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87 Cards in this Set

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Bruton's agammaglobulinemia
Defect- X-linked recessive. Defect in BTK (Tyrosine kinase gene) that blocks B-cell differentiation.
Presentation- Recurrent bacterial infections after 6 months due to opsonization defect
Lab- Normal pro-B, decreased maturation/number of B cells/all Ig classes
Hyper-IgM syndrome
Defect- Defective CD40L on Th cells so B cells cannot class switch.
Presentation- Severe pyogenic infections early in life
Lab- Increased IgM, markedly decreased IgG, IgA, IgE
Selective Ig Deficiency
Defect- Defect in isotype switching resulting in deficiency in a specific class of Igs
Presentaiton- Sinus and lung infections, milk allergies, associated with asthma and atopy, diarrhea, Anaphylaxis on exposure to blood products with IgA (form IgG against IgA). Giardia infection
Lab- IgA deficiency most common, decreased secretory IgA
Common variable immunodeficiency (CVID)
Defect- Defect in B-cell maturation
Presentation- Can be acquired in 20s-30s; increased risk of autoimmune disease, lymphoma, sinopulmonary infections.
Lab- Normal number of B cells; Decreased plasma cells and Ig
Thymic aplasia (DiGeorge syndrome)
Defect- 22q11 deletion; failure to develop 3rd and 4th pharyngeal pouches
Presentation- Tetany (hypocalcemia) seen by Chovstek and Trousseau's signs, recurrent viral/fungal/protozoan/intracellular infections (T-cell deficiency), congenital heart and great vessel defects
Lab- Thymus and parathyroids fail to develop so Decreased T cells, Decreased PTH, decreased Ca, absent thymic shadow on CXR
IL-12 receptor deficiency
Defect- Decreased Th1 response
Presentation- Disseminated mycobacterial infection
Lab- Decreased INF-G
Hyper-IgE syndrome (Job)
Defect- Th cells fail to produce IFN-G so neutrophils cannot respond to chemotactic stimuli (C5a, LTB4)
Presentation- Course facies (broad nose, frontal bossing, deep set eyes, doughy/thick skin), cold straph abscesses, retained primary teeth (2 rows), increased IgE, Eczema
Lab- Increased IgE
Chronic mucocutaneous candidiasis
Defect- T cell dysfunction
Presentation- Candida albicans infections of skin and mucous membranes
Severe combined immunodeficiency (SCID)
Defect- Several types including defective IL-2 receptor (most common, X-linked), adenosine deaminase deficiency, failure to synthesize MHC II antigens. Need to use NK cells
Presentation- viral (RSV, VZV, HSV, measles, PCP!!), bacterial, funal, and protozoan infections due to both B- and T-cell deficiency. Thymic hypoplasia, FTT, chronic diarrhea. NEED BM transplant!
Lab- Decreased IL-2R, increased adenine, decreased dNTPs and DNA synthesis also
Ataxia-Telangectasia
Defect- Defect in DNA repair enzymes
Presentation- Triad of cerebellar defects (ataxia) and poor smooth pursuit of moving objects with eyes, spider angiomas (telangectasia), IgA deficiency. Increased risk for acute lymphoma and leukemias
Lab- IgA deficiency, Increased AFP
Wiskcott-Aldrich syndrome
Defect- X linked recessive defect resulting in progressive deletion of B and T cells
Presentation- Triad of thrombocytopenic purpura, infections (encapsulated Nesseria, H. flu, S. pneumo), and eczema
Labs- Increased IgE, IgA, decreased IgM!!!
Leukocyte adhesion deficiency (type 1)
Defect- LFA-1 integrin (CD18) protein on phagocytes. Phagocytes cannot exit into the circulation.
Presentation- Recurrent bacterial infections, absent pus formation, delayed separation of the umbilicus
Labs- Neutrophilia
Chediak-Higashi Syndrome
Defect- AR defect in microtubular function with decreased phagocytosis. Cannot get degradative enzymes in lysosomes because of a LYST gene mutation.
Presentation- Recurrent pyogenic infections by Staph, Strep, partial albinism, peripheral neuropathy (seizures)
Lab- Neutrophils have large granules.
Chronic granulomatous disease
Defect- Lack of NAPDH oxidase leads to increased reactive oxygen species and absent respiratory burst in neutrophils.
Presentation- Increased susceptibility to catalase positive (S. aureus, E. coli, Aspergillus, candida) organisms
Lab- Negative Nitroblue tetrazolium dye reduction test (does not make the yellow to blue-black color change)
What actually causes LAD?
Massive enlargement of the paracortex of lymph nodes during an extreme cellular response. Not well developed in DiGeorge Syndrome.
What is the lymph node drainage site for the upper limb and lateral breast?
Axillary
What is the lymph node drainage site for the stomach?
Celiac
What is the lymph node drainage site for the duodenum and jejunum?
Superior mesenteric
What is the lymph node drainage site for the sigmoid colon
Colic to the inferior mesenteric
What is the lymph node drainage site for the rectum? above the pectinate line
Internal iliac, anal canal
What is the lymph node drainage site for the testes?
Superficial and deep plexuses ---> para-aortic!!!!
What is the lymph node drainage site for the scrotum, distal 1/3 of the vagina, vulva, and thigh?
Superficial inguinal
What is the lymph node drainage site for the lateral side of the dorsum of the foot?
Popliteal
What is the lymph node drainage site for the right arm and right half of head?
Right lymphatic duct
What bacteria do macrophages in the spleen remove?
Salmonella
S. pneumoniae
H. influenzae
N. meningitidis

(encapsulated)
Where does positive and negative selection occur in the thymus?
At the corticomedullary junction- the medulla has mature T cells and is pale (negative). The cortex has immature T cells, epithelial reticular cells, and Hassall's corpuscles, and is dense (positive).
What do MHC I proteins mediate?
Viral immunity; Antigen is loaded in the RER of intracellular peptides. It pairs with beta2-microglobin. Single heavy-chain and highly polymorphic.
What do MHC II proteins mediate?
Pathogens in endosomal compartments of APCs (phagocytosed bacteria). The antigen is loaded following release of invariant chain in acidified endosme.
What enhances the activity of NK cells?
IL-12, IFN-beta, IFN-alpha
What are the 2 signals for helper T-cell activation?
Signal 1: Foreign Ag present on MHC II
Signal 2: B7 on MHC II with CD28 on TH cell
What are the signals for cytotoxic T cell activation?
Signal 1: Endogenously synthesized or viral Ag presented on MHC I
Signal 2: IL-2 from Th cell activates Tc to kill the virus-infected cell
What are the signals for B-cell class switching?
Signal 1: IL-4/5/6 from Th2 cell
Signal 2: CD40L on Th cell binds CD40 on B cell
How to cytotoxic T cells kill virus-infected, neoplastic, or donor graft cells?
They release granules containing perforin (helps deliver granules to into target cells), granzyme (serine protease, activates apoptosis- via the extrinsic pathway), and granulysin (antimicrobial, induces apoptosis)
What is the Fab segment of an Ig?
Antigen-binding fragment: consists of 2LC + 2HC
Determines the idiotype (unique antigen binding pocket)
What is the Fc segment of an Ig?
2 HC
Constant, carboxy terminal (binds FcR) complement binding site at CH2 (for IgG and IgM), carbohydrate side chains, determines isotype
What are the features of IgG?
-Main Ab in delayed response to an antigen (secondary)
-Most abundant in blood (half life is 23 days)
-Crosses the placenta
-Fixes complement
-Opsonizes bacteria, neutralizes bacterial toxins and viruses
What are the features of IgA?
-Prevents attachment of bacteria and viruses to mucous membranes
-Monomer in circulation, but dimer when secreted (picks up secretory component from epithelial cells before secretion)
-Found in secretions and breast milk
What are the features of IgM?
-Produced in the immediate (primary) response to an antigen
-Fixes complement
-Antigen receptor on the surface of B cells
-Monomer on B cell or pentamer
What are the features of IgD?
-Unclear but found on the surface of many B cells and in serum.
-Periodic fever syndromes have increased IgD
What are the features of IgE?
-Binds mast cells and basophils via Fc region
-Cross links when exposed to an allergen, mediating type I hypersensitivity via histamine release
-Mediates immunity to worms by activating eosinophils
-Lowest serum concentration
What are thymus-independent antigens?
Antigens that lack a peptide component so they cannot be presented by MHC to T cells (ex: LPS). They stimulate the release of IgM antibodies ONLY and no memory
What are thymus-dependent antigens?
Antigens that contain a protein component (conjugated vaccine) are presented to Th-cells by MHC II and the Th-cell is activated. The activated Th-cell then binds B-cells that are also presenting the antigen, resulting in class switching and memory
What are the 2 primary opsonins in bacterial defense?
IgG and C3b (C3b also aids in clearance of the immune system)
What complement proteins mediate anaphylaxis?
C3a and C5a
What does MAC (C5b-9) do?
It causes cytolysis of plasma membrane to defend against GN bacteria.
What disease is caused by C1 esterase deficiency (catalyzes the first step of the classic pathway, prevents complement activation on self cells)
Hereditary angioedema
What happens in C3 deficiency?
Severe, recurrent pyogenic sinus and respiratory tract infections, increased susceptibility to type III hypersensitivity (esp glomerulonephritis) reactions.
What happens in deficiency of C5-C8?
Neisseria bacteremia
What does deficiency of DAF (CD55 + CD59) cause?
PNH- complement mediated lysis of RBCs
What does IL-12 do?
Induces differentiation of T cells into TH1 cells and activates NK cells. Patients deficient in IL-12 can receive IFN-gamma
What cytokines mediate inflammation?
IL-1 (pyrogen, activates endothelium to express adhesion molecules, recruits leukocytes by inducing chemokine secretion)
IL-6 (pyrogen, stimulates production of acute-phase proteins)
TNF-a (Septic shock; activates endothelium, leukocyte recruitment, vascular leak, cachexia)
IL-10 (modulates it by inhibiting action of Th1 cells)
What does IFN-g do?
-Activates macrophages and Th1 cells; suppresses Th2 cells; granuloma formation.
-Antiviral- increases MHC I and II expression and antigen presentation in all cells, induces production of ribonuclease that inhibits viral protein synthesis by degrading viral mRNA
-Antitumor
What does IL-4 do?
Induces differentiation of Th2 cells, B cell growth, class switching to IgE and IgG
What does IL-5 do?
Induces class switching to IgA, stimulates growth and differentiation of eosinophils.
What do IFN-a and IFN-b do?
-Induces production of ribonuclease that inhibits viral protein synthesis by degrading viral mRNA
-Activate NK cells to kill virus-infected cells
What surface proteins are found on macrophages?
MHC II, B7, CD40, CD14 (binds LPS in a T-independent response), FcR, C3bR
What surface proteins are found on B cells?
Ig, CD 19, CD20, CD21 (receptor for EBV), CD40, MHC II, B7
What surface proteins are found on Th cells?
TCR, CD3, CD40L, CD28, CD4
What surface proteins are found on Tc cells?
TCR, CD3, CD28, CD8
What surface proteins are found on NK cells?
Receptors for MHC I, CD16 (binds Fc of IgG), CD56
What are the only cells that do not express MHC I?
RBCs
How do endotoxins/LPS activate macrophages?
Directly bind to CD14 (T-independent)
What organisms express antigenic variation?
Salmonella (2 flagellar variants)
Borrelia (relapsing fever)
N. gonorrhoeae (pilus)
Influenza
Trypanosomes (programmed rearrangement)
When should you give passive immunity?
After exposure to tetanus toxin, botulinum toxin, HBV, rabies (in addition to vaccines)

To Be Healed Rapidly
What is type II sensitivity?
SELF-antibodies (IgM or IgG) bind to FIXED antigens on cell surfaces.
-Opsonize cells or activate complement
-Recruit neutrophils or macrophages to cause tissue damage
-Bind to normal cell receptors and interfere with functioning

Test: Coombs
What is type III sensitivity?
Antigen-antibody complexes are deposited in membranes, where they fix complement and incite tissue damage by attracting neutrophils (release lysosomal enzymes).

Test: Immunofluorescent staining
What is serum sickness?
A type of type III hypersensitivity characterized by fever, urticaria, arthralgias, proteinuria, glomerulonephritis, vasculitis (fibrinoid necrosis), LAD 5-10 days after antigen exposure, leads to hypocomplementemia. Sulfonamides can cause this
What is the arthus reaction?
Intradermal infection of an antigen induces IC to form in the skin, causing edema, necrosis, and complement activation.

Ex- Tetanus shot
What are examples of Type I hypersensitivity?
Anaphylaxis, allergic and atopic disorders (rhinitis, hay fever, eczema, hives, asthma)
What are examples of Type II hypersensitivity?
Hemolytic anemia, pernicious anemia, ITP, erythroblastosis fetalis, ACUTE hemolytic transfusion reactions (diff blood types), rheumatic fever, Goodpasture's, Bullous pemphgoid, Pemphigus vulgaris, Graves, MG
What are examples of Type III hypersensitivity?
SLE, Rheumatoid arthritis, PAN, APSGN, serum sickness, arthus reaction, hypersensitivity pneumonitis, Churg-Strauss
What are examples of type IV hypersensitivity?
Type I DM, MS, GBS, Hashimoto's, GVHD, PPD, contact dermatitis, sarcoidosis, candida extract skin reaction
What is seen in acute transplant rejection?
Cytotoxic T cell mediated; reversible with immunosuppressants; There is vasculitis of graft vessels with dense interstitial lymphocyte infiltrate.
What is seen in chronic transplant rejection?
T-cell and antibody mediated vascular damage (obliterative vascular fibrosis); irreversible; bronchiolitis obliterans; fibrosis of vessels and tissue
What is seen in GVHD?
Graft T-cells proliferate and reject host proteins- see maculopapular rash, jaundice, HSM, and diarrhea. usually occurs in BM and liver transplant.
What is the lymph drainage site for the proximal 2/3 of the vagina and uterus?
Obturator, external iliac, and hypogastric nodes
What cell type is present in the following lymph node regions?

Follicles
Paracortex
Medullary cords
Medullary sinus
Follicles- B cells isotype switching and proliferating
Paracortex- T cells; contains High endothelial venules
Cords- Plasma cells
Sinuses- Macrophages and reticular cells
What is the lymph drainage site for the anal canal below the pectinate line?
Superficial inguinal
HLA A3
Hemochromatosis
HLA B27
Psoriasis, ankylosing spondylitis, IBD, Reiter's syndrome
HLA B8
Graves' disease
HLA DR2
MS, Hay fever, SLE, Goodpasture's
HLA DR3
DM1
HLA DR4
RA, DM1
HLA DR5
Pernicious anemia, Hashimoto's
HLA DR7
Steroid-responsive nephrotic syndrome
What do C1-C4 in the complement cascade do?
Viral neutralization