Question

If a person is sick with the common cold on May 1st, gets well, and then memory cells are exposed to the same virus on May 31st, what would the person's symptoms most likely be?

• Same symptoms as on May 1st

• More severe symptoms as the colds "piggy back" on each other

• Mild common cold symptoms

• No symptoms at all

• Flu-like symptoms

Answer 1

D. No symptoms at all

• Memory cells are specialized type of immune cells (differentiated form of B and T cell) that are used during secondary immune response. They act faster and are thus able to kill invading pathogen faster.
• They are formed during primary immune response (first exposure) and are activated during subsequent invasion by same pathogen again (secondary response)
• Moreover the antibodies (especially IgG) formed during first exposure are long lasting and therefore they will also mount immune response
• Both these factors ensures that if pathogen attacks next time then it will be killed immediately. Therefore there won't be any symptoms.