Specific Acquired Immune Response A specific response that is directed only at the invading agent. Two keys words to remember: Specific Memory bio-alive.com

Lymphocytes There are 3 types of lymphocytes (white blood cells): T Cells Thymus-dependent B Cells Bone marrow-derived Natural Killer Cells

Immune System Antibody-mediated (humoral)Immunity Involves the production of antibodies by B cells. Cell-mediated Immunity Involves a variety of cell types including: T cells, macrophages, and natural killer cells.

Antigens and Antibodies Antigens Induce an immune response. Induce the formation of antibodies. Epitopes Individual molecules on the microbe’s surface that the body recognizes as foreign. Antibodies React specifically to the antigen that induced them. More specifically, the epitope that induced them.

Antibodies All antibodies belong to a group of proteins called immunoglobulins. Immunoglobulins are globular glycoproteins in the blood that participate in immune reactions. Also found in lymph, tears, saliva, and colostrum. There are 5 classes of immunoglobulins (Ig): IgA IgD IgE IgG IgM

Basic Structure of Antibodies Looks like a Y. Has 2 light chains. Has 2 heavy chains. Has 2 antigen binding sites (purple) that are variable regions. Has a constant region (bottom of Y).

Acquired Immunity Active Acquired Immunity Natural Artificial Passive Acquired Immunity Natural Artificial

Hypersensitivity Reactions Inappropriate or excessive immune responses to antigens. Depend on the presence of an antigen and T cells that are sensitized to that antigen. May or may not involve antibodies. There are 4 types of hypersensitivity reactions: Immediate-type Hypersensitivity Reactions Types I – Types III Delayed-type Hypersensitivity Reactions Type IV

Type I Hypersensitivity Reactions Also called anaphylactic reactions. Include classic allergic responses like hay fever symptoms, asthma, hives, etc. All involve IgE antibodies and the release of chemical mediators (especially histamine) from mast cells and basophils. How does this happen?

Type I Hypersensitivity Reactions cdavies.wordpress.com

Type I Hypersensitivity Reactions Localized Anaphylaxis Depends on how the allergen enters the body. Involves chemical release of mast cells in area. Involves IgE antibody Systemic Anaphylaxis Involves chemical release of basophils in bloodstream. Involves IgE antibody. Throughout body so usually more serious. Anaphylactic shock – severe, potentially fatal condition.

Type II Hypersensitivity Reactions Cytotoxic reactions Body cells are destroyed during this reaction. Involve IgG or IgM antibodies. Ex. - incompatible blood transfusions

Type III Hypersensitivity Reactions Immune complex reactions. Damage to tissues and organs is initiated by antigen – antibody complexes. Involve IgG or IgM antibodies, complement, and neutrophils. Ex. – serum sickness Ex. – some autoimmune diseases like rheumatoid arthritis.

Type IV Hypersensitivity Reactions Delayed-type Hypersensitivity or cell-mediated immune reactions. Are part of cell-mediated immunity. Occur usually between hours or longer after exposure or contact. Involves a variety of cell types including macrophages, cytotoxic T cells, and NK cells But antibodies do not play major roll. Ex. Contact dermatitis after touching certain metals, poison ivy, creams, etc. Ex. Tuberculosis test uses this science to look for the presence of TB in person or past exposure.

Immunodiagnostic Procedures Many different types of tests that are based on immunologic principles. Usually expose patient’s serum to suspected microbe, toxin, etc. If antibodies present they will bind to some type of protein present in the microbe/toxin etc. This will result in some visible change that suggests presence of a pathogen. No change indicates pathogen not present. Ex. – Enzyme Linked Assay (ELISA)