An immune response begins when a ________ is activated by binding to both a foreign antigen and a self antigen on an antigen presenting cell's plasma membrane.

Question

Quizplus · Accepted Answer

The activation of helper T lymphocytes is the starting point of an immune response. Helper T lymphocytes recognize a foreign antigen presented by an antigen-presenting cell (APC) on its plasma membrane, along with a self-antigen, through the T-cell receptor (TCR) and co-stimulatory molecules such as CD28. This recognition leads to the activation and proliferation of helper T lymphocytes, which then activate B lymphocytes and killer T lymphocytes to mount an immune response against the foreign invader. Plasma cells are the effector cells that produce antibodies, and B lymphocytes are activated by helper T lymphocytes to differentiate into plasma cells. Killer T lymphocytes are also activated by helper T lymphocytes to recognize and kill infected host cells.

An Immune Response Begins When a ________ Is Activated by Binding