Chapter 15 - Allergy & Immunology Flashcards
1
Q
What are the presenting signs of anaphylaxis?
A
by definition, symptoms must appear within 30 minutes of exposure
- skin: pruritis, flushing, urticarial, angioedema
- respiratory: dyspnea and wheezing
- GI: n/v/d
- cardiovascular: hypotension ranging form mild to shock
2
Q
Allergic Rhinitis
A
- an IgE-mediated inflammatory response in the nasal mucosa to inhaled antigens
- seasonal is typically in response to tree, grass, or weed pollens; perennial to indoor allergens like dust mites and animal dander
- may present with sneezing, nasal congestion, rhinorrhea, nasal itching, pale nasal mucosa, allergic shiners, dennie’s lines, or allergic salute
- skin testing is the most effective method for diagnosing allergic rhinitis, but total IgE concentration and nasal smear cytology can also be used
- treatment involves avoidance, medications (intranasal steroids, antihistamines, intranasal cromolyn sodium, and decongestants), and immunotherapy
3
Q
What are allergic shiners, Dennie’s lines, and the allergic salute?
A
- allergic shiner: dark circles under the eyes caused by venous congestion in those with allergic rhinitis
- Dennie’s lines: crease under the eyes resulting from chronic edema
- allergic salute: patients use the palm of the hand to elevate the tip of the nose and relieve itching
4
Q
What is nasal smear cytology?
A
- a way of differentiating allergic rhinitis from other conditions
- more than 10% eosinophils suggests allergic rhinitis whereas predominately PMNs suggests an infectious cause
5
Q
What avoidance precautions are recommended for patients with severe rhinitis?
A
- remove pets from the home or keep them outdoors
- use plastic mattress covers, remove carpets, and remove stuffed animals to reduce dust mites
- reduce humidity to inhibit growth of dust mites and mold
- avoid open windows
6
Q
What is the most effective class of drugs for controlling allergic rhinitis?
A
intranasal steroids
7
Q
Name one first-generation antihistamine and three second-generation ones.
A
- diphenhydramine
- cetirizine, fexofenadine, loratadine
8
Q
Eczema (Atopic Dermatitis)
A
- a type I hypersensitivity reaction
- the skin is overly sensitive to many stimuli, producing pruritus, leading to scratching, causing the skin to become dry and undergo lichenification (thickening)
- presentation is usually in early infancy, before age 5, and in those with a family or personal history of atopy
- presents with pruritus; an acute erythematous, weeping, crusting rash, often complicated by secondary bacterial or viral infection with S. aureus or HSV; and a chronic lichenification with pigmentary changes
- typically begins on the face and the migrates to the antecubital fossa, affecting flexor surfaces more commonly than extensors
- managed with avoidance of triggers, low-to-medium-potency steroids, and antihistamines; patients should bath in tepid water, be blotted dry after, and apply skin lubricants
9
Q
Which foods most commonly cause allergic reactions?
A
egg, milk, peanut, soy, wheat, fish
10
Q
How does food allergy present and how is it diagnosed?
A
- presents with oral symptoms of itching and swelling, GI symptoms, respiratory symptoms, atopic dermatitis, and acute urticaria
- anaphylaxis is the most severe manifestation
- diagnosed based on a careful history, skin testing, radioallergosorbent tests (looking for serum IgE antibodies to specific food antigens), and provocative oral food challenge
11
Q
Chronic Urticaria
A
- a rash lasting more than 6 months
- described as circumscribed, raised, migratory areas of edema that are almost always pruritic
- may be idiopathic or associated with malignancy, SLE, RA, IgG antibodies to IgE receptors, and thyroid disease
- best treated with antihistamines and further evaluation for underlying systemic disease
12
Q
Which components of the immune system are considered innate?
A
- phagocytic cells
- NK cells
- TLRs
- mannose-binding protein
- the alternative pathway of complement
13
Q
Serum Sickness
A
- a type III hypersensitivity in which antibodies to foreign proteins are produced
- most cases caused by drugs acting as haptens
- presents with fever, urticaria, arthralgia, proteinuria, and lymphadenopathy 5-10 days after antigen exposure
14
Q
How does serum sickness compare to an arthus reaction?
A
- both are type III hypersensitivities mediated by IgG
- however, an arthus reaction has a more rapid onset because it is mediated by circulating IgG (the individual has already been sensitized)
- an arthus reaction is more localized than serum sickness
15
Q
IgA Deficiency
A
- the most common immune deficiency
- defined as serum IgA concentrations < 7 mg/dL but normal levels of other isotypes
- most often asymptomatic but with increased risk of airway and GI infections, autoimmune and rheumatic disease, and atopic disease
- since IgA cannot be replaced, treatment involves management of infections and other complications
16
Q
Common Variable Immunodeficiency
A
- a B cell or helper T cell defect, which impairs B cell differentiation, resulting in hypogammaglobulinemia
- often acquired in the 20s-30s, it presents with increased risk of autoimmune disease, bronchiectasis, lymphoma, and sinopulmonary infections
- diagnosed on the basis of hypogammaglobulinemia, a decrease in plasma cells, and diminished mitogen-induced T-cell proliferation in vitro
- treated with monthly IVIG, management of infections, and treatment of chronic diarrhea with nutritional support
17
Q
Severe Combined Immunodeficiency Disease
A
- a group of inherited disorders affecting T- and B-cell functioning
- can be X-linked due to an IL-2R gamma chain mutation or autosomal recessive due to an ADA deficiency
- presents with early infection with opportunistic organisms, chronic diarrhea, and failure to thrive
- diagnosed based on severe hypogammaglobulinemia and the absence of a thymic shadow, germinal centers, and T cells
- treated with antibiotics, nutritional intervention, use of irradiated blood products to prevent GvHD, monthly IVIG, P. caring pneumonia prophylaxis with TMP-SMX
- bone marrow transplant can be curative
18
Q
Ataxia Telangiectasia
A
- autosomal recessive ATM gene mutations on chromosome 1, which impair repair of DNA double strand breaks
- presents with a triad of cerebellar defects, spider angiomas, and IgA deficiency leading to sinopulmonary infections
- patients also have a high risk of malignancy and should avoid ionizing radiation
- AFP is elevated in serum; IgA, IgG, and IgE are all reduced; and there is lymphopenia, T-cell anergy, and cerebellar atrophy
- monitor for malignancies, avoid ionizing radiation, and treat infections
19
Q
DiGeorge Syndrome
A
- a 22q11 deletion causing failure of the 3rd and 4th pharyngeal pouches to develop, leaving the thymus and parathyroids absent
- presents with cardiac anomalies, abnormal facies, thymic aplasia, cleft palate, and hypocalcemia
- there is a measurable reduction in T cells, PTH, and calcium as well as an absent thymic shadow
20
Q
Wiskott-Aldrich Syndrome
A
- an X-linked recessive mutation of the WAS gene, which impairs actin reorganization and TCR signaling
- presents with “WATER”: Wiskott Aldrich, Thrombocytopenia with small platelets, Eczema, and Recurrent Intections with encapsulated organisms
- bleeding is a major cause of mortality
- diagnosed based on thrombocytopenia, platelet size, decreased IgM, diminished antibody response to polysaccharide antigens, and anergy despite near-normal numbers of T cells
- treated with bone marrow transplant, IVIG, splenectomy, and prophylactic antibiotics or IVIG
21
Q
X-Linked Agammaglobulinemia
A
- an X-linked mutation of the BTK gene, which prevents maturation of B cells from pre-B cells to mature cells
- characterized by severe hypogammaglobulinemia, few mature B cells, and normal T-cell number and function
- presents with bacterial and enteroviral infections after 6 months of age
- diagnosed based on diminished levels of all immunoglobin isotypes, absent B cells, and present T cels
- treated with monthly IVIG replacement
22
Q
Chronic Granulomatous Disease
A
- X-linked recessive NADPH oxidase deficiency limits oxidative burst in neutrophils
- increased susceptibility to catalase positive organisms
- abnormal dihydrorhodamine test and no reaction to nitro blue tetrazolium dye
- treat with prophylactic TMP-SMX, itraconazole, and interferon-y
- bone marrow transplant is currative
23
Q
Which organisms are encapsulated?
A
Please SHINE my SKiS
- P. aeruginosa
- Streptococcus pneumoniae
- H. influenza type b
- N. meningitidis
- E. coli
- Salmonella spp.
- Klebsiella pneumoniae
- Group B Strep
24
Q
Which organisms are catalase positive?
A
Cats Need PLACESS to Belch their Hairballs
- Cat = catalase positive
- Nocardia
- Pseudomonas cepacia
- Listeria
- Aspergillus
- Candida
- E. Coli
- Staph
- Serratia
- B cepacia
- H pylori
25
Schwachman-Diamond Syndrome
- an autosomal recessive condition
- characterized by decreased neutrophil chemotaxis, cyclic neutropenia, and pancreatic exocrine insufficiency
- often presents with recurrent soft tissue infections, chronic diarrhea, and failure to thrive
26
Chediak-Higashi Syndrome
- autosomal recessive defect in the lysosomal trafficking regulator LYST which results in a microtubule defect that impairs fusion of phagosomes with lysosomes
- increases one's risk for pyogenic infections by Staph and Strep
- presents with pancytopenia because the microtubule defect impairs mitosis and leads to intramedullary death
- giant granules in leukocytes because they can't be distributed and accumulate at the golgi instead
- presents with defective primary hemostasis due to abnormal dense granules in platelets
- albinism because melanocytes can't hand off pigment to keratinocytes
- peripheral neuropathy because axonal and dendritic transport are impaired
27
How does an early complement deficiency differ from a late complement deficiency?
- early component deficiency is associated with autoimmune disease
- late component deficiency is associated with meningococcal and gonoccal infections
28
C1 Esterase Inhibitor Deficiency
- an AD disorder known as hereditary angioedema resulting form loss of the complement regulator
- there is unregulated activation of kallikrein, leading to increased levels of bradykinin, as well as accumulation of anaphylatoxins, which results in swelling
- ACE inhibitors are contraindicated because they can lead to bradykinin accumulation
