Immunology

Chapter 43

Innate Immunity

Present and waiting for exposure to pathogens

Non-specific

External barriers and internal cellular and chemical defenses

Aquired Immunity

Specific

Develops after exposure

WBC’s involved in B and T cell immunity

Involve antibodies

Innate and Aquired Immunity

Innate Immunity – External Defenses

Skin

Mucous membranes

Cilia

Oil glands

Sweat glands

Stomach acid

Lysozyme in saliva, tears, and mucous

Innate Immunity – Cellular and Chemical Defenses

Phagocytosis

Antimicrobial proteins

Inflammation

Fever

Natural Killer Cells

Phagocytosis

Ingest invading organisms

Produce antimicrobial proteins and initiate inflammation

Ex: neutrophils, macrophages,, eosinophils, dendritic cells

Types of Phagocytes

Neutrophils- most abundant, ingest and destroy invadersMacrophages – found in spleen, lymphEosinophils – defend against parasites by secreting enzymesDendritic Cells – ingest microbes and are involved in development of aquired immunity

Lymph System Role in the Immune System

Antimicrobial Proteins

Complement system – composed of about 30 different microbial proteins which cause the lysis of the invading cell

Ex: interferon: fight against viral infections, secreted by virus infected cells that warn neighboring cells

Inflammatory Response

Heat, swelling, redness and pain

Caused by histamines that are released by damaged cells (cause vessel dilation)

Allows for more WBC and quicker clotting

Fever – allows for phagocytosis and increase killing of pathogen

Natural Killer Cells

Attack virus infected and body cells by releasing chemicals that cause cell death

Aquired Immunity

Humoral and cell mediated immunity

Macrophages secrete cytokines that activate the aquired immune system

Epitopes (antigenic determinants)

Antigen – molecule that causes an immune response, can be from a pathogen or another type of cell

Epitope – the antigentic determinant area, where the antibody will bond

Anitgen Recongition

2 types of lymphocytes (WBC’s) recongnize antigens – B and T cells

B cell have Y shaped molecules (AKA anitbodies or immunoglobulins) that are composed of 2 heavy chains and two light chains – the tips of the molecules are specific to different antigens (called the V region)

Anitbody Structure

T Cell Receptors

Recognize antigens that are bound to a normal cell protein called a MHC- major histocompatibility complexThe MHC binds with the antigen on the membrane of a normal cell – called antigen presentationClass I MHC – bind antigens of molecules formed in the cells (infected cells)- recognized by cytotoxic T cellsClass II MHC – bind antigens that have been internalized though phagocytosis (ex: dendritic cells and macrophages)- recognized by helper T cells

Lymphocyte Development

Lymphocytes that go to the thymus turn into T cells, while ones that develop in the bone marrow turn into B cells

When one of these cells encounters an antigen for the first time, it stimulates it activation and proliferation – call clonal selection

Lymphocyte Diversity

The specificity to antigens is vast

There are 1 million different V regions in B cells and 10 million different V regions in T cells all coded for by differential gene splicing

If a region is made that codes for one’s own body antigen it will be destroyed – this keeps self vs. non-self recognition

B and T Cell Development

Clonal Selection

Once a B or T cell has been activated it will form 2 clones

One clone will make effector cells (that will work to fight the antigen)

The other clone will make memory cells

Clonal Selection

Immunological Memory

Primary Immune Response – slow, must go through clonal selection

Secondary Immune Response – fast due to the presence of memory cells

Humoral Immunity

B cells

Make antibodies

Rely on helper T cells

Humoral Immune Response

Antibodies

Produced by B cells

5 different classes – differ only in their V regions

Bind to antigens causing viral neutralization, opsonization, or agglutination

Cell Mediated Immunity

Cytotoxic T cells - directly destroy certain cells or secretes chemicals that cause the destruction of cells

kill infected and cancerous cells

Rely on helper T cells

Humoral and Cell Mediated Activation

Continued…

Continued…

The Killing Action of Cytotoxic T Cells

Active and Passive Immunity

Active – permenant; caused by natural exposure or vaccines that lead to memory cells

Vaccine – weaken or dead pathogen

Passive – temporary; given through pregnancy, breast milk or anitbody injection

Self vs. Non Self

Blood Types

Organ Transplants

Blood Groups

Type O

Type A

Type B

Type AB

Rh Factor

Immune Diseases

Allergies

Autoimmune Diseases

Immunodeficiency Diseases ex: HIV/AIDS