Class Notes (836,270)
Canada (509,735)
BMS 860 (17)
Radulovich (17)
Lecture 19

BMS 860 Lecture 19: Cancer Notes 19

6 Pages
Unlock Document

Biomedical Sciences
BMS 860

Lecture 19- Immune response in cancer Immune system • Immune system distinguishes self from non-self • Eliminates harmful non-self molecules and cells from the body • Antigen is any molecule recognized by the immune system • The skin, cornea and mucosa of the respiratory, GI, and GU tracts form a physical barrier that is the body’s first line of defense. • Breaching of anatomic barriers can trigger: o Innate immunity = does not require prior exposure to an antigen to be effective ▪ Responds immediately to an invader, non-specific ▪ Components include phagocytic cells, natural killer cells and polymorphonuclear leukocytes o Adaptive immunity= requires prior exposure to an antigen to be effective ▪ Takes time to develop ▪ Cell-mediated response (T cells) ▪ Humoral immunity (B cells) • hematapoietic stem cells come from bone marrow, and can become myeloid or lymphoid progenitor cell o Myeloid progenitor cell will produce cells in the innate system o Lymphoid progenitor cells produce cells for the adaptive system ▪ cellular- t lymphocyte creates helper t cells, regulatory, and cytotoxic cells ▪ Humoral- b lymphocyte matures into plasma cells and makes antibodies Humoral immunity- mediated by b cells • 2 major domains- constant (Fc) on the bottom, and variable domains (Fab) that bind to antigens on top • Variable domains generated through combinations of genes, protein binding domains will be variable and bind many antigens • Elimination of antibody coated cells occur in 3 steps: o neutralization- antibody prevents bacterial adherence o opsonization- antibody promotes phagocytosis o complement activation- antibody activates complement, which enhances opsonization and lyses some bacteria Antigen processing • Dendritic cells phagocytose antigenic particles • Particles are fragmented into oligopeptides by proteolysis within the endosomes formed by phagocytosis • endosome- membrane bound compartment inside eukaryotic cells • MHC class II molecules migrate from ER to the endosomes • MHC class II molecules bind oligopeptides and migrate to the surface • Antigen presenting cells are professionals/unprofessional o Professional cells are in the innate system- dendritic cells Activation of B cells and antibody production • Dendritic cells presenting antigens proceed to the lymph nodes • Present antigens to helper T(H ) cells with compatible t cell receptors that recognize oligopeptide antigen • THis activated and looks for a compatible B cell • B cell is activated, differentiates into plasma cell and begins to release antibody molecules that are capable of recognizing the oligopeptide antigen. Neutralization • antibodies can directly bind infectious particles, preventing viral absorption and bacterial adherence Opsonization: macrophages • Bacteria coated by antibody, macrophages will bind the antibodies at the constant region (Fc) and through phagocytosis it will destroy bacteria and antibodies in lysosomes Opsonization: NK cells • Antibody coated mammalian cell recognized, natural killer cells will bind to the constant region (Fc) of the antibody, release cytotoxic granules, causes lysis of targeted cell Complement activation • Complement proteins in plasma bind antibody-antigen complex, create membrane channels, makes holes in the plasma membrane, cause lysis and apoptosis Cellular immune response • Mediated by cytotoxic T cells (Tc or CTL) • instead of using antibodies, uses t cell receptors (TCRs) • CTLs recognize and kill other cells displaying certain antigens on their surface • CD8 positive markers • Begins with antigen presentation through MHCI, leads to activation of naïve CD8 t cells, proliferation, differentiation, recognizes infected cells, destruction o Naïve- have not seen antigen, need to be activated Antigen presentation: MHC I • All cell types can present synthesized proteins on their surface- ex. MHC I • Synthesized proteins are processed into oligopeptide fragments • Oligopeptides enter ER and bind to MHC class I molecules • MHC class I complexes are dispatched to the cell surface Activation of CTLs by dendritic cells • Dendritic cells andHT cells can activate CTL cells • dendritic cells can present MHC class I and II • Activated CTL cell recognize and bind antigens displayed by MHC class I molecules on the surfaces of many cell types throughout the body (infected or abnormal cells) Mechanisms of killing by CTLs • CTLs contain lytic granules in its cytoplasm (pink arrows) • When contact is made with targetted cell, granules release perforin • Perforin forms cylindrial channels in the PM of the target • Apoptotic cascade o CTLs express Fas ligand o FasL binds Fas receptor displayed by the targeted cell and triggers receptor trimerization o Activation of extrinsic apoptotic cascade by caspases Innate immune response: NK cells • Cells of innate immune response can recognize and attack foreign particles without prior exposure to these agents • Cells of innate immune response recognize characteristic molecular patterns that are present on the surfaces of infectious agents (or cancer cells) but are not displayed by normal cells • Natural killer (NK) cells are thought to be the first cells that attack cancer cells • NK cell releases IFN-g and recruits other immune cells to the site of the attack o spreads cytoplasm to initiate killing, causes fragmentation in cancer cells Immune tolerance • Immune system must distinguish self antigens vs. foreign presented antigens • During development of imm
More Less

Related notes for BMS 860

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.