Which phase of the primary immune response is characterized by a decline in antibody titer?

The decline phase of the primary immune response is characterized by a decrease in antibody titer. During this phase, after the initial activation of B cells and subsequent production of antibodies, the immune system begins to regulate and lower the levels of antibodies that were generated in response to the antigen. This decline occurs after the plateau phase, where antibody levels peak. The decline is a natural part of the immune response, as the body strives to return to homeostasis once the antigen is cleared.

In summary, recognizing the decline phase is crucial for understanding how the immune system maintains balance following an initial response to a pathogen. This information is fundamental when discussing the dynamics of antibody production and the immune response as a whole.