Understanding the Primary Response of Humoral Immunity: Key Processes and Roles of B Cells

All of the following are true of the primary response of humoral immunity except that A) it depends on antigen triggering the appropriate B cell.B) it requires B cell differentiation into plasma cells.C) it depends on memory B cells.D) circulating antibodies undergo a gradual, sustained rise. E) it peaks 1 to 2 weeks after the initial exposure.

The correct answer is C) it depends on memory B cells

The correct answer is C) it depends on memory B cells.

The primary response of humoral immunity is the initial response of the immune system to an antigen. It involves several processes that lead to the production of antibodies by B cells and their subsequent release into the bloodstream.

A) It depends on antigen triggering the appropriate B cell: During the primary response, a specific antigen binds to and activates a B cell that has a matching receptor for that antigen. This triggers the B cell to start dividing and proliferating.

B) It requires B cell differentiation into plasma cells: The activated B cells differentiate into plasma cells, which are antibody-producing cells. These plasma cells produce and release antibodies specific to the antigen that triggered the response.

C) It depends on memory B cells: This statement is not true. Memory B cells are formed during the primary immune response but are primarily involved in the secondary immune response. Memory B cells “remember” the specific antigen encountered during the initial exposure, allowing for a more rapid and efficient response if re-exposure to the same antigen occurs later.

D) Circulating antibodies undergo a gradual, sustained rise: During the primary immune response, the production of antibodies by plasma cells gradually increases and reaches a peak. However, this rise is not gradual and sustained. It is initially slow, but once activated B cells start differentiating into plasma cells, antibody production increases more rapidly.

E) It peaks 1 to 2 weeks after the initial exposure: During the primary response, the peak of antibody production typically occurs 1 to 2 weeks after the initial exposure to the antigen. This time is required for the activation, proliferation, and differentiation of B cells into antibody-producing plasma cells.

So, the correct statement should be that the primary response of humoral immunity does not depend on memory B cells. Memory B cells play a crucial role in the secondary response, allowing for a faster and more effective response upon re-exposure to the same antigen.

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