthetic peptides corresponding to three overlapping sequences from the N-terminal region of this subunit were prepared. The peptides synthesized consisted of residues 5 to 18, 13 to 26, and 7 to 26. This region coincides with the major peak of hydrophilicity and surface area residues predicted from a computer analysis. For the purpose of immunization, the peptides either were conjugated with a protein or synthetic carrier or were polymerized with glutaraldehyde. Antisera against these peptide derivatives raised in rabbits reacted not only with the respective homologous peptide but also to a comparable extent with the intact Shiga toxin. The anti-peptide antisera effectively neutralized the various biological activities of the Shiga toxin, namely, cytotoxicity to HeLa cells, enterotoxic activity (the fluid secretion into ligated ileal loops in rats), and neurotoxicity in mice. Furthermore, active immunization with the peptide conjugates was found to protect mice against the lethal effect of Shiga toxin.

Amino Acid Sequence↗
PubMed1984

Clostridium difficile isolation in neonates in a special care unit. Lack of correlation with necrotizing enterocolitis.

The stools of 78% of 45 infants in a Special Care Baby Unit yielded Clostridium difficile on culture, and in 67% of these it was possible to detect C. difficile toxin by means of a tissue culture technique. The stools of six of the seven infants with necrotizing enterocolitis were positive for C. difficile, but neither of the two most severely affected contained C. difficile toxin. The incidence of C. difficile isolation was similar in infants treated by exchange transfusion, those treated with antibiotics, those of low birth weight, and those with respiratory distress. The serum of only 2 of 28 infants and 1 of 20 mothers contained a neutralizing factor to C. difficile toxin. The present study does not support a role for C. difficile in neonatal disorders and in particular necrotizing enterocolitis. The reason for the apparent tolerance of the neonatal bowel to C. difficile toxin remains to be explained.

Antitoxins↗
PubMed1961

Effects of bacterial endotoxin on rabbit platelets. I. Platelet aggregation and release of platelet factors in vitro.

Incubation of platelet-rich rabbit plasma with E. coli endotoxin at 37 degrees C results in platelet aggregation and transfer of platelet 5-hydroxytryptamine to plasma. Release of 5HT is influenced by dose of endotoxin, type of anticoagulant, and temperature of incubation. A heat-labile plasma factor is necessary for the platelet-endotoxin interaction. Additional studies have shown that incubation of endotoxin with platelet-rich rabbit plasma also results in release of platelet phospholipid and bactericidins active against B. subtilis.

Animals↗