CHAPTER II

SENSITIZATION TO PROTEIN FOODS

The first introduction under the skin of a guinea-pig of a minute quantity of egg-white or other apparently harmless protein substance is itself without visible injurious effect, but if this is followed by a second injection of the same substance after an interval of about ten days, the animal will die in a few minutes with symptoms of violent poisoning. Whatever be the physiological explanation of the remarkable change that thus results from the incorporation of foreign protein into the body, there can be no doubt that the phenomenon known as protein sensitization or anaphylaxis is relatively common.[2] Sensitization to proteins came to light in the first instance through the study of therapeutic sera, and has been found to have unexpectedly wide bearings. It is now known that not only the rash and other symptoms which sometimes follow the administration of horse serum containing diphtheria antitoxin, but the reaction to tuberculin and similar accompaniments of bacterial infection, are probably to be explained on the principle of anaphylactic change. The sensitiveness of certain individuals to the pollen of particular plants (hay fever) is also regarded as a typical instance of anaphylaxis, accompanied as it is by asthma and other characteristic manifestations of the anaphylactic condition.

Among the reactions usually classed as anaphylactic are the occasional cases of sensitivity to particular food substances. It is a familiar fact that certain foods that can be eaten with impunity by most persons prove more or less acutely poisonous for others. Strawberries and some other fruits and some kinds of shellfish are among the articles of food more commonly implicated. Unpleasant reactions to the use of eggs and of cow's milk are also noted. The severity of the attacks may vary from a slight rash to violent gastro-intestinal, circulatory, and nervous disturbances.

Coues[3] has described a rather typical case in a child twenty-one months old and apparently healthy except for some eczema. When the child was slightly over a year old egg-white was given to it, and nausea and vomiting immediately followed. About eight months later another feeding with egg-white was followed by sneezing and all the symptoms of an acute coryza. Extensive urticaria covering most of the body also appeared, and the eyelids became edematous. The temperature remained normal and there was no marked prostration. The symptoms of such attacks vary considerably in different individuals, but usually include pronounced urticaria along with nausea, vomiting, and diarrhea. The rapidity with which the symptoms appear after eating is highly characteristic. Schloss[4] has reported a case of an eight-year-old boy who evinced marked sensitiveness to eggs, almonds, and oatmeal. Experiments in this instance showed that a reaction was produced only by the proteins of these several foods, and that extracts and preparations free from protein were entirely inert. It was further found that by injection of the patient's blood serum guinea-pigs could be passively sensitized against the substances in question, thus showing the condition to be one of real anaphylaxis.

Idiosyncrasy to cow's milk which is observed sometimes in infants is an anaphylactic phenomenon.[5] The substitution of goat's milk for cow's milk has been followed by favorable results in such cases.

In very troublesome cases of protein idiosyncrasy a method of treatment based on animal experimentation has been advocated. This consists in the production of a condition of "anti-anaphylaxis" by systematic feeding of minute doses of the specific protein substance concerned.[6] S. R. Miller[7] describes the case of a child in whom a constitutional reaction followed the administration of one teaspoonful of a mixture composed of one pint of water plus one drop of egg-white, while a like amount of albumen diluted with one quart of water was tolerated perfectly. "Commencing with the dilution which failed to produce a reaction, the child was given gradually increasing amounts of solutions of increasing strength. The dosage was always one teaspoonful given three times during the day; the result has been that, in a period of about three months, the child has been desensitized to such an extent that one dram of pure egg-white is now taken with impunity."

Many other instances of anaphylaxis to egg albumen are on record.[8] In some of these cases the amount of the specific protein that suffices to produce the reaction is exceedingly small. One physician writes of a patient who "was unable to take the smallest amount of egg in any form. If a spoon was used to beat eggs and then to stir his coffee, he became very much nauseated and vomited violently."[9]

The dependence of many cases of "asthma" upon particular foods is an established fact. Various skin rashes and eruptions are likewise associated with sensitization to certain foods.[10] McBride and Schorer[11] consider that each particular kind of food (as tomatoes or cereals) produces a constant and characteristic set of symptoms. Possibly certain definitely characterized skin diseases are due to this form of food poisoning. Blackfan[12] found that of forty-three patients without eczema only one showed any evidence of susceptibility to protein by cutaneous and intracutaneous tests, while of twenty-seven patients with eczema twenty-two gave evidence of susceptibility to proteins.

FOOTNOTES:

[2] General agreement respecting the true physiological and chemical nature of anaphylactic phenomena has not yet been reached. For a discussion of the theories of anaphylaxis, see in Hans Zinsser, _Infection and Resistance_ (New York, 1914), chaps. xv-xviii; also Doerr, "Allergie und Anaphylaxis," in Kolle and Wassermann, _Handbuch_, 2d edition, 1913, II, 947.

[3] _Boston Med. and Surg. Jour._, CLXVII (1912), 216.

[4] _Amer. Jour. Obstet._ (New York), LXV (1912), 731.

[5] F. B. Talbot, _Boston Med. and Surg. Jour._, CLXXV (1916), 409.

[6] See, for example, Schloss, _loc. cit._

[7] _Johns Hopkins Hosp. Bull._, XXV (1914), 78.

[8] See, for example, K. Koessler, _Ill. Med. Jour._, XXIII (1913), 66; Bronfenbrenner, Andrews, and Scott, _Jour. Amer. Med. Assoc._, LXIV (1915), 1306; F. B. Talbot, _Boston Med. and Surg. Jour._, CLXXI (1914), 708.

[9] _Jour. Amer. Med. Assoc._, LXV (1915), 1837.

[10] Strickler and Goldberg, _Jour. Amer. Med. Assoc._, LXVI (1916), 249.

[11] _Jour. Cutaneous Dis._, XXXIV (1916), 70.

[12] _Amer. Jour. Dis. of Children_, XI (1916), 441.