- the structure in the antigen that is recognized by the B cell or the T cell.

- a substance recognized by the immune system - serves as the target of the immune response but may not necessarily lead to an immune response.

- any substance capable of inducing an immune response, whether humoral or cell mediated or both.

- the study of the immune system and the immune response.

WHITE BLOOD CELLS - which are 50% - 80% of white blood cells - approximately 20% - 45% of total white blood cells - 3% - 8% of white blood cells

CELLS OF THE IMMUNE SYSTEM - play a major role in acute inflammation as well as in bacterial infections.

CELLS OF THE IMMUNE SYSTEM - mainly involved in chronic inflammation.

CELLS OF THE IMMUNE SYSTEM - are the predominant inflammatory cells in viral infections.

CELLS OF THE IMMUNE SYSTEM - are also predominant in chronic inflammation - cells that belong to the mononuclear phagocyte system play crucial roles as antigen presenting cells

Other white blood cells that are part of the innate arm of the immune system - possess granules that play a role in type 1 hypersensitivity reaction or allergy - also secrete a substance called maior basic orotein tha is toxic to parasites, especially helminths or worms.

Other white blood cells that are part of the innate arm of the immune system - also play a role in allergies - granules of both eosinophils and basophils contain histamine which when released is responsible for the changes seen during the initial phase of an allergic reaction

Other white blood cells that are part of the innate arm of the immune system - are membrane bound cell fragments that are derived from large cells called megakaryocytes. - mainly involved in blood coagulation - they secrete substances that play a role in inflammation.

- cells are classified as large granular lymphocytes and are part of the body's innate immune system.

GMAED • major immunoglobulin in the circulation • predominant in the secondary immune response. • only immunoglobulin that can cross the placenta. • involved in chronic inflammation

GMAED • predominant in acute inflammation and the primary immune response • the largest and more effective fixer of complement. • functions as an antigen receptor on the surface of B cells.

GMAED • also known as the secretory immunoglobulin and acts to prevent adhesion of microbes to mucosal surfaces • provides protection to the gastrointestinal tract, digestive tract, and genitourinary

GMAED • the reaginic antibody • the predominant immunoglobulin in type I hypersensitivity and parasitic infections.

GMAED • functions as a surface marker for B cells and has no biologic activity.

- is the body's defense against extracellular organisms. - Antibodies produced can help neutralize viruses. - These antibodies also serve as the body's defense against encapsulated organisms as well as toxin producing microbes.

- involves both the helper T cells and the cytotoxic T cells.

- involves the action of specific proteins and molecules that act to destroy antigens - includes cytokines and the complement system - involves the action of specific proteins and molecules that act to destroy antigens - includes cytokines and the complement system.

- involves the action of natural killer cells and phagocytic cells.

TYPE _______ HYPERSENSITIVITY - mediated by IgE and is commonly known as allergy. - The effector cells are mast cells and the predominant inflammatory cells are the eosinophils.

TYPE _______ HYPERSENSITIVITY • called antibody mediated hypersensitivity • Triggered by antigen antibody complexes that causes activation of the classical pathway of complement system. • Examples: - transfusion reactions - blood incompatibilities(ABO and Rh incompatibilities) - autoimmune hemolytic anemias - certain drug reactions that will lead to hemolysis of red blood cells

TYPE _______ HYPERSENSITIVITY • is immune complex mediated hypersensitivity • Also triggered by antigen antibody complexes • antibody involved is IgG or IgM • The main difference is the site of formation of immune complexes - resulting deposition of these complexes in tissues and blood vessels leading to fibrinoid necrosis. • It has two forms • acute serum sickness (systemic form) | • Arthus reaction (localized form)| • complication of immunization especially with vaccines that are given with multiple doses (e.g., DPT). • If the vaccine is given before the next schedule is due and is injected at the same site as the previous dose, immune complexes form and precipitate in the walls of blood vessels leading to fibrinoid necrosis - result is the formation of a localized area of tissue necrosis at the injection site

TYPE _______ HYPERSENSITIVITY • delayed type hypersensitivity • can be induced by intracellular pathogens like Mycobacterium tuberculosis as well as certain viruses and fungi, including their skin tests • tuberculin skin test for tuberculosis - the antigen (PPD) is administered into the skin of a previously immunized individual or someone who was exposed to a known case of tuberculosis. - detectable skin reaction (called induration) is seen within 24-48 hours (sometimes up to 72 hours) after administration. • A positive tuberculin test is seen - induration measuring > 10 mm and does not necessarily mean that the tested person has tuberculosis but may mean positive exposure to an active case. • Other examples - contact dermatitis - rheumatoid arthritis

• contains a weakened (also called attenuated) or inactivated form of the organism • may contain the entire organism or a specific portion of the microbe - also known as sub unit • may also be derived from toxins produced by the microorganism - Toxoids • are designed to stimulate the body's immune system to produce the antibodies specific to the organism or its components so that these are recognized as foreign and will be destroyed immediately upon entry of the organism into the body

TYPES OF VACCINES - are prepared using organisms with limited ability to cause disease - useful for protection against infections caused by enveloped viruses - usually long lived and, depending on the route of administration

TYPES OF VACCINES • developed based on the principle that certain diseases are caused by exotoxins produced by the causative agents • tetanus, botulism, pertussis, diphtheria, and cholera • toxoids were produced from the exotoxins. • Toxoid vaccines are advantageous because:

TYPES OF VACCINES - refer to vaccines derived from bacterial sources

TYPES OF VACCINES • derived from viruses • first killed vaccine to be produced was the typhoid vaccine during the latter part of the 19th century. - Examples of inactivated vaccines that are popularly used are the polio vaccine and hepatitis A vaccine • Multiple doses are needed to elicit a strong immune response • local reactions may be seen at the site of injection

TYPES OF VACCINES • produced the same way as the killed/inactivated vaccine • instead of using the entire organism as the antigen to stimulate antibody production, only a specific antigen or structure on the organism is used. • Its effectivity relies on accurate selection of the sub unit to be used • Examples - hepatitis B vaccine where the surface antigen of the virus was used in its development - vaccines against Haemophilus influenzae and Streptococcus pneumoniae where the capsules of both organisms were used.