308 IMMUNOLOGY 



eoccus or antimeningoeoccus sera. Mild sensitization may occur 

 from the small amount of horse serum in toxin-antitoxin mixtures 

 used in immunization (Hooker, 1924; Tuft, 1932). To avoid the 

 latter source of sensitization, the manufacturers of T.A.T. are 

 using antitoxin obtained from goats, thus avoiding the inclusion of 

 horse serum in the mixture. Park's experience was quite exten- 

 sive and extremely valuable. He found that the history of a previ- 

 ous injection of horse serum is not a contraindication to the use 

 of antitoxin properly administered. As previously stated statis- 

 tical studies show that fatalities, when they occur, follow the first 

 rather than the second injection of horse serum, and tlius would 

 come under the first three groups mentioned above. 



Since tlie introduction of antipneumococcus rabbit serum by 

 Ooodner, Horsfall and Dubos (1937) there has been a growing in- 

 terest in acquired hypersensitiveness to rabbit serum. AVhile 

 Horsfall, Goodner, MacLeod and Harris (1937) suggest the use of 

 an intravenous test to detect allergy to rabbit serum, Warner 

 (1939) and also MacLeod (1939) conclude that it should not be 

 tried until the cutaneous and ophthalmic tests are made and found 

 negative. 



In the modified intravenous test 0.01 c.c. of a 1 :10 dilution in 

 5 c.c. of saline is used for slow intravenous injection. A positive 

 reaction is indicated if during the period of five minutes after 

 administration there is a drop in the blood pressure of 15 mm. of 

 mercury and an increase in heart rate of 15 beats per minute. 



The ophthalmic test consists in putting a drop of undiluted or 

 diluted serum in the eye of the patient. It indicates mucous 

 membrane sensitivity and may be negative when the skin test is 

 positive. Rarely is the reverse true. If the skin tests are negative 

 or weakly positive, undiluted serum may be employed for the 

 ophthalmic test but when the skin test is strongly positive dilutions 

 of 1:10 or 1:100 should be employed according to Tuft (1937). 



Brown (1938) and also Walzer (1939) report that rabbit serum 

 is not irritating to the skin and therefore properly performed 

 intracutaneous tests do not yield too many nonspecific reactions. 

 They suggest using 0.01 c.c. of a 1 :100 or 1 :10 dilution of normal 

 rabbit serum for the intracutaneous test. The ophthalmic test is 

 said to be negative frequently in acquired hypersensitiveness to 



