APC Activates T cell Posted by Shayna Matson Full size 914 × 736 pixels Playdoh Model for Antigen Presenting Pathway and Immunodominance 7. The leftover peptides exit the APC while the selected peptide from the HA is used to activate the CD4+ T cell. This step initiates the adaptive immune response. Previous image Next image Leave a Reply Cancel replyYour email address will not be published. Required fields are marked *CommentName* Email* Website Save my name, email, and site URL in my browser for next time I post a comment. Δ