The Immune System
First lines of defense:
•Skin
•Mucus
•Stomach acid
•Digestive enzymes
Innate Immunity•Phagocytic cells–Leukocytes (“white cells”)
–Lymphocytes (“lymph cells”)
–Macrophages (“big eaters”)–Natural killer cells (attack infected or cancerous body cells)
Innate Immunity•Inflammation–Redness and swelling
•Interferon –Released by infected cells, signals neighboring cells to prepare for invasion
Acquired Immunity•Lymphocytes–B cells and T cells
•Antibodies –Immunoglobulins
Antigens are foreign molecules that elicit an immune response
Acquired Immunity
Antigens are foreign molecules that elicit an immune response.
Acquired Immunity
B cells have antigen receptors that recognize intact antigens.
B
Acquired Immunity
T cells have antigen receptors for fragments of antigens.
B T
Acquired Immunity
Each lymphocyte recognizes one and only one antigen.
B T
Acquired Immunity
•Lymphocytes are made in the bone marrow
•B cells mature in the bone marrow
•T cells go to the thymus before maturing.
Acquired Immunity
•Genes in lymphocytes are randomly, permanently rearranged to produce over ten million different antigen receptors
•The ones that react to “self” are destroyed.
Acquired Immunity
Two kinds of immune response:
Humoral
Defends against toxins or pathogens outside of cells
Cell-mediated or cytotoxic
Destroys infected cells, cancer cells, and transplanted cells
Acquired Immunity
Humoral Immune ResponseHere come the germs…
Humoral Immune ResponseHere come the germs…
Humoral Immune Response1. A macrophage or a dendritic cell engulfs one of the invading bacteria
Humoral Immune Response1. A macrophage or a dendritic cell engulfs one of the invading bacteria.
Humoral Immune Response2. The macrophage displays broken up bits of the antigen bound to a major histocompatibility complex (MHC).
Humoral Immune Response3. A helper T cell recognizes the antigen fragments and is activated
Humoral Immune Response3. A helper T cell recognizes the antigen fragments and is activated
Humoral Immune Response3. A helper T cell recognizes the antigen fragments and is activated
Humoral Immune Response3. A helper T cell recognizes the antigen fragments and is activated.
Humoral Immune Response4. A B cell also recognizes the antigen and binds to it
Humoral Immune Response4. A B cell also recognizes the antigen and binds to it
Humoral Immune Response4. A B cell also recognizes the antigen and binds to it.
Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
Humoral Immune Response5. An activated helper T cell binds to the B cell and secretes cytokines to activate it
Humoral Immune Response6. The activated B cell divides to make two kinds of cells:
Humoral Immune Response-Plasma cells make antibodies
Humoral Immune ResponsePlasma cells (effector cells) make antibodies
Humoral Immune ResponseMemory cells wait for the next invasion.
Humoral Immune Response7. Antibodies bind to antigens.
Humoral Immune ResponseThere are four ways that antibodies work:
Humoral Immune ResponseThere are four ways that antibodies work:
neutralization
Humoral Immune ResponseThere are four ways that antibodies work:
neutralization
Humoral Immune ResponseThere are four ways that antibodies work:
neutralization
Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
Humoral Immune ResponseThere are four ways that antibodies work:
agglutinization
Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
Humoral Immune ResponseThere are four ways that antibodies work:
compliment fixation
There are four ways that antibodies work:
opsonization
Humoral Immune Response
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Humoral Immune ResponseThere are four ways that antibodies work:
opsonization
Cell Mediated Immune Response
Cell Mediated Immune ResponseHere come the germs…
Cell Mediated Immune ResponseA cell is infected
Cell Mediated Immune ResponseA cell is infected
Cell Mediated Immune Response1. A cell is infected.
Cell Mediated Immune Response2. Antigens are displayed on the cell surface bound to MHC.
Cell Mediated Immune Response3. A cytotoxic T cell (“killer T cell”) binds to the antigens
Cell Mediated Immune Response3. A cytotoxic T cell (“killer T cell”) binds to the antigens
Cell Mediated Immune Response3. A cytotoxic T cell (“killer T cell”) binds to the antigens.
Cell Mediated Immune Response4. Binding activates the T cell, which releases lytic enzymes.
Cell Mediated Immune Response5. Lytic enzymes destroy the cell (“apoptosis”)
Cell Mediated Immune Response5. Lytic enzymes destroy the cell (“apoptosis”)
Cell Mediated Immune Response6. T cell can now attack other target cells.
Cell Mediated Immune ResponseCancer cells will also display antigens that bind with killer T cells.
Immunity in Health and Disease
Immunity in Health and Disease
Active vs. passive immunity.
Immunity in Health and Disease
Rejection of transplanted tissue
Immunity in Health and Disease
Rejection of transplanted tissue
Graft vs. host reaction.
Immunity in Health and Disease
Allergies
Immunity in Health and Disease
Autoimmune diseases
Immunity in Health and Disease
Immunodeficiency diseases