-macrophages

-dendritic cells

-dendritic cells

-macrophages

-B cells or B lymphocytes

-made in bone marrow and develop in thymus

-CD4

-CD8 (killer T cells)

-carries cell surface protein CD4

-T helper cells

-differentiate into four main types of cells

-activate other cells

-interact with MHC molecules to stabilize interaction needed for effective T cell response

-MHC-II

-carries cell surface protein CD8

-cytotoxic T cells (killer T cells)

-effector cells that act against virus infected cells

-recognize virus antigen on cell surface and kill cell

-interact with MHC molecules to stabilize interaction needed for effective T cell response

-MHC-I molecules

-kill cells recognized as non-self

-pathogen phagocytized

-pathogen broken down in phagolysosome

-viral proteins synthesized in cytosol

-bacterial proteins degreaded in vesicles of antigen presenting cells

-pathogen degraded into peptide fragments

-peptides presented on cell surface

-viral peptides presented on MHC-I molecules

-MHC is assembled in endoplasmic reticulum

-all nucleated cells of body present antigen

-two polypeptide chains: 3 a chain domains, B2 chain

-binds short peptides (8-10 amino acids long)

-MHC-II present bacterial antigens

-assembled in endoplasmic reticulum

-two polypeptide chains: 2 a chains, B1B2 chain

-a1 and B1 chains create peptide-binding cleft

-peptide length not restrained (>13 aa)

 -present in hematopoietic cells

-one antigen binding site

-bind to short continuous amino acid sequences (peptides)

-peptides that stimulate T cells are only recognized when bound to MHC molecule

-does not react with large, intact antigens

-two antigen binding sites

-binds directly to antigen

-binds to surface of protein antigens

-not associated with MHC molecules