HEALTH NOTES.

Otago Witness, Issue 3801, 18 January 1927, Page 25

HEALTH NOTES.

IMMUNITY.

PREPARING VACCINES.

Contributed by the Department of Health. ■„

As- already stated in the article on Immunity, pub : ished last week, biologic therapy- may be defined as tne medical treatment of diseases with products made by the agency of the microbes concerned. It includes all forms of treatment with vaccines, inoculations, toxins, and antitoxins, and the preparation of the same It is one of the newest branches of medicine, and so technical that it remains largely in the hands of specialists. The lessons learnt in the study of natural immunity are used to set in motion artificially those physiologic processes by which the body protects itself against microbes. Laboratory toxins or vaccines for use m biologic-therapy are prepared as follows:.— Cultures of microbes are grown on suitable media, their toxins collected, freed from all living microbes, sterilised, completely, and the quantity and strength measured and standardised, so that the toxins can be measured out into doses, just as drug tinctures can be measured out into doses. Jt is necessary to have it clearly understood that toxins and anti-toxins, as prepared in laboratories, are dead sterile drug?, in dead sterile fluids. .They are no more alive than a tincture of digitalis is alive. Digitalis is. made-from a foxglove that grew in the' earth, its poison or “active principle” is extracted, standardised, and dissoloved in spirit. Biologic toxins are-made from microbes (and most microbes belong to the vegetable kingdom) Tne microbes grow in animals and certain artificial media such as agar or broth, their toxins are extracted, standardised, and dissolved in a-solution which suits them. But thev are no more the microbes themselves than digitalis is a foxglove, or cochineal is a bettie. ' \ „„„„ FOR USE AS DRUGS.

Laboratory anti-toxins for use as drugs in the treatment of acute diseases are prepared as follows: —Individuals, either men or animals, who have made a successful recovery from an acute disease, in doing so have produced antitoxins in their blood. If their blood is drawn off, the clot, etc., separated, the clear serum that remains contains anti-toxins. The serum can be sterilised so that it is no more n live thing than a solution of digitalis is -alive. For certain common diseases (such as diphtheria), the blood of immunised horses is used. The technique for some of them (such a 8 diphtheria) is now so perfect that the potency and amount can be accurately measured. But as some tribes of miscrobei will not grow in horses, .or. indeed, s<s far as we know, in any animal except man. anti-toxins to neutralise Jheir poisons can be obtained only from the blood serum of convalescent human patients. Consequently the supply is extremely limited, it has not yet been stan dardised- and it canpot be procured commercially. Examples of these diseases are pneumonic influenza and infantile paralysis. Anti-tcxjns for both these diseases iftade from the blood of convalescent patients have been prepared and used with benefit in New Zealand hospitals. Numbers of convalescents, in this way, gener ously endeavour to benefit other sufferers —witness the splendid response during our' recent infantile paralysis epidemic. When a request was published in the newspapers for old infantile paralysis cases to voluntarily -camo to the hospital and donate some of their blood-serum in the hopes of benefiting the recently stricken, nearly every old infantile paralysis case in the cities offered him or herself to the hospital authorities. HOW ADMINISTERED. Though vaccines, toxins, and anti-toxins are on the sai .e footing as drugs, if they were given by th mouth most of them would be chemically altered and changed by digestive juices, and would not reach into the actual tissues at all. Therefoie, they have to be "ot direct into the tissues to escape digestion. Most are given under the skin or into the flesh with a hypodermic needle, but some can be slowly absorbed when made into an ointment and rubbed into the skin. Diphtheria and typhoid immunisinr preparations are given by the former method.- and recently some tuberculosis i munising preparations are being given by the ointment skin inunction methods. Anti-toxins are nearer always given hyno-’ mically. After circulating in the bloodstrtan. both toxins and anti-toxins are 'radually eliminated by the skin and kidneys, either in their chemically r ’tive form or after oxidation and chemical change. TRUE ACTIVE IMMUNITY.

The tr.-js of 1, oLgic-therapy follow three main lines. First, for some diseases it can be used to produce a • true active immunity, without übjecting the body to the dangers of an actual illness or invasionby living microbes, in our first article on immunity it was explained that,' though the ' uly-cells possessed inherently the power to manufacture nrotective substances, they would not rouse themselves to do so till stimulated thereto by the presence of (a) , microbes, or (b) their poisons circulating in the blood, but that this power, having been'once evoked, : mained active. Now our body-cells are on the whole not well able to discriminate between toxins and the microbes producing those toxins. If? therefore, one introduces into the blood-stream a suitable dose of sterilised standardised toxin or va cine, the body-cells immediately think they hare live microbes somewhere to deal, with. They proceed- to _put their inherent protective mechanism in action, they learn to manufacture anti-bodies and anti-toxins, and so a true .tive immunity is achieved, exactly similar 'tc the 'one produced in Nature by illness. , VERY SUCCESSFUL. '

The artificial production of active immunity by means Trf sterilised standardised toxins has been already an extraordinarily successful branch of preventive medicine. It is naturally more applicable to some diseases than to others. But at least two of -its triumphs are prettywell known to the general public. The reader is probably aware that preventive inoculation has already saved thousands or soldiers’ lives from typhoid, and thousands of- children from diphtheria. , . Secondly: Sometimes when the bodycells are too tolerant of a light, or specially a chronic microbe infection, and

will manufacture only enough anti-hodietf and anti-toxink to keep the disease processes fairly stationary, the introduction of a little more sterilised toxin will rouse, stimulate, or frighten the bodvcells into making a greater effort (if they have any reserves to call on), and producing enough anti-bodies to rweep the infection quite away.

Thirdly: For some diseases a passive temporary will either protectan individual temporarily against .bnormal risks of infection (as nurses in an epidemic), or can be used in an acute illness to neutralise tnicrobic poisons which are paralysing the body-cells and preventing them from making their own anti-bodies. For this purpose anti-toxins are used, not toxins which are seldom suitable for use in persons who are acutely ill. ~ -■

In diphtheria the use of anti-toxixns has reduced the mortality from 70 to 75 per cent, to 10 or 15 per cent. Tetanus anti-toxin was- extensively used in the war to prevent lockjaw, and anti-toxins have been even more successful in the treatment of hydrophobia.