Specific Defense Mechanisms

Antibody Classes

1. IgA 2. IgM 3. IgD 4. IgE 5. IgG

Components of Immune System

1. Thymus 2. Bone Marrow 3. Lymph nodes 4. Lymphatics 5. Spleen

Allergen

Antigen which provoke an allergic response (IgE)

Epitopes

Antigenic determinants Specific regions of an antigen to which Antibody reacts

Immunogens

Antigens which evoke an antibody response (other than IgE)

Antibodies

Globulin proteins produced in response to an antigen

Duality of the Immune System

Humoral and cell mediated responses

Tc/CD8+

T cells are cytotoxic, need to be activated by helpers to attack. Active cells are CTLs. They attack target cells by releasing perforin and granzymes. Granzymes induce apoptosis on target cells.

Th/CD4+

T cells mediate communication, activate B cells to produce antibody, activate cytotoxic cells

Macrophages

act as APCs. Present T cells

Memory Populations

after stimulation, B cells and T cells produce memory cell populations

IgE

allergic response Location: Bound to mast & basophil cells throughout body, blood Function: Allergic reactions

Haptens

antigens w/molecular weights, not antigenic by themselves. They must be attached to a larger antigen

Natural Killer cells

attack parasites, tumor cells and virally infected cells. Do not need to be stimulated by antigen. They attack cells which do not express MHCI antigens

Cytokines

chemical mediators of up and down regulation of the immune system

Lymph Nodes

contain fixed macrophages which clear infection site of immune reactions

Spleen

contains lymphocytes/macrophages; immune response

interleukins

cytokines that serve as communicators between leukocytes

Chemokines

cytokines which induce migrations of leukocytes into areas of infection

Major Histocompatibility Antigens I

expressed on all nucleated cells of the body

Antigen

foreign substance which evokes an immune response. Have molecular weights higher than 10,000

IgD

function largely unknown Location: B cell surface, blood, lymph Function: Not known

IgA

membrane bound antibody, is a dimer Located: Secretions (tears, saliva) blood, lymph Function: Localized protection on mucosal surfaces

Major Histocompatibility Antigens II

only expressed on antigen presenting cells (macrophages, B cells)

IgM

pentamer, first antibody produced in response to exposure, 3-5 days Location: Blood, Lymph, B cell surface Function: Especially effective against microorganisms

B cells

produce antibody, act as antigen presenting cells (APCs)

Thymus

site of maturation for T lymphocytes

Bone marrow

site of production of lymphocytes; B cells mature here

IgG

very specific response to antigens, produced after IgM Located: blood, lymph, intestine Function: Enhances Phagocytosis, neutralizes toxins & viruses Protects fetus

Lymphatics

vessels containing lymph (fluid)