TRAPANI 



The next point of information I wish to present is that of the im- 

 mune response of adrenalectomized animals. Even though there is 

 an abundance of literature dealing with the effect of the adrenal 

 steroids on various aspects of the immune response, little has been 

 done utilizing extirpation experiments. If the reaction of the animal, 

 deprived of its endogenous source of hormone, can be established, 

 then the activity of various available steroid preparations might be 

 more accurately assessed. 



Rabbits were bilaterally adrenalectomized ina one-stage opera- 

 tion (Zak, Good, and Good, 19 57) using a ventral mid- line approach. 

 They were maintained on 1 per cent saline for drinking water with 

 free access to food, and allowed to recover for 3 to 4 weeks before 

 being used in the experiments. Passive decay of antibody (Fig. 5) in 

 adrenalectomized rabbits was not significantly different from con- 

 trol animals. Active immunization (Fig, 6) shows an apparent net 

 decrease in the immune response of adrenalectomized rabbits. 



It has been reported that adrenal steroids depress the immune 

 response. The data presented here, however, indicate that adrenal- 

 ectomy results in a decreased immune response. These apparently 

 contradictory results present a paradox, and point to the complexity 

 of experiments of this kind. 



DISCUSSION 



The immune response can be thought of as composed of two 

 processes (antibody production and antibody dec ay) occurring simul- 

 taneously, but not necessarily at the same rate. It is possible to 

 measure the decay rate of passively administered homologous anti- 

 body; however, what is measured in the actively immunized animal 

 is the net result of antibody production and decay. It is conceivable, 

 therefore, that an increase in antibody production might be offset 

 by an increase in antibody decay so that the net level of circulating 

 antibody measured is apparently unchanged. 



98 



