Which of the following correctly describes what happens after a vaccine is administered?
- A. memory cells are destroyed to reset the system
- B. the antigens multiply and cause the full disease
- C. the vaccine replaces the plasma proteins
- D. antigens stimulate lymphocytes, producing plasma cells and memory cells
Explanation
The weakened or dead antigens cannot cause disease but are presented to lymphocytes, which respond exactly as in infection, leaving memory behind. This controlled rehearsal is the entire principle of vaccination.