Fig. 3: Activation of a Naive T4-Lymphocyte by an APC
A naive T4-lymphocyte
uses its TCR and CD4 molecule to bind to a complementary shaped MHC-II molecule
with attached peptide epitope on an APC. This interaction, along with the
binding of co-stimulatory molecules such as CD40, B7, LFA-3, and ICAM-1 on
the APC with their complementary ligands on the T4-lymphocyte, activates the
naive T4-lymphocyte enabling it to differentiate into an effector T4-lymphocyte.