Immunity

lymphoctyes of immune system

1. B lymphocytes 2. T lymphocytes

Method of action of antibodies

1. Bind to extracellular targets such as bacteria, toxins, or free viruses 2. can't directly destroy antigens; but for an antigen-antibody complex

antigens

1. a substance capable of triggering immune response 2. usually large complex molecules 3. can be bacterium, virus, parasite, or portions of these or even cells from another organism 4. MHC proteins (Major Histocompatibility Complex proteins) are a specific group of proteins on the cell's surface which mark the cell as 'self.' 5. MHC proteins have groove that holds either a self antigen or a foreign antigen

Active Humoral Immunity

1. active immunity is when body's B cells come in contact with antigens and produce antibodies. 2. this may be: a. natural: when one suffers a bacterial or viral infection and body produces antibodies b. artificial: vaccine which contains dead or attenuated pathogens is injected and body produces antibodies in response to vaccine.

disorders of immune system

1. allergies 2. autoimmune disorders 3. AIDS

Humoral Response

1. antigen binds to receptor of B lymphocyte specific to the antigen (primary response) 2. B cells multiply and form slumberous cells with same receptors (clones) 3. most cells transform into plasma cells (short life, takes 5 days to create) and others become long lived memory cells 4. plasma cells secrete antibodies, binds with extracellular target containing the antigen that parent B cell was attracted to; plasma cell dies; binding takes place in extracellular environment 5. memory cells live long, when they come in contact with antigen they mount an immediate humoral response (secondary response) 6. initial response typically takes 3 to 6 days after antigen encounter 7. second or later exposure to antigen produces a faster more prolonged and effective response; lymphoctyes has been primed against the antigen, takes hours instead of days.

4. antimicrobial proteins

1. attack pathogens directly to prevent reproduction 2. interferon interferes with virus replication 3. complement is a group of plasma proteins present in an inactive state in blood; is activated by antigen antibody complexes or directly by some microorganisms; when activated it causes lysis of the cells, promotes phagocytosis and promotes inflammation

Organ transplants

1. autograft 2. isograft 3. allograft 4. xenograft

1. phagocytes

1. chief phagocytes are macrophages and neutrophils 2. ingest the organism and it digested by lysosomes 3. macrophages further stimulated by chemicals released by lysosomes, produces additional enzymes that kills cells

Specific Immunity

1. has to be primed hence takes a while to respond. 2. is antigen specific (antigens are substances that provoke an immune response) 3. systemic 4. has memory 5. humoral or provided by antibodies present in body 6. cell mediated

Types of T Cells in Cell Mediated Response

1. helper T cells (CD4), activate other T and B cells. Absence=immunodeficient state 2. regulatory (suppressed) T cells, turn off immune system 3. cytotoxic T cells (CD8), rid body of cancer cells and cells infected by viruses, take part in rejection of grafts and organs

antigen-antibody complex

1. inactivate antigen bearing cells temporarily by precipitation, agglutination, or neutralization 2. this is followed by activation of complement (plasma protein) and phagocytes. 3. leads to cell lysis, phagocytosis, or inflammation response

Cell Mediated Response

1. is mediated by T lymphocytes 2. various types of T cells are present 3. T cells don't recognize free antigens, but respond to antigens on the surface of body cells, like cells infected by viruses, bacteria, parasites; abnormal cells or foreign tissues. Their response is cell-cell reaction. 4. MHC proteins in a cell bind to self antigens or non-self antigens and display them on cell surface. 5. when self antigens are bound the T lymphoctyes recognize them and leave them alone. 6. when non-self antigens are bound the T lymphocytes get activated and bind to the antigens forming memory and helper T cells 7. cytokines and interleukins are substances released by activated helper T Cells and Macrophages, cause positive feedback reaction which causes more T cell formation; some cytokines are toxins and others enhance phagocytic powers of macrophages, others help inflammatory process 8. helper T cells stimulate proliferation of T and B cells, bound to antigen, without there is no response as in AIDS 9. cytotoxic T cells are only T cells that can attack and kill target cells, attack the membrane and cause lysis.

Cells of the Immune System

1. lymphoctyes 2. antigen presenting cell

Passive Humoral Immunity

1. passive immunity is when antibodies are given directly to the individual for protection. This is not long lasting. 2. this may be: a. natural: as when antibodies pass from mother to fetus via placenta or milk b. artificial: when gammaglobulins are injected directly as in cases with rabies, anti venom, etc.

2. natural killer cells

1. present in blood and lymph, are large lymphocytes that attack virus infected cells and cancer 2. release perforins which target the cell membrane or stimulate the cell to program apoptosis (cell death)

antibodies

1. proteins called gammaglobulins, present in plasma 2. also called immunoglobulins 3. five main classes: IgM, IgA, IgD, IgG, IgE

Non Specific (Innate) Immunity: First Line of Defense

1. surface barrier against pathogens, disease causing microorganisms and is provided by skin and mucous membranes

3. inflammation

1. tissue response to injury; symptoms are redness, pain, and swelling 2. injured cells, phagocytes, mast cells, & lymphocytes release chemicals such as histamine, kirins, and prostaglandins 3. cause blood vessel dilation, heat and redness 4. increases capillary permeability, causes fluid to leak to tissue and compress local nerves; swelling and pain; swelling keeps infection isolated 5. area invaded by more mast cells, neutrophils, and macrophages due to chemotactic influence; foreign material is removed and allows healing to begin

T lymphocytes

3 types to know: helper T lymphoctyes, suppressor T lymphocytes, Cytotoxic lymphoctyes Overview: T cells develop from liver or bone marrow stem cells that mature in the thymus. These cells are responsible for cell mediated immunity. T cells contain proteins called T-cell receptors that populate the cell membrane . These receptors are capable of recognizing various types of antigens. There are three major classes of T cells that play specific roles in the destruction of antigens. They are cytotoxic T cells, helper T cells, and regulatory T cells.

Cytotoxic lymphocytes

A T cell that is antigen-specific and is able to search out and kill specific types of virus-infected cells. When cytotoxic T-lymphocytes (CTLs) find cells carrying the viral peptide they are looking for, they induce these cells to secrete proteins that attract nearby macrophages (a type of white blood cells). These macrophages then surround and destroy the infected cells. CTLs are important in the body's response to viruses and cancer.

histamine

A chemical released by the body during an inflammatory response that causes the blood vessels to dilate

prostaglandins

A group of bioactive, hormone-like chemicals derived from fatty acids that have a wide variety of biological effects including roles in inflammation, platelet aggregation, vascular smooth muscle dilation and constriction, cell growth, protection of from acid in the stomach, and many more.

Complement

A series of 20 plasma proteins activated by foreign cells or antibodies to those cells. They lyse bacteria, promote phagocytosis, and promote inflammation

self antigens

A term used to describe all the normal constituents of the body to which the immune system would respond were it not for the mechanisms of tolerance that destroy or inactivate self-reactive B and T cells.

immunoglobulins

Antibodies such as IgA, IgE, IgC, IgM, and IgD that are secreted by plasma cells in humoral immunity.

dendritic cells

Antigen-presenting cells, located mainly in lymphatic tissues and skin, that is particularly efficient in presenting antigens to naive helper T cells, thereby initiating a primary immune response.

antigens overview

Any substance such as a virus, bacterium, or toxin that the body regards as foreign.

xenograft

Different species graft

macrophages

Found within the lymph nodes, they are phagocytes that destroy bacteria, cancer cells, and other foreign matter in the lymphatic stream.

autograft

Graft from your own tissue

allograft

Graft that comes from another human being

kirins

Group of peptides released during an inflammatory response that acts as vasodilators, inducing smooth-muscle contraction and increased vascular permeability.

Helper T lymphocytes

Helper T cells precipitate the production of antibodies by B cells and also produce substances that activate other T cells.

humoral

Immune response in which B cells transform into plasma cells and secrete antibodies

memory cells

Long-lived, few in number, do not act right away but rather circulate through the body and respond quickly to eliminate subsequent invasion by the same antigen

2. Mucous membranes

Mucous membranes act as physical barrier; produce protective secretions which may be acidic, contains lysosomes which are bactericidal and produce antimicrobial proteins called defensins; trap organisms with cilia

Suppressor T lymphocytes

Regulatory T cells (also called suppressor T cells) suppress the response of B cells and other T cells to antigens.

isograft

Tissue graft from identical twin

MHC proteins

What mobilizes the adaptive defenses and provokes an immune response

allergies

allergens like pollen stimulate the B cells which produce antibodies IgE. These attach to mast cells which release histamine and other chemicals, causing sneezing, wheezing, and other symptoms of allergies.

gammaglobulins

antibodies that bind to foreign antigens marking them for disposal

non-self antigens

antigens that generate an immune response because they do not belong in the body.

chemotactic

cause movement of cells towards the inflammation, specifically neutrophils and eosinophils

Antigen presenting cell (APC)

engulf foreign substances and present them on their cell surface for T lymphocytes to react with; macrophages, dendritic cells, and activated B lymphocytes are examples of APCs. They do not respond to specific antigens like B and T lymphocytes.

cell mediated

immunity against abnormal cells and pathogens inside living cells

Immunity

is the ability of the body to defend itself against disease or foreign invasion by organisms like bacteria, viruses, fungi, and parasites. Immune system responds in two ways: non specific/innate or specific/ adaptive immunity

Non Specific (Innate) Immunity: Second Line of Defense

is the internal mechanism which uses cells and chemicals; 5 lines of defense

interferon

prevents production of viruses

AIDS

produced by HIV, which destroys helper T cells thus depressing the immune system.

autoimmune disorders

recognition apparatus breaks down and the body antibodies or attacks it's own cells like in rheumatoid arthritis, myasthenia gravis, multiple sclerosis

5. fever

response to body pyrogens, secreted by leucocytes in response to pathogens; speeds up repair process by increasing metabolism and also makes unavailable substances like iron and zinc requried by bacteria to propagate.

1. Skin

skin's keratin acts as a physical barrier

B lymphocytes

when stimulated, they become plasma cells which secrete antibodies; B cells develop from bone marrow stem cells in adults. When B cells become activated due to the presence of a particular antigen, they create antibodies that are specific to that specific antigen. Antibodies are specialized proteins that travel thorough the bloodstream and are found in bodily fluids. Antibodies are critical to humoral immunity as this type of immunity relies on the circulation of antibodies in bodily fluids and blood serum to identify and counteract antigens.