7231
Analyses of mouse strains with congenital defects in different aspects of secondary lymphoid tissue development are beginning to clarify the role of these tissues in immune responses and host defense.
 None
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 None