Immunity

“ In the second place we must keep clearly before us an important fact, the truth of which any chronological account of the development of the principle of immunity would easily demonstrate, namely, that with the advance of time and with the growth of that principle, the changes which took place in the different sorts of immunities were not simply those of degree, but essentially and principally those of kind. ”

“ Acquired immunity is a protection not belonging to the tissues of individuals naturally and as part of their constitution, but it is acquired during their lives as a further accomplishment, so to speak, of their tissues. ”

“ By immunity is meant non-susceptibility to a given disease, or to experimental inoculation with a given bacterium or toxin. The term must be used in a relative sense, and account must always be taken of the conditions present. Immunity.An animal may be readily susceptible to a disease on experimental inoculation, and yet rarely or never suffer from it naturally, because the necessary conditions of infection are not supplied in nature. That an animal possesses natural immunity can only be shown on exposing it to such conditions, this being usually most satisfactorily done in direct experiment. ”

“ Active Immunity.—By active immunity is meant that which is due to the actual introduction of the organism, or in some cases of its products. The term active is used because the body cells of the animal immunized perform the real work of bringing about the immunity as will be discussed later. ”

“ Immunity.—There is no doubt that adjustments often confer immunity from infection and contagion, but it is so difficult to strengthen every part of the body against every possible infection or contagion, and so uncertain that immunity really exists in a given case, that it is best always to assume the possibility of contagion and act accordingly. Adjustments following exposure to known contagion are always wise, but one may never know, if they succeed, that the patient might not have escaped without them. ”

“ II. Passive—due to the introduction of the blood serum of an actively immunized animal.
Immunity present in an animal and not due to human interference is to be regarded as natural immunity, while if brought about by man’s effort it is considered artificial. Those cases of natural immunity mentioned above which are common to divisions, classes, orders, families, species or races of organisms and to those few individuals where no special cause is discoverable, must be regarded as instances of true inheritance through the germ cell as other characteristics are. ”

“ I desire now to refer again to the subject of racial and species immunity for which the humoral factors of bacterial destruction afforded an imperfect explanation, in order that I may point out that the introduction of bacteria, incapable of causing infection, into immune species is followed by immediate phagocytic ingestion and destruction of the microorganisms. The rapidity and perfection of the phagocytic reaction in insusceptible animals are very impressive and might readily lead to the decision that they suffice to explain the resistance or immunity. ”

“ As recovery progresses these immunity substances continue to increase until at the termination of the disease they are present in quantities that suffice often, by a passive transfer to another individual, to protect other animals more certainly from an infection, or to terminate abruptly an infection already established in them. ”

“ In addition to its mechanical defenses against disease, the body shows a varying degree of immunity, or the power possessed by living organisms to resist infections. Immunity or resistance is the opposite of susceptibility. ”

“ The question of the value of preventive inoculation is, however, still an open one. So also are other applications of the principles of immunity, as the production of anti-sera for snake-venom, and for the irritant (and perhaps intoxicating) vegetable agent causing hay fever.
I have earlier in this lecture referred to methods of serum diagnosis depending on agglutination or solution of bacteria or on the precipitation of protein. Immunology has recently contributed to medicine another diagnostic method of great value. ”

“ The idea here presented is that the immunity is active if it is the result of a necessity for internal intellectual adaptation on the part of Innate Intelligence, and when this adaptation takes place there will be immunity from further attacks. That the passive immunity is produced by the introduction of antitoxins or serums taken from the bodies of animals in whose bodies these adaptative processes have taken place. ”

“ It is a fact that if the serum of an animal which has been rendered immune to a certain disease be injected into a susceptible animal, the same immunity can be produced temporarily in the second animal. ”

“ Immunity, as has already been stated, implies such a condition of the body that pathogenic organisms after they have been introduced are incapable of manifesting themselves, and are unable to cause disease. ”

“ Immunity is classed as natural, acquired and artificial. Natural immunity is that natural resistance of Innate Intelligence through the activity in the normal body whereby all invading organisms and poisons, as well as all the products of katabolism are excreted before they have an opportunity [Pg 183] to act upon the tissues or otherwise interfere with the vital processes in the body. ”

“ I have gone into these matters chiefly because the modern theoretical study of immunity during the last few years has, in general, attracted greater attention to the blood, and shown the important role which the different parts, properties, and capacities of the blood play in defending the organism against internal and external injurious agencies. ”

“ Ways of detecting adulteration in foods, particularly foods from animal sources, and of differentiating proteins of varied origin, as well as means of establishing biological relationships and differences among groups of animals through “immunity reactions” of blood serums have followed from knowledge gained by application of the facts or the methods of immunity research. Hence the study of “immunity problems” has come to include much more than merely the study of those factors which prevent the development of disease in an animal or result in its spontaneous recovery. ”

“ But what permits a healthy body to resist its invasion by morbid organisms? What gives several animals immunity against certain special diseases? Why do rats resist anthrax, and dogs and monkeys resist the tuberculosis of fowls, while the same microbes are fatal to rabbits and guinea-pigs? And how can immunity against certain diseases be acquired either by vaccination or by previously having suffered the same disease? We know the microbes ”

“ Serum-therapy.— Novy and Knapp have proved that active immunity follows recovery from spirochæte infection, and that this immunity can be increased to a remarkable degree by successive injections of spirochæte-infected blood. They have further shown that passive immunity can be imparted by the injection of recovered or of hyperimmunized blood, and that both active and passive immunity persist for months. Preventive inoculations have been successfully practised in rats, mice, and monkeys. ”

“ There are some diseases in which there is little reason for thinking that any immunity is acquired, as in the case of tuberculosis, while there are others in which the immunity is very great and very lasting, as in the case of scarlet fever. Moreover, the immunity differs with individuals. While some persons appear to acquire a lasting immunity by recovery from a single attack, others will yield to a second attack very readily. ”

“ IMMUNITY.
It is evident, however, that it will take a long course of education and almost revolution in the sentiment of the people, to establish a system of segregation and quarantine as rigid and as perfect as that which is outlined. What then is the next best resort? I answer immunization. If we cannot keep the infectious organism from contact with the human body, we should endeavor to make the body immune from its ravages. ”

“ Probably the most enduring immunity is in smallpox, although cases are known of two and even three attacks; the immunity is high in scarlet fever, measles, mumps and typhoid fever. The immunity from diphtheria is short, and in pneumonia, although there must be a temporary immunity, future susceptibility to the disease is probably increased. In certain cases the immunity is only local; the focus of disease heals because the tissue there has evolved means of protection from the parasite, but if any other part of the body be infected, the disease pursues the usual course. ”

“ Many people may insist that this immunity or comparative immunity to tuberculosis and increased resistive vitality against the disease is transmitted and illustrates the principle of heredity. The reaction of the system to the disease increases in each generation and this increase is an acquired character which passes down with the family strain. This immunity should be viewed from another standpoint, however. Certain families possess a resistive vitality to the disease; others lack it. The resistant families do not succumb to it, and propagate themselves. ”

“ If these three defensive processes given us by Nature are in working order, that is to say, if we are "healthy," they should secure to us a sufficient "immunity"—at [Pg 244] at any rate, "recovery"—from any attack of disease-producing microbes. But they are not in "unselected," widely ranging mankind always equal (in their unaided natural state) to their task.
The attempts to produce immunity by vaccination with weakened or localised disease germs is really an attempt to train and develop to a high point the activities of the phagocytes or eater-cells of the blood. ”

“ The child that sleeps in the open and eats an abundance of pure, wholesome foods and takes a proper amount [Pg 85] of exercise, will escape most of the diseases of infancy and grow into manhood with a body immune to almost every infectious germ. I need not go into detail in regard to the actual mechanism of immunity to prove the fact that a well-nourished body, sustained by blood of high nutritious power and bearing its untold millions of organisms, armed cap-a-pie to destroy intruders, is a sufficient illustration of immunity. ”

“ THE term natural immunity is used to denote natural resistance to some particular specific disease. It may refer to race, or age, or individual idiosyncrasies. We not infrequently meet with examples of this freedom from disease. Certain races of men do not, as a rule, take certain diseases. For example, plague and leprosy, though endemic in some countries, fail to get a footing in England. ”

“ The question of immunity is of such great importance, the mechanism of this phenomenon and the physiology of intracellular digestion are so complicated, that I have thought it useful to epitomise here the exposition given of it by Metchnikoff in his book. Readers who do not care to go further into the subject can pass over the next few pages without hindering their comprehension of the following chapters.
Diseases affect all living beings, and the greater number of plants and animals would cease to exist without innate or acquired immunity. ”

“ Diseases which produce a general infection of the whole system are, as a rule, more likely to give rise to a lasting immunity than those which affect only small parts. Tuberculosis, which, as already noticed, is commonly quite localized in the body, has little power of conveying immunity, while a disease like scarlet fever, which affects the whole system, conveys a more lasting protection. ”

“ Ordinary cleanliness, good vitality, clean blood and tissues, the organs of elimination in good, active condition and, last but not least, a positive, fearless attitude of mind will practically establish natural immunity to the inroads and ravages of bacteria and disease taints. If infection takes place, the organism reacts to it through inflammatory processes, and by means of these endeavors to overcome and eliminate microorganisms and poisons from the system. ”

“ To be able to resist the invasion of any species of bacteria, one is said to be refractory to or immune against that variety of germs.
Serum therapy is based on the demonstrated fact of immunity, and of the possibility of producing it by injecting the serum of immunized animals. In many infectious diseases, one attack protects an individual for a lifetime and one form of disease may protect against even a more virulent form, as vaccination protects against smallpox. ”

“ Doubtless, also, some of the gland cells in the body have a corresponding action; statements which, if true, tend to emphasize the possible proteid nature of the protective substances.
While in a general way we may say that the natural immunity to certain bacteria possessed by some animals is due in large measure to an inhibition of the growth of the micro-organism, it must also be remembered that there is in many species a distinct immunity to the action of the poison which the specific micro-organism produces. ”

“ And our bodies have had the assistance of medical science, real medical science. Everyone knows how, after certain illnesses, immunity to that disease can be acquired. And more than blood fractions are involved in the process. ”