Which immune response involves the formation of soluble antigen-antibody complexes?

The formation of soluble antigen-antibody complexes is characteristic of the precipitation reaction, which occurs when soluble antigens react with specific antibodies, resulting in a visible precipitate. This process is part of the broader humoral immune response, where antibodies are produced by B cells in response to antigens.

In this context, when soluble antigens are mixed with their specific antibodies, they form complexes that can aggregate and eventually precipitate out of the solution. This reaction is crucial in laboratory diagnostics and helps in the detection of various diseases.

The humoral response, while encompassing the precipitation reaction, also includes other aspects such as the production of antibodies and the activation of B cells, but the term "precipitation reaction" specifically refers to the formation of the complexes. Therefore, choosing the precipitation reaction accurately identifies the particular interaction that leads to complex formation, emphasizing its distinct role in immune responses.