Approach to Hypersensitivity/Autoimmune Topics Flashcards
Type I Hypersensitivity Steps
Ag exposure
IgE cross link on mast cells
Histamine, leukotrienes, prostaglandins, tryptase released
symptoms of urticaria, rhinitis, wheezing, diarrhea, vomit, hypotension & anaphylaxis (w/ in min of exposure)
When does the reaction occur in type 1 hypersenstivity?
immediate, w/ in min of expsoure
symptoms can return 4-8 hrs after exposure
What are some examples of type 1 hypersensitivities?
pollen allergies, dust mite allergy, bee sting
What helps to treat type 1 rxns?
anti-histamines
What is type 2 cytotoxic hypersensitivity?
IgM or IgG antibody destroys cells by:
opsonization
complement-mediated lysis
AB depend cell cytotoxicity
What are examples of type 2 hypersensitivity?
ABO mismatch, Grave’s disease, myasthenia gravis
What is the pathology of myesthenia gravis?
antibodies to ACH receptor which prevents Ach from binding (type 2)
IgM or IgG causing destruction
Steps for Type 3 Hypersensitivity
Ag-Ab complex formation
Complexes activate complement & neutrophil infiltration of tissue
Tissue inflammation
What are symptoms of tissue inflammation in type 3?
fever, urticaria, lymph node swelling, arthritis, glomerulonephritis, vasculitis
What are the steps of Type 4 hypersensitivity?
Ag exposure activates T cells
T cell activation leads to tissue inflammation
When do symptoms start in Type 4?
48-96 hours after exposure to antigen
What are examples of type 4?
poison ivy rash, PPD testing for TB
delayed reaction
What is an autoimmune condition?
characterized by an immune response against something that is normally found in the body
What is rheumatoid arthritis?
systemic inflammatory disease affecting synovial membranes
granulation tissues develops in joint spaces & erodes into articular cartilage/bone
females>males
How does RA present?
joint swelling, warmth, erythema, decreased ROM
morning stiffness > 1 hr
PIP, MCP, wrist, knees & ankles affected
How do you differentiate RA from OA?
symptoms of RA: affects metacarp joints, no Herbeden’s nodes, joints are soft & warm, stiffness worse after resting
symptoms of OA: distal joints affected, present w/ Herbeden’s nodes, joints are hard & bony, stiffness worse w/ effort
What is common in RA?
MCP joint swelling w/ boutonniere deformities bilaterally
erosions of joints on X rays
What are complications assoc w/ RA?
increased risk of infection from immunosuppression
2x increase in incidence/mortality from leukemia or lymphoma
increased risk of CVD
What is juvenile idiopathic arthritis?
collagen vascular disorder w/ persistent inflammation in 1 or more joints for 6 or more week sin pts<16 yo
How does pauciarticular JIA present?
affects large joints, asymmetric
inflammation involves ciliary body
uveitis (eye inflammation)
How does polyarticular JIA present?
large & small joints, symmetric
How does systemic JIA present?
recurrent high fevers
myalgias, pericarditis, lymphadenopathy
anemia, leukocytosis
What is a complication of systemic JIA?
50% pts develop destructive arthritis (complete resolution is rare)
What is SLE?
inflammatory disorder that females>males
recurrent exacerbations & remissions secondary to auto-AB formation & immune complex deposition (type 3)
What is the genetic component of SLE?
HLA DR2 & DR3
How does SLE present & what is needed for diagnosis?
Pleuritis Oral ulcers Arthritis Photosensitivity Hemolytic anemia Proteinuria/urinary cell casts Positive ANA Postivie anti-dsDNA Lupus cerebritis/seizures Malar rash Discoid rash
need at least 4 of manifestations
How do you distinguish between RA & SLE?
in SLE, erosions in joints are rare & morning stiffness only lasts few min & deforming arthritis is uncommon
in RA, ESR & CRP are SIGNIFICANTLY elevated
What usually causes mortality in SLE pts?
end organ damage
opportunistic infections secondary to immunosuppression
What is psoriasis?
chronic, hyper-proliferative inflammatory disorder characterized by thick adherent scales
How does psoriasis present?
mild pruritus salmon pink plaques w/ adherent silver-white scale extensor surface involvement nail pitting *genetic component
How do you diagnose psoriasis?
history & PE (Auspitz sign w/ pinpoint bleeding after removal of scale)
What are complications assoc w/ psoriasis?
CVD malignancy diabetes HTN metabolic syndrome IBD serious infections other autoimmune disorders
What is MS?
demyelinating disorders of CNS, females>males & develops from 20-40yo
How does MS present?
vision changes (1st sign) vertigo weakness numbness/tingling/pain urinary incontinence/retention Lhermitte's sign
What is Lhermitte’s sign?
electrical sensation running down spine & LE w/ neck flexion
+ for MS
How is MS diagnosed?
MRI
CSF (spinal tap)
What are examples of primary immunodeficiencies?
T cell specific
B cell specific
T/B cell combined
Phagocytic disorders
What are clinical signs that suggest primary immunodeficiency disease?
+ family history
infections in many anatomical locations
increasing frequency & severity of infections w/ age
recurrent serious infections w/ common pathogens
serious infections w/ unusual pathogens
T cell primary immunodef
disseminated intracellular disease that presents in 3-4 months of life
DiGeorge syndrome
B cell primary immunodef
present @ 6 months of age when maternal antibodies disappear, show sinopulmonary & GI infections
CVID
T/B cell combined primary immunodef
combo of T cell & B cell features
SCID
DiGeorge Syndrome presentation
22q11 deletion
thymic aplasia (absent thymic shadow on Xray)
hypoparathyroidism & hypocalcemia (tetany & seizures)
CVID presentation
defect in B cell maturation
present w/ lymphadenopathy & splenomegaly
SCID presentation
onset @ 3 months of age w/ diarrhea, pneumonia, otitis, sepsis
failure to thrive
Phagocytic primary immunodef
sinopulmonary & soft tissue infections
Chediak Higashi syndrome
Chediak Higashi syndrome
defect in microtubular function that leads to decreased phagocytosis
partial oculocutaneous albinism, progressive neuropathy
HIV/AIDS pathogenesis & presentation
spreads thru transmission of body fluids
initially asymptomatic & then have flu-like symptoms:
myalgias fever anorexia headache/fatigue pharyngitis
How is HIV/AIDS diagnosed?
ELISA screen
Western blot confirmation
HIV RNA viral load
What is important to ask about in new patient appointment?
ask about past HIV screen b/c all pts btwn ages 13-64 need to be screened for HIV at least once
How is AIDS diagnosed?
CD4 count<200 cells
presence of an AIDS-defining illness
What are AID defining illnesses?
cytomegalovirus
mycobacterium avium-intracellulare
candidal esophagitis
