Which of the following is a characteristic of the primary immune response?

• A. It has a longer lag phase before antibody production begins.
• B. It relies primarily on memory cells for antigen recognition.
• C. It generates a rapid and robust antibody response upon first exposure.
• D. It produces mainly IgG antibodies initially.

Answer: (A)

Verified step by step guidance

1. Understand that the primary immune response occurs when the immune system encounters an antigen for the first time.
2. Recall that during the primary response, naive B cells are activated, which takes time to recognize the antigen and proliferate, leading to a lag phase before antibodies are produced.
3. Recognize that memory cells are not involved in the primary response because they are generated after the first exposure; memory cells are important in the secondary response.
4. Note that the antibody production in the primary response is slower and less robust compared to the secondary response, which is rapid and strong due to memory cells.
5. Remember that the first antibodies produced in the primary response are mainly IgM, not IgG, which appears later or in subsequent responses.