L2: Activation of Lymphocytes

Question 1

Which cells are triggered to mature into plasma cells (that produce a specific kind of antibody)?

Answer 1

B cell

Question 2

Which cells become active through a series of steps and activate other immune cells by secreting lymphokines?

Answer 2

T cell

Question 3

Describe signal 1 for T Cell activation

Answer 3

The T cell receptor (TCR) on both CD4+ helper T cells and CD8+ cytotoxic T cells binds to the antigen as it is held in a structure called the MHC complex, on the surface of the antigen-presenting cell (APC). This triggers initial activation of the T cells.

Question 4

Describe signal 2 for T Cell activation

Answer 4

In addition to TCR binding to antigen-loaded MHC, both helper T cells and cytotoxic T cells require a number of secondary signals to become activated and respond to the threat. In the case of helper T cells, the first of these is provided by CD28. This molecule on the T cell binds to one of two molecules on the APC – B7.1 (CD80) or B7.2 (CD86) – and initiates T-cell proliferation