IMMUNITY IN EXPERIMENTAL INFECTIONS 129 



Importance of Antibodies. — More recently Gay and Clark 

 (1930)* have offered experimental evidence indicating that anti- 

 Ijodies enhance the cellular defensive mechanism. In their opinion 

 the reason that antibacterial, e.g., antistreptococcal immune serum, 

 fails to combat a streptococcus infection is not a lack of antibodies 

 but an absence of mobilization of clasmatocytes in the patient. 

 They found that "in the case of experimental streptococcus 

 empyema in the rabbit the course of the ordinary fatal infection 

 is in no wise affected by the transfer of the pleural fluid contain- 

 ing large numbers of mononuclear cells derived from an animal 

 that is protected as a result of nonspecific irritation. The serum 

 of a rabbit highly immunized against the streptococcus and con- 

 taining antibodies for it, produces relatively slight effect in pre- 

 vention or cure. ' ' 



Passive Immunization With Pleural Exudate. — "In contrast 

 to this the pleural exudate, either acute (polymorphonuclear) or 

 subacute (mononuclear) produced in an actively immunized 

 animal does protect passively to a considerable degree. In a similar 

 fashion normal exudate cells of either type in combination with the 

 relatively ineffective antiserum give a high degree of protection." 

 In other studies Gay and Oram (1931) report that clasmatocytes 

 are much more resistant to Streptococcus leucocidin than the neu- 

 trophils. They regard this as further evidence of the superiority 

 of "tissue macrophages" over neutrophiles in combating strepto- 

 coccus infections. 



Experimental Staphylococcus Infections in Guinea Pigs. — In 

 regard to tissue resistance to staphylococcus infections Freedlander 

 and Tooiney (1928) have studied nonspecific mechanisms and Can- 

 non et al. specific factors in the skin of guinea pigs. The former 

 compared the inflammatory response in the subcutaneous tissues of 

 normal guinea pigs with the response in guinea pigs whose skins 

 had been treated with nonspecific irritants. They observed that 

 the latter were protected for short periods of time by tissue 

 macrophages mobilized by nonspecific irritation. 



Cannon et al. (1930, 1932) have investigated tissue immunity to 

 staphylococcus infection in normal and vaccinated guinea pigs. 

 They find that when staphylococci are injected into the skin of the 

 abdominal wall of normal guinea pigs there results an inflammation 



•Gay, F. P., and Clark, A. R. : J. Exper. Med. 52: 94, 1930. 



