SERUM HKACTIOXS -') 1 1 



dilating antigen residue, causing the symptoms of serum sickne.ss. 

 In support of this von Dungern demonstrated the coexistence of 

 antigen and antibody in the blood stream of rabbits injected with 

 horse serum. Longcope and Rackemann (1918) detected pre- 

 cipitins for horse serum in the blood of patients suffering from 

 serum disease and believed they had detected a correlation be- 

 tween antibody production and serum sickness. Opposed to these 

 findings according to Harten and Walzer (1939) are those of 

 Coca (1932) that precipitins for horse serum may occur in man 

 without the development of serimi sickness and are not present 

 (Coca, 1933), (Tuft, 1933) in the blood of patients treated with 

 normal horse serum even though serum sickness develops. 



Davidsohn (1929, 1930, 1933) carried out an extensive investi- 

 gation of the titer of heterophile antibodies in the blood of in- 

 dividuals who had received injections of normal or immune horse 

 serum. He seems to think there is some relationship between the 

 heterophile antigen in horse serum and serum disease. Doubt is 

 cast upon such a conclusion by Powell, Jamieson and Kempf 

 (1935) who found that the removal of heterophile antigen from 

 horse serum did not alter its capacity to produce serum sickness. 

 Davidsohn (1938) has also called attention to an increase in titer 

 of /? isoagglutinin in patients developing serum sickness. There 

 was no significant increase noted in a agglutinins. 



Atopic reagins, according to Tuft and Ramsdell (1929), appear 

 irregularly in the blood of individuals receiving injections of 

 therapeutic horse serum. Doubt is cast upon their importance by 

 the irregularity of their occurrence and the lateness of their 

 appearance in many cases of serum sickness. 



Since Zinsser, Enders and Fotliergill apparently accept as fairly 

 well established the antigen-antibody theory of von Pirquet and 

 Schick, it would seem desirable to review and discuss the evidence 

 which they accept as justifying such a conclusion. This evidence 

 may be summarized as follows : 



(a) The proteins in the serum injected are antigenic. Hooker 

 (1923) described at least three antigenic fractions of horse serum. 



(b) The existence of an incubation period between the injection 

 of horse serum and the appearance of serum sickness. 



