202 CHEMISTRY OF THE IMMUNITY REACTIONS 



pendent upon saturation or exhaustion of all the anaphylactic anti- 

 bodies, and hence the amount of these antibodies present free in the 

 blood of a sensitized animal must be relatively small, for a few milli- 

 grams of the specific protein is sufficient to saturate them, e. g., the 

 amount of antibody present in 3 c.c. of serum from a guinea-pig sen- 

 sitized with horse serum could be neutralized with from 0.0005 to 

 0.01 c.c. of horse serum. ^^ They are, however, very persistent, re- 

 maining in guinea-pigs through the entire life of an animal sensitized 

 when young. They also pass from the mother to the fetus, conferring 

 a passive sensitization which, like passive sensitization from injection 

 of serum from a sensitized animal, is of relatively brief duration, 

 in contrast to the persistence of active sensitization.''- Anaphylactin, 

 like amboceptor, resists heating at 56° for one hour, and is salted out 

 from serum in the globulin fraction. ^^ It can be formed in animals 

 made leukopenic with thorium-X.^^ Friedberger contends that it 

 is identical with the precipitin, a view yet under discussion,''^'* but 

 strongly supported by Weil's observations.^^ 



WeiP^ observed certain phenomena which led him to conclude 

 that in anaphylaxis the specific antibody must be largely fixed in the 

 cells, and that it is in the cells that the reaction occurs; apparently 

 the antibodies present in the blood of the sensitized animal are insuf- 

 ficient to protect its cells from the foreign protein, hence the cellular 

 intoxication. In support of this idea is the observation of Dale" 

 that the isolated smooth muscle of sensitized guinea-pigs is specifically 

 sensitive to the foreign protein. Weil states that "all the evidence 

 proves conclusively that anaphylactic shock is induced by reaction 

 between anchored antibody and antigen, and that circulating anti- 

 body plays absolutely no role in its production." 



The anaphylactin shows quite the same characteristics of specificity 

 as the other immune antibodies,''^ in that proteins of closely related 

 species tend to interact, while proteins of very distinct biological or 

 chemical nature are easily distinguished. Thus, guinea-pigs sensi- 

 tized with ape serum will react with human scrum, but not with serum 

 from dog or ox or fowl. However, in the final analysis, the speci- 



6' Anderson and Frost, Jour. Med. Res., 1910 (23), 31. 



^2 The brief duration of passive sensitization presumably depends on the forma- 

 tion of antibodies for the foreign sensitizing serum, constituting the condition 

 of "antisensitization" as contrasted with the refrac^tory period which results from 

 the exhaustion of antibodies by antigen. (See Weil, Zeit. Immunitat., 1913 (20), 

 199; 1914 (23), 1.) • 



"^ However, Schiff and Moore state that in immune sera the albumin fraction 

 contains both the agent that confers passive sensitization ami the constituent 

 that causes the "primary toxicity" of foreign sera. (Zeit. immunitat., 1914 (22), 

 009.) 



" Corper, Jour. Infect. Dis., 1919 (25), 248. 



"■"•See Zins.ser, .Jour. l':xp. Med., 1912 (15), 529. 



"* Jour. Immunol., 1910 (1), 1. 



6« Jour. Med. Research, 1913 (27), 497; 1914 (30), 299-364; 1915 (32), 107. 



"Jour, rharm., 1913 (4), 107. 



08 See review in Jour. Infect. Dis., 1911 (S), 73. 



