A person is exposed to antigen X, and 3 weeks later to antigen X again and antigen Y for the first time. Compared with the response to the first exposure to X, the response to Y will have:
Answer and explanation
Correct answer: C. A similar lag time and peak to the first response to X, as no memory cells for Y exist yet
- Step 1: Memory cells are specific to the antigen that formed them, so X memory cells do not recognise Y.
- Step 2: Y therefore gives a primary response, like the first response to X, while the repeat of X gives a faster, larger secondary response.
Answer
a primary-type response for Y.
Why not the others: Memory for X does not carry over to Y; plasma cells for X make only anti-X antibodies; the system can respond to both antigens together.
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