During a measles epidemic, a country introduced measles vaccination. It was later found that children who had been vaccinated were more likely to survive childhood than children who had not been vaccinated, even in years when there were no measles epidemics. The vaccine had provided the children with some defence against other pathogenic infections. Which statement could explain this additional protection?
- AB-lymphocytes produced memory cells which gave the children passive immunity to these infections.
- BMemory cells produced plasma cells which secreted anti-measles antibodies that bound to antigens that closely resembled measles antigens.
- CMemory cells produced plasma cells which secreted anti-measles antibodies that bound to any antigen.
- DT-lymphocytes produced memory cells which gave the children natural immunity against these other infections.