Lecture 6: Dermatology Flashcards
What are the components of the immune system
Cells
recognition molecules
soluble factors
Describe nonspecific immunity
First line of defence, non specific
Describe the anatomic and physiologic portion of nonspecific immunity
skin, mucosa, cilia
stomach pH, Body Temperature
Describe the cellular portion of the nonspecific immunity
phagocytic cells, NK cells
describe the molecular portion of the nonspecific immunity
inflammation
complement system
Where do the cells from the nonspecific immunity come from
recruited by the molecules of inflammation
What is the function of the cells of the nonspecific immunity
ingest + destroy pathogens
neutralize toxins
Describe the self/nonself identification by neutrophils, monocytes, tissue macrophages, NK cells
Express membrane receptors that innately recognize several pathogens (pathogen recognition receptors) Recognizes PAMPs (pathogen-associated molecular patterns) Also DAMPS (damage associated molecular patterns)
Describe the cell mediated specific immunity
T-Lymphocytes for intracellular pathogens
B-Lymphocytes for extracellular pathogens and toxins
Describe the characteristics of specific immunity
Specificity Diversity Memory Self/non-self recognition MHC molecules
Describe T Lymphocytes
Contains T Cell Receptor
TCR can only recognize antigen in combination with a MHC molecule.
Each T Lymphocyte expresses a different TCR
What is the CD4 T Lymphocyte
Helper T lymphocytes Recognizes MHC class II: found on antigen presenting cells
What is the CD8 T Lymphocyte
Cytotoxic T Lymphocytes: Recognizes MHC class I: found on all nucleated cells
What is a signal 2 lymphocyte:
important for tolerance and auto-immunity
What do T-Lymphocytes do when activated
Expand clonal
differentiate into: Effector Cells or Memory cells
Describe the antigen receptor in B Lymphocytes
Membrane-bound immunoglobulin. The immunoglobulin gene can rearrange- antigen recognition diversity.
What happens to B Lymphocytes when activated
Expand clonally Differentiates into: Effector cells plasma cell (antibody secreting) Needs the action of T-helper lymphocyte Memory cells
What is the function of a macrophage
Phagocytosis
Antigen presentation to T-Lymphocyte
MHC class II
What is the function of a dendritic cell
Very efficient antigen presenting cell
Capture antigens in circulation and present to T-Lymphocytes in lymph nodes
Describe a Type 1 hypersensitivity
Immediate hypersensitivity
Misdirected/innapropriate response
occurs within minutes of exposure
Describe the type 1’s immediate hypersensitivity
IgE mediated
Against:
Environmental antigens (allergens)
Parasite antigen
What does a type 1 hypersensitivity reaction require
Need to be previously SENSITIZED
Mediated by mast cells
What does mast-cell degranulation in a type 1 hypersensitivity reaction result in
Vasodilation Edema Smooth muscle contraction Mucus production Inflammation
Describe the systemic reaction in a type 1 hypersensitivity
Anaphylaxis
Describe the localized type 1 hypersensitivity reaction
Skin, mucosa, GIT
Atopy, allergic rhinitis
What is allergic dermatitis
cutaneous manifestation of type I hypersensitivity
Inhalation, ingestion, percutaneous
What do you call an allergic dermatitis with a genetic predisposition
atopic dermatitis
Describe a flea bite hypersensitivity
Most common hypersensitivity in cats & dogs
Very pruritic dermatitis (mostly on back)
What is urticaria and angiodema
Most often in horses and dogs
Multifocal or localized areas of edema
Urticaria: superficial
Edema: deep dermis and subcutis
What are the immunologic causes of Urticaria and Angioedema
food, drug, antisera, insect bites
what are the non immunologic causes of urticaria and angiodema
heat, exercise, stress
Describe a cytotoxic hypersensitivity
Development of antibodies against self cells or tissue
May be from self antigen or exogenous antigen adsorbed to self
What does a cytotoxic hypersensitivity cause
IMHA, ITP (cytotoxic) Myasthenia gravis (altered function)
What immune complexes are involved in a type 2 hypersensitivity
IgM and IgG
What does a type 2 hypersensitivity reaction require
a sensitized host
What enhanced phagocytosis of antigen by macrophages in type 2 hypersensitivity
opsonization by antibodies or complements
How can an antibody activate the complement system and what happens when it does it
Antibody can activate the complement system, via the classical pathway, resulting in the elaboration of inflammatory mediators
What can antibodies against cell receptors do
activate or inhibit cell function. ex: TSH
What is immune mediated hemolytic anemia
Common, life-threatening acute anemia
Young middle-aged females, cocker spaniels
Usually idiopathic
Infection, drugs, neoplasia
What is neonatal isoerythrolysis
A form of IMHA Colostrum derived maternal antibodies Attacks newborn’s RBC Common in horses Immunosensitization of mother to incompatible blood type from stallion
8-10h after birth up to 4-5 days
what is pemphigus (foliaceous)
Most common and milder form of pemphigus
Often adverse reaction to drugs
Autoantibodies against a protein in desmosomes
Pustules with acantholytic keratinocytes
What are three different type 2 hypersensitives
Immune Mediated Hemolytic Anemia
Neonatal isoerythrolysis
Pemphigus
Describe a type 3 hypersensitivity
Immune-complex hypersensitivity
Antigen-antibody complexes that activate complement and cause damage
Similar to type II
Type II: antigen directed against self
Type III: antigen just get “stuck” to tissue
What happens when immune complexes are deposited into tissues
Activation of complement system
tissue DAmage
Why do antibody antigen complexes go wrong
Improper atb/ag ratio
Weak, chronic atb response
Too many atb-ag complexes
What is type 3 hypersensitivity caused by
chronic/persistant infection
foreign antigen inhalation
Where do antibody-antigen complexes accumulate in
Blood vessels
Synovial membranes
Glomeruli
Choroid plexus (brain)
What is systemic lupus erythematous
Multiorgan disease (dogs; rarely cat & horse) Defective T-Lymphocyte suppression results in B-Lymphocyte hyperactivity
What are the predisposing factors for systemic lupus erythematous
Genetics
Viral infection
Hormones
UV light
Describe how systemic lupus erythematous affects the body
Formation of autoantibodies to a variety of antigens, including nucleic acid
Organ specific antigens
Clotting factors
Cells (RBC, platelets, leukocytes)
Main damage: atb-ag complexes
Many tissue, notably skin (intensified by UV light)
What are the skin symptoms of systemic lupus erythematous
Local or generalized
Erythema, depigmentation, alopecia, crusting
What are the systemic signs of systemic lupus erythematous
Polyarthritis
Fever
Anemia, thrombocytopenia
Proteinuria
What causes equine infectious anemia
caused by the lentivirus
how does the lentivirus cause equine infectious anemia
infects monocytes and macrophages
what does equine infectious anemia do to the body
Immune-mediated (atb-atg complexes deposition)
Decreased erythropoiesis
how do you diagnose equine infectious anemia
coggins test for diagnostic
describe a type 4 hypersensitivity
Delayed-type hypersensitivity
Cell mediated hypersensitivity
Interaction between T-lymphocytes and specific antigens
Sensitized T-lymphocytes
Response is 24-48h after exposure
Granuloma formation
Unlike type I, II & III:
NOT dependent on antibody
describe tuberculosis
Caused by acid-fast bacilli of the genus Mycobacterium.
Chronic, debilitating disease
Occasional acute, rapidly progressive course.
Affects practically all species of vertebrates
Mycobacterium Tuberculosis and others
Often the body is unable to clear the infection
Chronic Granuloma formation
Describe johne’s disease
Mycobacterium paratuberculosis.
Chronic, contagious granulomatous enteritis
Often in cattle
Persistent diarrhea, progressive weight loss, debilitation, and eventually death
Thickened and corrugated intestine with enlarged and edematous neighboring lymph nodes
Granulomas
What is auto-immune thyroiditis
Chronic and progressive lymphocytic infiltration and subsequent destruction of the thyroid gland
Who is predisposed to getting auto-immune thyroiditis
Doberman Pinschers, Beagles, Golden Retrievers, and Akitas
What is special about auto-immune thyroiditis
Probably has both humoral (Type II - cytotoxic) and cell-mediated (Type IV - delayed) components
MHC probably involved
What is bovine/canine leukocyte adhesion deficiency
Genetic, congenital anomaly of leukocytes
Prevents leucocytes from migrating from the blood in the tissues
Very high neutrophilia
Animals are highly susceptible to infection
Die very young
Describe feline infectious peritonitis
Mutation of benign enteric coronavirus to FIP virus
Infects monocytes & macrophages and spreads through blood
Type III (immune complex)
Vasculitis
Type IV (delayed) also likely
Granulomas
Describe keratitis sicca
Due to an aqueous tear deficiency
Usually results in persistent, mucopurulent conjunctivitis and corneal ulceration and scarring
Dogs, cats & horses
Dogs: often autoimmune dacryoadenitis of both the lacrimal and nictitans glands
Not well understood
