Clinical Aspects of Allergy

By I. M. Allen, M.D.

Introduction.—The group of diseases now recognised to have some relation to allergy, or sensitivity, has for many years baffled all attempts of clinicians to relieve or cure them. At the very best they were relieved, and the measure of relief was problematical. It was recognised that any treatment applied to them was purely empirical, and was in no way specific or curative. It was understood that, however many theories of their causation were formulated, the essential underlying cause was missing, and, until that could be discovered, any scheme of diagnosis and treatment must be imperfect. As a result, the sufferer from hay fever looked forward to a martyrdom of from six weeks to six months each year, the sufferer from eczema was exposed to constant irritation, and the asthmatic acquired his enemy in early childhood and had it with him for the rest of his days—and nights.

In the middle of the nineteenth century, Salter, basing his conclusions upon purely clinical observations, gave some indication of the direction in which the specific causation of such conditions might be sought, but, apparently, his work was lost sight of, and, as late as ten years ago, writers were laying particular stress upon the so-called neurotic element as the essential factor in their etiology. The growth of bacteriology and the discovery of a specific microbic cause for such diseases as tuberculosis, anthrax and cholera developed the theory that all diseases were due in some measure to infection. Bacteriology has helped to determine the specific cause, and, in many cases, the specific prophylaxis and treatment of the large group of infectious and contagious diseases, but there for the time is ended its work in the development of the history of medicine. Endocrinology, investigations into metabolism, and dietetics are all adding something to the sum of specific etiology.

There is a risk, however, that, in attempting to fit in conditions with the main thesis of the prevailing theory, an important side-issue may be overlooked. The discovery of specific microbic causes for diseases led to an attempt to develop immunity to the offending organisms and, incidentally, to other types of poisons as well. This resulted in the accidental discovery of the phenomenon of anaphylaxis by Richet in 1902, and the explanation that it was due to the same mechanism as immunity, though producing and opposite result. However, in 1903, it was shown by Arthus that the phenomenon was produced by ordinary horse serum, and it was then explained that it had no connection with the specific poisons employed, but was due to the protein contained therein. The classical symptoms of anaphylaxis —asthma, vomiting and diarrhoea, and those of serum sickness—rashes, vomiting and joint pains—suggested some resemblance to well-known diseases, and the possibility that they might be anaphylactic phenomena.

There, for some twenty years, the matter rested, until the American school of investigators brought the suggestion into the realm of practical diagnosis and treatment. Though the cutaneous test was first mentioned by Blackley in 1873, to Chandler Walker and his school is due the credit of formulating a practical method of investigating the sensitivity of an individual to the various proteins to which he is exposed in the ordinary rough and tumble of life. The elaboration of the cutaneous test for sensitivity has provided a convenient method of finding the irritant or irritants responsible for the individual’s symptoms. This, in turn, has cleared the way for the specific treatment of such conditions as asthma, and, although, at present, the methods are not perfect, they show promise of success.