Clinical and experimental studies in allergy

Abstract

Few branches of medical science hold promise of a richer harvest or are burdened by more conflicting theories and speculations than that of Allergy. Some of the confusion is due to the multiplicity of terms employed for the various types of allergic phenomena and to the different interpretations of the same term by clinicians and pathologists. Von Pirquet defined allergy as the altered capacity for reacting which follows disease or treatment with a foreign substance. Though von Firquet had in mind particularly the hypersensitivity of infection and serum disease he appears to have included spontaneous hypersensitivity of the hay fever type as well. As his original definition did not specify the direction in which the change of reactivity takes place, the term may be taken to include all acquired immunity in addition to hypersensitivity. By investing the term allergy with such an all -embracing meaning the word in itself conveys but little, or rather its vastness prevents any attempt at a precise definition. In contrast to the fundamentalist view is the tendency, due mainly to Americian clinicians, to narrow down the meaning of the term to designate the hypersensitivities of the asthma -hay fever -eczema -urticaria group. This latter interpretation, however, does not help matters much, as the term allergy has been firmly established by pathologists in connection with the hypersensitivity of infection in man and animals, the mechanism of which is of a different nature to that of the asthma group. One may cite the case of the indignant doctor from Ohio, who, wishing to pour forth his views on asthma, had come all the way to a 'Congress of Allergy' in London to do so, only to find to his disgust "Frenchmen and Germans talking about tuberculosis" (Freeman). Attempts to avoid this ambiguity have resulted in a flood of terms to describe the asthma group; thus we have, to mention but a few, Atopy (Coca), Hyperergy (Schick), Attack Diseases (Aschoff), and Toxic Idopathies (Freeman). The tendency of many in the profession to -day is to extend the popular American usage and apply the term allergy to all those conditions in man which are believed to be expressions of a state of increased reactivity, irrespective of the nature of the mechanism by which they are actuated. Indeed, I recently heard a distinguished physician describe as allergic the lowered tolerance to morphia found in patients with disease of the liver.The conception of allergy in the general sense of increased reactivity is being widely, and at times wildly, applied to medical problems at the present time. I feel that much of the confusion and conflict of opinion, especially marked in connection with the hypersensitivity of infection and its relationship to infective and non -infective asthma on the one hand and to antibacterial immunity on the other, is due to a failure to realize that in the group of phenomena designated . allergic there are several different types of immunological mechanism involved. In bacterial allergy, for example, evidence has already been presented to show there are at least three independent types of allergy to the pneumococcus and its products, of which one type is closely related to antipneumococcal immunity.The investigations here -in described were carried out in the Laboratories of the Inoculation Department, St. Mary's Hospital, London, during the tenure of an Asthma Research Council Fellowship, 1932 -1939.