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Flashcards in IMMUNOLOGY Deck (42):

HLA associated with diseases:




HLA associated with diseases:




  • Psoriasis
  • Ankylosing spondylitis
  • Inflammatory bowel disease
  • Reactive arthritis (Reiter's)



HLA associated with diseases:




HLA associated with diseases:


Rheumatoid arthritis



Follicular Dendritic cells 

  • not from bone marrow
  • No MHC II and not APC
  • only in lymph follicle
  • help mature B cells


Characteristic finding on electron microscopy of a dendritic cell with Langerhans cell histiocytosis

  • Birbeck granules (Tennis rackets), immature dendritic cells from monocyte lineage;
  • do not stimulate T lymphocytes via antigen presentation.
  • Express S-100 and CD1a


Site of negative selection for T-lymphocytes

  • Corticomedullary junction of the thymus
  • T-cells expressing TCR's with high affinity for self undergo apoptosis
  • Cells become either CD4 or CD8 T-cells



  • Induces helper T cell to become Th1 cell
  • Virally infected cells secrete IL-12.
  • More Th1 secrete IL-2 which stimulates cytotoxic T cells to kill virally infected cells
  • IL-2 is the most important cytokine in activating antigen primed helper T cells


How do interferons work?

  • induce production of ribonucleus that degrades viral mRNA (alpha and beta)
  • Increase expression of MHC I and MCH II (gamma interferon) and antigen presentation
  • Activate NK cells to kill virally infected cells


Macrophages of bone?



gene complex RAG 1 and RAG 2 

  • gives rise to a protein that initiates VDJ recombination in B and T cell development
  • Recognize Recombination Signal Sequences that flank VDJ sequences
  • Rearrangement begins at breaks in the dsDNA located at the RSS
  • Mutations in RAG genes lead to inability for VDJ recombination and arrest B and T cell development


When is passive immunity necessary?

To Be Healed Rapidly


  • Tetanus toxoid
  • Botulinum toxin
  • HBV
  • Rabies, (RSV for babies, once a month vaccine)




Screening for SLE?

Antinuclear antibodies (ANA)



Anti-dsDNA, anti-smith

More specific for SLE + Renal disease


Antihistone autoantibody

90% Drug induced lupus


Seen in 50% of patients with SLE


Given the following features, what type of graft rejection is occuring? 

Obliterative vascular damage

(Fibrosis of the graft tissue and blood vessels)

  • Chronic rejection
  • Months-years
  • Class I MHCnon-self perceived by CTLs as class I MHCself presenting non-self antigens
  • Irreversible
  • T-cell and antibody mediated damage


Given the following features, what type of graft rejection is occuring? 

Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate

  • Acute rejection
  • Weeks
  • Cell mediated due to CTLs reacting against foreign MHCs
  • Reversible with immunosuppresants


Given the following features, what type of graft rejection is occuring? 

Macupapular rash, jaundice, diarrhea, hepatosplenomegaly

  • GVHD
  • Timeframe Varies
  • Grafted immunocompetent T cells proliferate in the irradiated immunocompromised host and reject cells with "foreign" proteins resulting in severe organ dysfunction
  • Usually occurs when organs rich in lymphocytes are donated: Bone and liver


Given the following features, what type of graft rejection is occuring? 

Occlusion of graft vessels causing ischemia and necrosis

  • Hyperacute rejection
  • Within minutes!
  • Antibody mediated (type II) due to presence of preformed anti-donor antibodies in transplant recipient


$ Types of Hypersensitivities

  • Anphylactic and Atopic (type I) - free antigen cross links IgE on presensitized mas cells and basophils, releasing vasoactive amines acting on postcapillary venules.
  • Cytotoxic (antibody mediated) (type II) - IgM, IgG bind and fix cell leading to lysis, recruit neutrophils and macrophages do most damage.
  • Immune complex (type III) - Antigen-antibody (IgG) complexes activate complement, attracts neutorphils -> release lysosomal enzymes
  • Delayed (cell mediated) (type IV) - Sensitized T lymphocytes encounter antigen and then release lymphokines (leads to macrophage activation; no antibody)


4 T's of Type IV hypersensitivity

  • T lymphocytes
  • Transplant rejections
  • TB skin tests
  • Touching ( contact dermatitis)


What causes more eosinophils in circulation?

DNAAACP + IL-5 (snot interleukin)

  • Drugs
  • Neoplastic
  • Asthma , Atopic, Allergic processes, Churg strauss
  • Addison's
  • Acute interstitial nephritis
  • Collagen vascular diseases
  • Parasites (invasive)


$$$ Bruton Agammaglobulinemia

  • X-linked (Boys)
  • B cell deficiency -> defective tyrosine kinase gene (BTK) -> low levels of all immunoglobulins
  • Recurrent Bacterial infections after 6 months
  • Absent thymic shadow


$$$ Thymic plasia (DiGeorge)

  • 3rd and 4th pouches fail to develop
  • No thymus -> No T cells
  • No parathyroids -> low Ca2+ -> tetany
  • Congenital defects in heart/great vessels
  • Recurrent viral, fungal protozoal infections
  • 90% have a chrom 22q11 deletion (detect with FISH)
  • Absent thymic shadow on CXR


$$$ Triad seen in SCID

1. Severe recurrent infections 

  • Chronic mucocutaneous Candidiasis
  • Fatal or recurrent RSV, VZV, HSV, measles, flu, parainfluenza
  • PCP pneumonia

2. Chronic diarrhea

3. Failure to thrive


$$$ Whatis SCID?

Severe Combined Immunodeficiency (SCID)

  • Defect in early stem cell differentiation
  • Can be caused by at least 7 different gene defects:
    • IL-2 receptor (most common, X-linked) -> T cells don't activate
    • Adenosine deaminase deficiency - increased adenine is toxic to B and T cells
  • Failure to synthesize MHC II antigens
  • Last defense is cytotoxic NK cells
  • TRIAD - Recurrent infection, CD, FtT
  • No thymic shadow on newborn CXR
  • Treatment: Bone marrow transplant



$$$ Chronic Mucocutaneou Candidiasis

  • T cell dysfunciton v. C. albicans
  • Recurent RSV, VZV, HSV
  • Rx: Ketoconazole


$$$ What are the X-linked Immunodeficiencies?

X-linked are "WBC H"


  • Wiskott-Aldrich
  • Bruton Agammaglobulinemia
  • Chronic Granulomatous Disease (+/-)
  • Hyper-IgM syndrome (3 types), all increased IgM and reduced Ig
    • X-linked -> No CD ligand
    • AR -> no CD40
    • -NEMO deficiency


$$$ Wiskott Aldrich



  • Wiskott
  • Aldrich
  • Immunodeficiency - pregressive deletion of B and T cells
  • Thrombocytopenia and purpura
  • Eczema
  • Recurrent pyogenic infections
    • No IgM v. capsular polysacchraides of bacteria - Strep, Staph, Haemophilus, Moraxella
    • Low IgM, high IgA, IgE
    • X-linked
  • Triad = TIE: Thrombocytopenic purpura, Infections, Eczema


$$$ Ataxia-Telangiectasia

Triad: AAA

Cerebellar defects (Ataxia)

Spider Angiomas (telangiectasia)

IgA deficiency

  • Defects in ATM gene - codes for DNA repair enzymes
  • Cerebellar ataxia, and poor smooth pursuit of moving target w/ eyes
  • Telangiectasias of face > 5yo
  • ↑ cancer risk: lymphoma & acute leukemias
  • Radiation sensitivity (avoid X-Rays)
  • ±↑AFP in chlidren >8m
  • Average age of death: 25 y/o


$$$ Selective Immunoglobulin Deficiencies

IgA deficiency is most common

  • Defect in isotype switching
  • Most appear healthy
  • Sinus and lung infections
  • 1/600 European descent
  • Associated with atopy, asthma
  • Possible anaphylaxis to blood transfusions and blood producs with IgA


$ IL-12 receptor deficiency

Mycobacterial infections

Reduced Th1 response -> reduced IFN-gamma


$$$ Phagocyte Deficiencies

  • Chronic granulomatous disease
  • Chediak-Higashi syndrome
  • Job syndrome
  • Leukocyte adhesion deficiency syndrome


$$$ Chronic Granulomatous Disease (CGD)

  • Lack of NADPH oxidase activity -> impotent phagocytes
  • Susceptible to organisms with catalase (S. aureus, E. coli, Klebsiella spp., Aspergillus spp., Candida spp.)
  • Dx: (-) nitroblue tetrazolium (NBT) dye - No yellow to blue-black oxidation (healthy phagocytes oxidize yellow dye to blue)
  • Prophylactic TMP-SMX
  • INF-gamma also helpful


$$$ Chediak-Higashi Syndrome

  • Defective LYST gene (lysosomal transport)
  • Defective phagocyte lysosome (microtubule dysfunciton in phagosome-lysosome fusion) -> giant cytoplasmic graules in PMNs are diagnostic
  • Presentation triad:
    • Partial albinism
    • Recurrent respiratory tract and skin infections - Pyogenic infections by staph, strep
    • Neurologic disorders - Peripheral neuropathy, seizures


$$$ Hyperimmunoglobulin E Syndrome

Job Syndrome - "FATED"
  • coarse Facies
  • cold (noninflamed) staphylococcal Abscesses
  • retained pirmary Teeth
  • ↑ IgE
  • Dermatologic problems (eczema)
  • Hyperimmunoglobulin E syndrome
  • Deficient INF-gamma (T-cells don't make any)-> PMNs fail to respond to chemotactic stimuli (C5a, LTB4)
  • High levels of IgE and Eosinophils
  • Presentation triad:
    • Eczema
    • Recurrent cold (no IL-1) staph. aureus abscesses (think of bibilical Job with boils
    • Course facial features: broad nose, prominent forehead ("frontal bossing"), deep set eyes, and "doughy" skin
    • Also common to have retained primary teeth resulting in 2 rows of teeth


$$$ Leukocyte Adhesion Deficiency Syndrome

  • Abnormal integrins (Defect in LFA-1 integrin (CD18) protein on phagocytes -> Inability of phagocytes to exit circulation
  • Delayed separation of umbilicus
  • Recurrent bacterial infections 
  • Absent pus formation
  • Neutrophilia


Child with staph abscesses, if the neutrophils fail to respond to chemotactic stimuli, what is the most likely diagnosis?

Job Syndrome (Hyperimmunoglobulin E syndrome)


Which embyonic germ layer is the thymus derived from?



Newborn with chronic diarrhea, failure to hrive and chronic Candida



Child with eczema, course facial features, cold abscesses

Hyper-IgE Syndrome (job syndrome)


Child with partial albinism, peripheral neuropathy, and recurrent infections

Chediak-Higashi Syndrome