Question

In order for the adaptive immune response to be initiated, what has to happen first?

Answer 1

The first step in initiating the adaptive immune response is the activation of B or T lymphocytes by antigens.

Step-by-step explanation:

The first step in initiating the adaptive immune response is the activation of B or T lymphocytes by antigens.

1. For B cells, antigen activation occurs when a B cell encounters its matching antigen, engulfs it, and displays fragments of the antigen on its surface.
2. This attracts a helper T cell, which binds to the B cell at the antigen site and releases cytokines that signal the B cell to develop into a plasma cell.
3. For T cells, antigen activation occurs when an antigen-presenting cell (APC) displays antigens on its surface via major histocompatibility complex (MHC) molecules, and complementary naïve T cells recognize the antigens.

These steps are crucial in initiating the adaptive immune response and mounting an effective defense against pathogens.