The Immunological Relationship of Hordein of Barley and Gliadin of Wheat as shown by the Complement Fixation, Passive Anaphylaxis, and Precipitin Reactions. The Biological Reactions of the Vegetable Proteins. IV

OF PROTOCOLS. Experiment i.-Gliadin, wheat. During a period of 23 days a rabbit was given six intravenous injections containing in all I. 2 gmin. of gliadin dissolved in o. I per cent r See preceding paper, II, Jour. Infect. Dis., 1913, I2, p. 341. 368 G. C. LAKE, T. B. OSBORNE, AND H. G. WELLS NaOH, but it died suddenly immediately after the last injection. (In all our experiments the vegetable protein solutions were prepared just before injecting.) Blood drawn on the sixteenth and twenty-third days gave no precipitin reaction with wheat gliadin in dilutions varying from I1-400 to I-4,000ooo. Experiment 2.-Gliadin, wheat. A rabbit received during the course of 7 weeks io intravenous injections, containing in all 2 gmi. of gliadin dissolved in o. I per cent NaOH, the dates of the injections being as follows: February 13, 19, 23, and 26, March I, 8, 9, and 22, and April I and io. The rabbit died on April 30 in poor condition. Precipitin tests were made with dilutions of 1-400 up to 1-400,000, but negative results were obtained with blood drawn on the following dates: March I, 8, and 16. Complement fixation tests were made on April I3, and positive reactions obtained with dilutions of I1-400 to I-4,00ooo, the only dilutions tried. Passive anaphylaxis experiments were tried on April 16 and 23; each time 3 guinea-pigs were given an intraperitoneal injection of the rabbit's blood (from I to 3.5 c.c. to each animal), but none of these animals reacted to gliadin injected 48-72 hrs. later. Experiment 3.-Gliadin, wheat. During 27 days a rabbit received 8 intraperitoneal injections containing a total of 4.7 gm. of wheat gliadin dissolved in o. I per cent NaOH, spaced as follows: June I9, 24, 27, July i, 5, 8, and 15. On July 22 blood was drawn and the complement fixing power determined. Positive reactions were obtained with wheat gliadin in dilutions up to i-io,ooo. Negative results were obtained with hordein and rye gliadin in dilutions of 1-2,000ooo. As another rabbit at this time was furnishing a serum of much higher power, nothing further was done with this animal. Experiment 4.-Gliadin, wheat. A rabbit received injections containing gliadin on the same dates and with the same amounts as in Experiment 3. Ten days after the last injection it was bled to death, and the serum used for experiments. On July 22 a sample of blood was drawn and found to give a positive complement fixation reaction with wheat gliadin in a dilution of i-ioo,ooo, while negative reactions were given with hordein, rye gliadin, wheat "proteose," and malt "proteose" in dilutions of 1-2,000ooo. Positive complement fixation was given with wheat gliadin on July 29, with dilutions of 1-20o,ooo000, while no reactions were obtained with the above-mentioned heterologous proteins at 1-2,000ooo. (More concentrated solutions cannot be used safely as a routine practice, because stronger solutions of these vegetable proteins often yield precipitates with serum, but occasionally, as will be noted, we have been able to make tests with strengths as great as 1-400.) Precipitin tests were made with this serum, but no precipitin reaction was obtained with wheat gliadin in a dilution as low