T Cell Biology Class II Mhc bind to fragments arise from exogenous Ag Peptide recognized by CD4+ T-helper cells Do not directly kill cell cells enlarge and divide more CD4+ cells Secrete cytokines(such as IL2) either directly inhibit pathogen or recruit other cells for mmune response BIOL 533 Lecture 7BIOL 533 12 Lecture 7 T Cell Biology • Class II MHC bind to fragments arise from exogenous Ag • Peptide recognized by CD4+ T-helper cells • Do not directly kill cell – cells enlarge and divide more CD4+ cells – Secrete cytokines (such as IL2) either directly inhibit pathogen or recruit other cells for immune response