Immuno Flashcards
A mother brings her 6-year-old son to the pediatrician with a 7 week history of cough and shortness of breath. The mother says that his cough is dry and worse at night when it sometimes wakes him up from sleep. The cough has not been associated with a fever and growth charts reveal that he is growing well. Past history is significant only for travel to many countries on vacation over the last few years. Physical exam reveals end expiratory wheezing and the finding shown in Figure A. The most likely cause of this patient’s symptoms is an example of which of the following types of disorders?
Type I hypersensitivity
Type II cytotoxic hypersensitivity
Type II non-cytotoxic hypersensitivity
Type III hypersensitivity
Type IV hypersensitivity
This patient with cough and shortness of breath who presents with wheezing and eczema most likely has asthma, which is a type I hypersensitivity reaction.
Type I hypersensitivity is caused by antigen cross-linking of IgE on sensitized mast cells. This causes the release of vasoactive mediators (e.g., histamine, leukotrienes, and prostaglandin D2) and inflammatory mediators (e.g., TNF-alpha and leukotriene B4). This mechanism is responsible for asthma, allergic rhinitis (hay fever), anaphylaxis, angioedema, urticaria, and allergies to medications and food. Asthma, in particular, is characterized by cough and shortness of breath that is worse at night and associated with end-expiratory wheezing.
Figure A demonstrates the characteristic appearance of an atopic dermatitis rash. These rashes frequently present as erythematous plaques and papules around the flexor surfaces of the elbows and knees.
Urticaria pathogenesis and presentation
It is almost always a hypersensitivity disorder.
Type 1 hypersensitivity (IgE mediated mast cell degranulation)
presentation of raised red itchy plaques mostly on trunk and extremities
pathogenesis of hereditary angioneurotic edema
cause is genetic by AD transmission → C1 inhibitor deficiency → classical complement pathway has “no breaks” → excess secretion of bradykinin (mediator of edema)
what is the specific immunological mediator of edema
bradykinin
mn: Brady sounds like Brody which sounds like the name of a swol football player
Stevens-Johnson Syndrome and toxic epidermal necrolysis are both variants of which type of skin disorder
Erythema Multiforme (an acute inflammatory dermatosis)
what are the types of immunce cells present in the epidermis versus the dermis
- Epidermis: keratinocytes, Langerhans cells intraepithelial lymphocytes (IELs) provide first line of defense in the outer epidermal layer
- Dermis: T cells, dendritic cells, macrophages, and mast cells
What are the GENERAL descriptions of the 4 types of hypersensitivity responses?
what is the hallmark of type I reaction
degranulation of mast cells
what type of hypersensitivity reaction is shown
Type 1
what type of hypersensitivity reaction is shown
Type II
_________is a marker of mast cell degranulation
tryptase
____and _______antibodies induce hypersensitive reactions
by activating complement.
IgG and IgM antibodies, induce hypersensitive reactions
by activating complement.
what two types of antigens most commonly initiate a Type II hypersensitivity reaction
- self
- drug
Which hypersensitivity reactions present within 1-3 hours of exposure to antigen?
Types II and III
What are the type(s) of immune cells that are responsible for Type III HSRs
Helper T cells and Cytotoxic T cells
- Polyarteritis nodosa
- Poststreptococcal glomerulonephritis
- Serum sickness
- Arthus reaction
- Systemic lupus erythematosis
- Hypersensitivity Pneumonitis (Farmer’s lung)
These are all examples of what type of HSR
Type III
what is the characteristic presentation of an atopic dermatitis rash.
These rashes frequently present as erythematous plaques and papules around the flexor surfaces of the elbows and knees. Excoriations, scaling, and vesicles can sometimes be seen.
Of note, infants often have lesions on the cheeks, scalp, and extensor surfaces while older children and adults have lesions on the flexor surfaces.
In _________ (which HSR) reactions, antigen-antibody complexes deposit in healthy tissues, initiating localized inflammatory responses in these tissues.
Type III
Name an environmental risk factor for lupus
Type I diabetes mellitus, multiple sclerosis, and Hashimoto’s thyroiditis are all examples of which hypersensitivity reactrion
Type IV
