SESSILE AND HUMORAL ANTIBODIES 



225 



reversion of the test mice to an immune state after splenectomy. 

 If the observed phenomena are connected with immunological 

 enhancement, it must be postulated that under certain conditions 

 of immunization the spleen becomes an organ engaged pre- 

 dominantly in humoral antibody synthesis. Since we found that 

 adoptively transferred enhancing activity could be conveyed by 

 pooled spleen and lymph node suspensions in some test systems, 



5 10 20 30 40 



DAYS 



Fig. 2. Influence of splenectomy in C3H ^ hosts grafted sub- 

 cutaneously with AMT 3. 



splenectomy 



sham operation 



Fraction denotes number of mice still bearing tumours/total 



number in group. Tumour size is plotted as average diameter 



in mm. of group. 



it seemed of interest to examine in these hosts the effect of splenec- 

 tomy upon the growth of incompatible tumours. Fig. 2 illustrates 

 the growth curves of AMT 3 transplanted to sham-operated or 

 splenectomized CsHcJ. The mice in each group were subjected to 

 identical procedures, short of actual removal of the spleen in the 

 sham-operated group. After one week they were challenged 

 subcutaneously with a suspension of AMT 3 as previously 

 described. Reference to the figure shows that the removal of the 

 spleen had a protective effect upon the host. Fig. 3 illustrates 

 equivalent results obtained in BALB/c S challenged sub- 

 cutaneously with BP 8 after splenectomy or sham operation. It is 



