The Immune System

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

Innate Immunity

Innate Immunity

Innate Immunity

Innate Immunity

Innate Immunity

Innate Immunity

Innate Immunity

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