Word Finder - antitoxin

definition

An antibody that is capable of neutralising specific toxins that are causative agents of disease.

It may be stated that while in certain instances the union of toxin and antitoxin may be reversible, all the facts established cannot be explained on this simple hypothesis of reversible action.

Diphtheria antitoxin is usually given intravenously.

The next step was to endeavour so to modify and weaken the virus as to enable it to be used as a preventive or as an antitoxin.

In recent years the relations of toxin and antitoxin, still obscure, have been the subject of much study and controversy.

In view of the fact that antitoxin has a direct action on toxin, we may say that theoretically this may take place in one of two ways.

Still another view, advocated by Bordet, is that the union of toxin and antitoxin is rather of physical than of strictly chemical nature, and represents an interaction of colloidal substances, a sort of molecular deposition by which the smaller toxin molecule becomes entangled in the larger molecule of antitoxin.

The first of these, which would imply a process of a very remarkable nature, is disproved by what is observed after bleeding an animal whose blood contains antitoxin.

In such a case it has been shown that, without the introduction of fresh toxin, new antitoxin appears, and therefore must be produced by the living tissues.

Further, these molecules in the nervous system present the same susceptibility to heat and other physical agencies as does tetanus antitoxin.

In specific germ diseases a similar antitoxin forms, and in cases which recover it counteracts the toxin, while the germs are destroyed by the tissues.

In 1891, Emil von Behring produced an antitoxin from the blood of animals for curing diphtheria.

The disease can be prevented by immunization with tetanus toxoid or the use of antitoxin which is routinely carried out in horses.

Lastly it may be mentioned that when a toxin has some action which can be demonstrated in a test-tube experiment, for example, a dissolving action on red corpuscles, this action may be annulled by previously adding the antitoxin to toxin; in such a case the intervention of the living tissues is excluded.

It is strongly supported by Ehrlich, who, in his so-called " side-chain " (Seitenkette) theory, explains antitoxin production as an instance of regeneration after loss.

Older children and adults can be treated with injections of a specific antitoxin for botulism if it can be administered within 72 hours after symptoms are first observed.

Infants, however, cannot receive this antitoxin and are usually treated instead with injections of human botulism immune globulin (BIG), an antiserum that neutralizes the botulinum toxin.

Older children and adults with botulism are sometimes treated with an antitoxin derived from horse serum that is distributed by the Centers for Disease Control and Prevention.

The antitoxin (effective against toxin types A, B, and E) inactivates only the botulinum toxin that is unattached to nerve endings.

Early injection of the antitoxin, ideally within 24 hours of onset of symptoms, can preserve nerve endings, prevent progression of the disease, and reduce mortality.

Unfortunately, infants cannot receive the antitoxin used for adults.

This antitoxin can provide protection against A and B toxins for approximately four months.

Aside from the specific antitoxin, no therapeutic drugs are used to treat botulism.

The risk of serious complications is increased as the time between onset of symptoms and the administration of antitoxin increases, and as the size of the membrane formed increases.

The most important step is prompt administration of diphtheria antitoxin, without waiting for laboratory results.

The antitoxin is made from horse serum and works by neutralizing any circulating exotoxin.

People who are sensitive (about 10%) must be desensitized with diluted antitoxin, since as of 2004 the antitoxin is the only specific substance that counteracts diphtheria exotoxin.

No human antitoxin is available for the treatment of diphtheria.

They are not a substitute for treatment with antitoxin.

In addition, persons should be immunized against diphtheria after recovery, because having the disease does not always induce antitoxin formation and protect them from reinfection.

The prognosis depends on the size and location of the membrane and on early treatment with antitoxin; the longer the delay, the higher the death rate.

Toxins may thus become so closely keyed into their corresponding atom groups, as for instance in tetanus, that they are no longer free to combine with the antitoxin; or, again, an antitoxin injected before a toxin may anticipate it and, preventing its mischievous adhesion, dismiss it for excretion.

The facts with regard to passive immunity were thus established and were put to practical application by the introduction of diphtheria antitoxin as a therapeutic agent in 1894.

In the earlier experiments on smaller animals the potency of the toxin was modified for the first injections, but in preparing antitoxin for therapeutical purposes the toxin is used in its unaltered condition, the horse being the animal usually employed.

His view as to the dual composition of the toxin molecule has already been mentioned, and it is evident that if the haptophorous or combining group has its affinity satisfied by union with antitoxin, the toxin will no longer combine with living cells, and will thus be rendered harmless.

There is, however,, still dispute with regard to the exact nature of the union of toxin and antitoxin.

He found, however, that if he took the largest amount of toxin which was just neutralized by a given amount of antitoxin, much more than a single dose of toxin had to be added before a single dose was left free.

Accordingly, the most actively toxic molecules will be neutralized first, and those which are left over, that is, uncombined with antitoxin, will have a weaker toxic action.

Arrhenius, who hold that the union of toxin and antitoxin is comparatively loose, and belongs to the classof reversible actions, being comparable in fact with the union of a weak acid and base.

If such were the condition there would always be a certain amount both of free toxin and of free antitoxin in the mixture, and in this case also considerably more than a dose of toxin would have to be added to a " neutral mixture " before the amount of free toxin was increased by a dose, that is, before the mixture became lethal.

Its serum in course of time is found to contain something (antitoxin) which has the power of neutralizing the toxin secreted by the organism when parasitical upon the body.

The unit of antitoxin in Ehrlich's new standard is the amount requisite to antagonize i oo times the minimum lethal dose of a particular toxin to a guinea-pig of 250 grm.

Kanthack and Cobbett, that in certain instances the toxin can be made to pass through a gelatine membrane, whereas the antitoxin cannot, its molecules being of larger size.

One other important fact in support of what has been stated is that a toxin may have its toxic action diminished, and may still require the same amount of antitoxin as previously for neutralization.

The origin of antitoxin is of course merely a part of the general question regarding the production of anti-substances in general, as these all combine in the same way with their homo logous substances and have the same character of g toxin.

In antitoxin production this combination takes place, though not in sufficient amount to produce serious toxic symptoms. It is further supposed that the combination being of somewhat firm character, the side-chains thus combined are lost for the purposes of the cell and are therefore thrown off.

It has, moreover, been found that the serum of various animals has a certain amount of antitoxic action, and thus the basis for antitoxin production, according to Ehrlich's theory, is afforded.

It has been found, for example, that a toxin may pass through such a filter while an antitoxin may not.

The laws of antitoxin production and action are not confined to bacterial toxins, but apply also to other vegetable and animal toxins, resembling them in constitution, viz.

The production of antitoxin is one of the most striking facts of biological science, and two important questions with regard to it must next be considered, viz.

As, however, most of the work has been done with regard to antitoxin production we may consider here the theoretical aspect of the subject.