chapter 37

3 ways that antibodies react with antigens

(1) by coating the antigens' surfaces if they are particular substances, (2) by neutralizing the antigens if they are toxins, and (3) by precipitating the antigens out of solution if they are dissolved.

antibody

A protein that acts against a specific antigen

Most common form of respiratory allergy:

Allergic rhinitis (hay fever, seasonal allergic rhinitis) is the most common form of respiratory allergy, which is presumed to be mediated by an immediate (type I hypersensitivity) immunologic reaction.

Dermatitis Medicamentosa (Drug Reactions)

Dermatitis medicamentosa, a type I hypersensitivity disorder, is the term applied to skin rashes associated with certain medications. Leading cause of fatal anaphylaxis,

example of antihistamine

Diphenhydramine (Benadryl) is an example of an antihistamine, a medication that displays an affinity for H1 receptors. Cimetidine (Tagamet) and ranitidine (Zantac) target H2 receptors to inhibit gastric secretions in peptic ulcer disease.

Provocative testing

Direct administration of the suspected allergen to the sensitive area such as the conjunctiva, nasal, bronchial mucosa, or GI tract.

Normal serum IgE levels

Normally, serum IgE levels are below 1.0 mg/mL

two types of chemical mediators:

Primary mediators are preformed and are found in mast cells or basophils. Secondary mediators are inactive precursors that are formed or released in response to primary mediators.

leukotrienes

Secondary chemical mediator that starts the inflammatory response. Compared with histamine, leukotrienes are 100 to 1000 times more potent in causing bronchospasm.

Guidelines for the interpretation of skin test:

Skin tests are used most frequently with the diagnosis of allergic rhinitis Negative test results are helpful in ruling out food allergy. Positive skin tests correlate highly with food allergy

Cytotoxic (Type II) Hypersensitivity

The body mistakenly identifies a normal constituent of the body as foreign and initiates an attack which may lead to cell or tissue death. This reaction involves the binding of either IgM or IgG antibody to a cell bound antigen.

serum-specific IgE test,

The serum-specific IgE test, formerly known as RAST, is an automated test performed on blood samples by a pathology laboratory. As the name suggests, it detects free antigen-specific IgE in serum as opposed to antigen-specific IgE bound to mast cells in the skin.

Histamine

This is a primary chemical mediator. It is also the first chemical mediator to be released in a immune response. substance in the body that causes increased gastric secretion, dilation of capillaries, and constriction of the bronchial smooth muscle

Triamcinolone

Triamcinolone is an inhaled corticosteroid administered by a metered-spray device. It may cause drying of the nasal mucosa and burning and itching sensations

immunoglobulins

a family of closely related proteins capable of acting as antibodies

contact dermatitis

a type IV delayed hypersensitivity reaction, is an acute or chronic skin condition caused by contact with an exogenous substance that elicits an allergic response. There are four basic types: allergic, irritant, phototoxic, and photo allergic

Mast cells:

are located in the skin and mucous membranes, play a major role in IgE-mediated immediate hypersensitivity. When mast cells are stimulated by antigens, powerful chemical mediators are released, causing a sequence of physiologic events that result in symptoms of immediate hypersensitivity

examples of atopic diseases

asthma, allergic rhinitis, and atopic dermatitis

Hymenoptera

bees, ants, wasps

Diagnostic test for a patient with allergic disorders include:

blood tests, smears of body secretions, skin tests, and the serum-specific IgE test (formerly known as radioallergosorbent test [RAST]). These test are ONLY for SUPPOERTIVE DATA.

Antigens are divided into 2 groups:

complete protein antigens and low-molecular-weight substances.

angioneurotic edema

condition characterized by urticaria and diffuse swelling of the deeper layers of the skin

signs and symptoms of histamine exposure:

erythema; localized edema in the form of wheals; pruritus; contraction of bronchial smooth muscle, resulting in wheezing and bronchospasm; dilation of small venules and constriction of larger vessels; and increased secretion of gastric and mucosal cells, resulting in diarrhea

uriticaria

hives

Types of Immunoglobulins

immunoglobulin E (IgE) is involved with an allergic reaction. IgA combines with antigens and activates complement. IgB coats the surface of B lymphocytes. IgG is the principal immunoglobulin formed in response to most infectious agents.

hapten

incomplete antigen

Examples of Type 2 hypersensitivity reactions

myasthenia gravis, the body mistakenly generates antibodies against normal nerve ending receptors. In Goodpasture syndrome, it generates antibodies against lung and renal tissue, producing lung damage and kidney injury. pernicious anemia, hemolytic disease of the newborn, transfusion reaction, and thrombocytopenia

Where are IgE producing cells located?

resp & intestinal mucosa

Serotonin

secondary chemical mediator that acts as a potent vasoconstrictor and bronchodilator

T lymphocytes (T cells) function

secrete substances that direct the flow of cell activity, destroy target cells, and stimulate the macrophages. T cells assist B cells

Because allergic rhinitis is induced by airborne pollens or molds, it is characterized by the following seasonal occurrences

Early spring—tree pollen (oak, elm, poplar) Early summer—grass pollen (Timothy, Redtop) Early fall—weed pollen (ragweed)

where is H1 and H2 receptors found?

H1 receptors are found predominantly on bronchiolar and vascular smooth muscle cells; H2 receptors are found on gastric parietal cells.

When does histamine peak ?

Histamine's effects peak 5 to 10 minutes after antigen contact. erythema; localized edema in the form of wheals; pruritus; contraction of bronchial smooth muscle, resulting in wheezing and bronchospasm; dilation of small venules and constriction of larger vessels; and increased secretion of gastric and mucosal cells, resulting in diarrhea

Hypersensitivity

Hypersensitivity is an excessive or aberrant immune response to any type of stimulus. It usually does not occur with the first exposure to an allergen.

atopy

IGE mediated disease such as allergic rhinitis, that have a genetic component.

Anaphylactic (Type I) Hypersensitivity

Most severe type of hypersensitivity Reactions occur almost immediately upon exposure to antigen anaphylaxis is characterized by edema in many tissues, including the larynx, and is often accompanied by hypotension, bronchospasm, and cardiovascular collapse in severe cases. Primary chemical mediators are responsible for the symptoms of type I hypersensitivity because of their effects on the skin, lungs, and gastrointestinal tract. If chemical mediators continue to be released, a delayed reaction may occur and may last for up to 24 hours. Can be local or systemic reactions

Bradykinin

Secondary chemical mediator that has the ability to cause increased vascular permeability, vasodilation, hypotension, and contraction of many types of smooth muscle, such as the bronchi. Increased permeability of the capillaries results in edema. that stimulates nerve fibers and causes pain

True or false Corticosteroids and antihistamines, including over-the-counter allergy medications, suppress skin test reactivity and should be stopped 48 to 96 hours before testing, depending on the duration of their activity. False-positive results may occur because of improper preparation or administration of allergen solutions.

True

IgE immunoglobulins are involved in

allergic reactions and parasitic infections.

Decongestants can cause a ? in blood pressure

an increase

Adrenergic agents:

are vasoconstrictors of mucosal vessels, are used topically in nasal (Afrin) and ophthalmic (Alphagan P) formulations in addition to the oral route (pseudoephedrine [Sudafed]). They activate the alpha-adrenergic receptor sites on the smooth muscle of the nasal mucosal blood vessels, reducing local blood flow, fluid exudation, and mucosal edema.

Where are immunoglobulins found?

immunoglobulins can be found in the lymph nodes, tonsils, appendix, and Peyer patches of the intestinal tract or circulating in the blood and lymph.

what are the side effects of oral corticosteroid therapy

include adrenal suppression, fluid retention, weight gain, glucose intolerance, hypertension, and gastric irritation.

Type 3 hypersensitivity immune complex

involves immune complexes that are formed when antigens bind to antibodies. Inflammation occurs due to the deposits of the complexes into tissues or vascular endothelium. which then leads to increase in permeability.

Delayed-Type (Type IV) Hypersensitivity

is a CELL MEDIATED immune reaction in which T-cell-dependent macrophage activation and inflammation cause tissue injury. Occurs 1-3 days after exposure to antigen.

atopic dermatitis

is a type I immediate hypersensitivity disorder characterized by inflammation and hyper reactivity of the skin.Atopic dermatitis is a chronic pruritis inflammatory skin disease. Nurses should be aware that atopic dermatitis is often linked in a process called the atopic march that often leads to asthma, allergic rhinitis, or food allergy

what are the three methods of immunotherapy

subcutaneous immunotherapy (SIT), sublingual immunotherapy (SLIT), and epicutaneous immunotherapy (EPIT).

complete protein antigens

such as animal dander, pollen, and horse serum, stimulate a complete humoral response.

low-molecular-weight substances

such as medications, function as haptens (incomplete antigens), binding to tissue or serum proteins to produce a carrier complex that initiates an antibody response

positive reactionS of skin tests are evidenced by:

the appearance of an urticarial wheal (round, reddened skin elevation), localized erythema (diffuse redness) in the area of contact, or pseudopodia (irregular projection at the end of a wheal) with associated erythema is considered indicative of sensitivity to the corresponding antigen.

B lymphocytes (B cells) function

when encountered by an antigen, the B cells stimulate plasma production, which is the site of antibody production. This results in the outpour of antibodies to destroy the antigen

Eosinophil range

0% to 3%

WBC count range

4500-11000

mast cells

Connective tissue cells that contain heparin and histamine