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Immunology Flashcards

1
Q

Part of lymph node cortex…
Contains germinal center
B-cell localization and proliferation

A

FOLLICLE

Secondary follicles have pale germinal center surrounded by mantle and are active

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2
Q

Part of lymph node containing…
Cords of closely packed Lymphocytes/Plasma Cells
Sinuses containing Reticular Cells/Macrophages
Communication with efferent lymphatics

A

MEDULLA

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3
Q

Part of lymph node between Follicles and Medulla…
Houses T cells
Contains high endothelial venules from which T/B cells can enter from the blood

A

PARACORTEX

Enlarges with viral infection

Not well developed in patients with DiGeorge syndrome

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4
Q

Drainage of trachea and esophagus.

A

Mediastinal lymph nodes.

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5
Q

Drainage of upper limb, breast, and skin above umbilicus.

A

Axillary lymph nodes.

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6
Q

Drainage of liver, stomach, spleen, pancreas, and upper duodenum.

A

Celiac lymph nodes.

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7
Q

Drainage of lower duodenum, jejunum, ileum, and colon to splenic flexure.

A

Superior mesenteric lymph nodes.

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8
Q

Drainage of colon from splenic flexure to upper rectum.

A

Inferior mesenteric lymph nodes.

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9
Q

Drainage of lower rectum to anal canal above pectinate line, bladder, vagina, cervix, and prostate.

A

Internal iliac lymph nodes.

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10
Q

Drainage of testes, ovaries, kidneys, and uterus.

A

Para-aortic lymph nodes.

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11
Q

Drainage of anal canal below pectinate line, skin below umbilicus, scrotum, and vulva.

A

Superficial inguinal nodes.

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12
Q

Drainage system of right side of body above diaphragm.

A

Right lymphatic duct.

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13
Q

Drainage system emptying into left subclavian and internal jugular veins.

A

THORACIC DUCT

Drains everything not drained by the right lymphatic duct

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14
Q

Location of T cells in the spleen.

A

Periarteriolar lymphatic sheath (PALS) in white pulp surrounding central arteriole.

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15
Q

Location of B cells in the spleen.

A

Follicles in white pulp between PALS and marginal zone.

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16
Q

Location in spleen where APCs capture blood-borne antigens for presentation.

A

MARGINAL ZONE

Between red pulp and white pulp

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17
Q

Mechanism of encapsulated bacteremia due to splenic dysfunction.

A

Decreased IgM
Decreased complement activation
Decreased C3b opsonization
Increased susceptibility to encapsulated organisms

("Please SHiNE my SKiS")
Pseudomonas
S. pneumo
HIB
Neisseria
E. coli
Salmonella
Klebsiella
gbS
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18
Q

Howell-Jolly bodies
Target cells
Thrombocytosis
Lymphocytosis

A

Asplenia

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19
Q

Embryologic origin of thymus.

A

Third pharyngeal arch

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20
Q

Hypoplastic thymus.

A

DiGeorge syndrome

SCID

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21
Q

Enlarged thymus.

A

Myasthenia gravis.

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22
Q

Mechanism of pathogen recognition by the innate immune system.

A

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) such as LPS, flagellin, and nucleic acids.

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23
Q

MHCI gene loci.

A

HLA-A/B/C

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24
Q

MHCII gene loci.

A

HLA-DP/DQ/DR

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25
Cells expressing MHCI
All nucleated cells - Except RBCs
26
Cells expressing MHCII
APCs
27
Presents endogenously synthesized antigens (viral, cytosolic proteins) to CD8+ cytotoxic T cells.
MHCI Antigens loaded in RER after delivery via TAP - associated with B2-microglobulin
28
Presents exogenously synthesized antigens (bacterial proteins) to CD4+ helper T cells.
MHCII Antigen loaded following release of invariant chain in acidified endosome. Note - Made of a/b polypeptide chains
29
``` Hemochromatosis Addison's Myasthenia Gravis Celiac MS Hay fever Goodpasture SLE Graves T1DM Hashimoto's Rheumatoid Arthritis Pernicious Anemia Steroid responsive nephrotic syndrome ```
``` HLA-A3 HLA-B8/DR3/DR4 HLA-B8 HLA-DQ2/8 HLA-DR2 HLA-DR2 HLA-DR2 HLA-DR2/3 HLA-DR3 HLA-DR3/4 HLA-DR3/5 HLA-DR4 HLA-DR5 HLA-DR7 ```
30
Diseases ("PAIR") associated with HLA-B27 - also known as the seronegative arthropathies.
Psoriatic arthritis Ankylosing spondylitis IBD-associated arthritis Reactive arthritis (Reiter syndrome)
31
Activated when exposed to non-specific activation signal, or decreased MHCI expression on target cell (e.g. malignancy, viral) Express CD16 (Fc of IgG), CD56 (unique) Secretes IFN-y
NATURAL KILLER CELL Induced by IL-2, IL-12, IFN Note - Do not require thymic maturation and so found in athymic patients
32
Mechanism of NK cell action.
Perforins allow entry of granzymes and induce apoptosis in virally infected cells and tumor cells (lack MHCI) Also kills via antibody-dependent cell-mediated cytotoxicity - CD16 binds Fc region of bound Ig activating NK cell
33
Mechanism of B-cell maturation
Precursors in bone marrow (VDJ recombination) Migration to lymph nodes/peripheral tissues Antigen exposure Some become temporary Plasma Cells secreting IgM Most travel to germinal centers for proliferation Class switching/Somatic hypermutation Note - Majority of opsonizing antibodies produced in spleen
34
Sites of T cell maturation.
Precursor in bone marrow CD4/8+ in thymic cortex CD4+ or CD8+ in thymic medulla Cytotoxic or Helper (TH1, TH2, TH17) in lymph node
35
Mechanism of positive selection (thymic cortex).
Only T cells expressing TCRs capable of binding self-MHC survive.
36
Mechanism of negative selection (thymic medulla).
T cells expressing TCRs with high affinity for self antigens undergo apoptosis - allows for self-tolerance.
37
Inability to express tissue-restricted self-antigens in the thymus due to deficient AIRE.
Autoimmune polyendocrine syndrome 1
38
``` Activates... Macrophages Cytotoxic T cells NK cells MHC expression by all cells ``` Secretes IFN-y
TH1 CELL Induced by IL-12 (macrophages), IFN-y (self) Inhibited by IL-4, IL-10 (TH2 cell, Treg)
39
Recruits eosinophils for parasite defense and promotes IgE/A production by B cells Secretes IL-4, IL-5, IL-10, and IL-13
TH2 CELL Induced by IL-4 (self) Inhibited by IFN-y (TH1 cell)
40
Macrophage-lymphocyte interaction mechanism.
Macrophages/APCs release IL-12 which induces TH1 cells TH1 cells in turn secrete IFN-y to stimulate macrophages - also inhibits TH2 cells, induced NK cells, and increases MHC expression
41
Mechanism of cytotoxic (CD8) T cells.
Release cytotoxic granules containing perforin and granzyme to induce apoptosis in virally infected, tumor, and donor graft cells.
42
Express CD4, CD25, and FOXP3 Produce IL-10, TGF-b (anti-inflammatory)
REGULATORY T CELLS Maintain immune tolerance by suppressing CD4/8 T cell effector function
43
Mechanism of T cell activation (2 signals).
Dendritic cell migrates to draining lymph node Antigen presented via MHC and TCR (signal 1 - activation) Interaction of B7 (CD80/86) and CD28 (signal 2 - proliferation)
44
Mechanism of B cell activation (2 signals).
B-cell receptor-mediated endocytosis allows presentation of antigen via MHCII Activated Th cell binds MHCII via TCR (signal 1) CD40L on Th cell binds CD40 on B cell (signal 2) Th cell secretes cytokines B cell activates and undergoes class switching, affinity maturation, and Ig production
45
Mechanism of antibody diversity (antigen independent).
Random recombination of VJ (light-chain) or V(D)J (heavy-chain) genes Random addition of nucleotides to DNA during recombination by terminal deoxynucleotidyl transferase (TdT) Random combination of heavy chains with light chains
46
Mechanism of antibody specificity (antigen dependent).
Somatic hypermutation (variable region) and clonal proliferation leading to affinity maturation Isotype/class switching (constant region)
47
Express IgM and IgD.
Naive B cells
48
CD responsible for mediating isotype/class switching.
CD40 (+cytokines)
49
``` Monomer Fixes complement Opsonization (with C3b) Neutralizes bacterial toxins and viruses Cross placenta (infant passive immunity) ```
IgG Most abundant serotype in plasma
50
Monomer in circulation Dimer (J chain) when secreted Does not fix complement Produced in GI tract (Peyer's patches; prevents Giardia) Released into tears, saliva, mucous, breast milk Prevents attachment of bacteria and viruses to mucous membranes
IgA Most produced antibody but low serum concentrations Crosses epithelial cell by transcytosis, and picks up secretory component from epithelial cells which protects Fc portion from luminal proteases
51
Monomer as antigen receptor on B cell Pentamer (J chain) when secreted Fixes complement Does not cross placenta
IgM
52
Binds mast cells and basophils, then crosslinks when exposed to allergen to allow for release of inflammatory mediators (e.g. histamine) Mediates immunity to worms by activating eosinophils
IgE Lowest serum concentration
53
Antigens lacking a peptide component (LPS) Cannot be presented by MHC to T cells Only IgM is produced
THYMUS-INDEPENDENT ANTIGENS Protein conjugate helps initiate T-cell dependent stimulation of B lymphocytes - Results in memory cell response and thus longer duration of immunity (e.g. LPS, Polysaccharide-Conjugate vaccines) Note - Humoral immunity is weak < 2 mo of age and so this is particularly important in newborns
54
Antigens containing a protein component Direct contact of B cells with Th cells Class switching and immunologic memory occur
THYMUS-DEPENDENT ANTIGENS E.g. Diphtheria vaccine Note - Also provides mucosal immunity (herd immunity)
55
Induced by IL-6 and produced in the liver.
Acute phase reactants
56
Positive (upregulated) acute phase reactants.
CRP - opsonin (complement fixation, phagocytosis) Ferritin - binds and sequesters iron Fibrinogen - endothelial repair (ESR) Serum amyloid A - leads to amyloidosis Hepcidin - degrades ferroportin (decreased Fe absorption and release from macrophages)
57
Negative (downregulated) acute phase reactants.
Albumin - reduced to conserve AA for positive reactants | Transferrin - Internalized by macrophages to sequester Fe
58
Classic (antigen-antibody) and Lectin (microbial surface) complement cascade.
``` C1 binds near hinge of IgM or IgG Forms C2b and C4b C3 convertase (C4b2b) Forms C3b C5 convertase Forms C5b With C6-C9 forms MAC - lysis and cytotoxicity (Gram-) ```
59
Alternative (spontaneous and microbial surface) complement cascade.
C3 forms C3b C3 convertase (C3bBb) Forms C3b
60
Function of C3a, C4a, C5a formed by complement cascade.
Anaphylaxis Note - C5a also responsible for neutrophil chemotaxis
61
Inhibitors of complement cascade on self cells (e.g. RBCs).
DAF (CD55) - prevents formation of C3 convertase | C1 esterase inhibitor
62
``` Episodes of... Non-pitting edema Respiratory obstruction Abdominal pain No pruritus or urticaria ```
HEREDITARY ANGIOEDEMA Autosomal dominant C1 esterase inhibitor deficiency leads to increased conversion of Kallikrein to Bradykinin and activation of classical complement cascade - angioedema Do not give ACEi
63
Increases risk of severe, recurrent pyogenic sinus and respiratory tract infections Increases susceptibility to type III hypersensitivity
C3 DEFICIENCY
64
Complement deficiency increases susceptibility to recurrent Neisseria bacteremia.
C5-C9 DEFICIENCIES
65
Causes complement mediated lysis of RBCs and paroxysmal nocturnal hemoglobinuria.
DAF DEFICIENCY GPI-anchored enzyme
66
Function of macrophage secreted ILs... IL-1 IL-6 IL-8 IL-12 TNF-a
IL-1 (OAF) = Adhesion molecules, Chemokine secretion IL-6 = APR IL-8 = Chemotactic IL-12 = Th1, NK TNF-a = Septic shock, Cachexia (wasting due to underlying systemic disease), systemic inflammatory response
67
Function of T cell secreted ILs... IL-2 IL-3
IL-2 = Induces all T cells, NK cells, B cells, macrophages. If present for lengthy period can promote FAS mediated apoptosis IL-3 = Like GM-CSF (stimulates stem cell production of granulocytes and monocytes)
68
Function of TH2 secreted ILs... IL-4 IL-5 IL-10
IL-4 = Induces Th2 cells, B cells, switching to IgE/G IL-5 = Induces Eosinophils, B cells, switching to IgA IL-10 = Inhibits Th1, APCs, MHCII (with TGF-B)
69
Respiratory (oxidative) burst pathway in phagocytes (neutrophils, monocytes).
O2 + NADPH to Superoxide (NADPH oxidase) Superoxide to H2O2 (Superoxide dismutase) H2O2 + Cl to Hypochlorite (Myeloperoxidase) Note - MPO blue-green heme containing pigment gives sputum its color ``` H2O2 reduced (Glutathione peroxidase) Glutathione replenished (Glutathione reductase+NADPH) NADPH from HMP shunt replenished (G6PD) ``` Note - Superoxide dismutase is technically an antioxidant as its product (H2O2) is eliminated by Glutathione Peroxidase and Catalase
70
Mechanism of catalase+ infections in patients with CGD (NADPH oxidase deficiency).
Phagocytes can utilize H2O2 from invading organisms (downstream of NADPH oxidase) - catalase+ organisms clear their own H2O2.
71
Glycoproteins synthesized by virally infected cells that act locally on uninfected cells - Selectively prevent viral translation
IFN-a and IFN-b monocytes, macrophages, B cells, NK cells.
72
``` Express... CD2 CD3 (transmit signals to cell interior) CD4/8 CD40L CXCR4 ```
Helper T cell (Th cell) - Cellular immune response Note - CD16/56 for NKC
73
``` Express... IgG MHCII B7 (CD80/86) for CD28 CD40 for CD40L CD19 CD20 CD21 for EBV ```
B cells - Humoral immune response
74
``` Express... MHCII B7 (CD80/86) for CD28 CD40 for CD40L TLR4 (CD14) for PAMPS/endotoxins Fc and C3b receptors CCR5 ``` Note - CCR5 is a G-protein chemokine receptor and requires co-binding with CD4 for HIV infection
Macrophages
75
Cell expressing... CD34 CD18
Hematopoietic stem cell | Neutrophils
76
Mechanism by which T and B cells become inactivated after binding to their antigen without a costimulatory signal (signal 2) - allows for self-tolerance.
Anergy
77
Exposures treated with preformed antibodies. | "To Be Healed Very Rapidly"
``` Tetanus Botulinum HBV (+active immunization) Varicella Rabies (+active immunization) ``` Other sources of preformed antibodies include IgA in breast milk and IgG crossing placenta
78
Mechanism of type I hypersensitivity - anaphylactic and atopic ``` Bee sting Food allergy Rhinitis Hay fever Eczema Hives Asthma ```
Free antigen crosslinks IgE on presensitized Mast cells and Basophils resulting in release of vasoactive amines (e.g. histamine) that act on postcapillary venules - rapid because of preformed antibodies Subsequent delayed response due to production of leukotrienes, prostaglandins, and cytokines by eosinophils Test for using skin test
79
Mechanism of type II hypersensitivity - cytotoxic/targeted Includes most inherited and acquired tissue specific hypersensitivities (e.g. hemolytic reactions/diseases)
Antibody (IgM, IgG) mediated cellular destruction by NKs, Neutrophils, Macrophages, and Eosinophils... Opsonization and phagocytosis Complement/Fc mediated inflammation Antibody-mediated inactivation Direct Coombs' detects antibodies that have adhered to a patient's RBCs using antihuman antibodies (test Rh+ infant) Indirect Coomb's detects antibodies that can adhere to other RBCs (test Rh- mother)
80
Mechanism of type III hypersensitivity - immune complex /systemic ``` Arthus reaction SLE Polyarteritis nodosa Post-strep glomerulonephritis Serum sickness ```
Antigen-antibody complex activates complement, which attracts Neutrophils and causes local inflammation Test for using immunofluorescent staining
81
``` 5-10 days after antigen exposure... Fever Urticaria Arthralgia Proteinuria Lymphadenopathy ```
SERUM SICKNESS Type III hypersensitivity in which antibodies to foreign proteins are produced - often caused by drugs
82
Following intradermal injection of antigen into a presensitized individual... Edema Necrosis
ARTHUS REACTION Local subacute type III hypersensitivity reaction
83
Mechanism of type IV (delayed) hypersensitivity - Cell mediated (T-cell, Macrophages) ``` Contact dermatitis (poison ivy, nickel allergy) TB skin test GVHD Granulomatous inflammation Multiple sclerosis ```
Sensitized T cells encounter an antigen and release cytokines leading to macrophage activation - does not involve antibodies and not transferable by serum Test with patch test (e.g. TB test)
84
``` Blood transfusion followed by... Urticaria Pruritus Wheezing Fever ```
Type I hypersensitivity - Allergic reaction against plasma proteins in transfused blood Treat with antihistamines
85
``` Blood transfusion followed by... Dyspnea Bronchospasm Hypotension Shock Cardiac arrest ```
Type I hypersensitivity - Anaphylaxis against IgA in IgA-deficient patients (require washed RBCs) Treat with epinephrine
86
``` Blood transfusion followed by... Fever Headache Chills Flushing ```
FEBRILE NONHEMOLYTIC TRANSFUSION REACTION Type II hypersensitivity - Host antibodies against donor HLA antigens and WBCs
87
``` Blood transfusion followed by... Chest or back pain Fever Hypotension Tachypnea Tachycardia Hemoglobinuria (intravascular hemolysis) Jaundice (extravascular hemolysis) ```
ACUTE HEMOLYTIC TRANSFUSION REACTION Type II hypersensitivity - ABO incompatibility (intravascular)
88
Anti-basement membrane
Goodpasture syndrome
89
Anti-centromere
Limited scleroderma (CREST)
90
Anti-glutamic acid decarboxylase (GAD-65)
T1DM
91
Anti-desmoglein (anti-desmosome)
Pemphigus vulgaris
92
Anti-hemidesmosome
Bullous pemphigoid
93
Anti-Jo-1, anti-SRP, anti-MI-2
Polymyositis, dermatomyositis
94
Anti-microsomal, antithyroglobulin
Hashimoto thyroiditis
95
Anti-mitochondrial
Primary biliary cirrhosis (PBC)
96
Anti-phospholipase A2 receptor
Primary membranous nephropathy
97
Anti-scl-70 (anti-DNA topoisomerase II)
Scleroderma (diffuse)
98
Anti-smooth muscle
Autoimmune hepatitis type 1
99
Anti-SSA, anti-SSB (anti-Ro, anti-La)
Sjogren's
100
IgA anti-endomysial, IgA anti-tissue transglutaminase
Celiac disease
101
MPO-ANCA/p-ANCA
Microscopic polyangiitis | Eosinophilic granulomatosis with polyangiitis (Churg-Strauss)
102
PR3-ANCA/c-ANCA
Granulomatosis with polyangiitis (Wegener)
103
``` Rheumatoid factor (IgM targeting IgG-Fc) Anti-CCP (specific) ```
Rheumatoid arthritis
104
After 6 months... Pyogenic infections Enteroviruses Giardia Absent B cells on peripheral smear (CD19 or CD20) Decreased IgA, IgM, IgG Absent/scant lymph nodes and tonsils
X-LINKED (BRUTON'S) AGAMMAGLOBULINEMIA X-linked recessive (common in boys) Defect in BTK (tyrosine kinase) leads to deficient B-cell maturation
105
Airway and GI infections Autoimmune disease (e.g. Celiac) Atopy Anaphylaxis to transfusion Decreased IgA Normal IgM, IgG
SELECTIVE IGA DEFICIENCY
106
``` Can be acquired in 20s and 30s Bronchiectasis Sinopulmonary infections Autoimmune disease Lymphoid hyperplasia of the intestines ``` Decreased plasma cells Decreased IgA, IgM, IgG
COMMON VARIABLE IMMUNODEFICIENCY
107
``` Tetralogy of Fallot/Truncus arteriosus Abnormal facies Recurrent viral and fungal infections Cleft palate Tetany ``` Decreased T cells Decreased PTH Hypocalcemia Absent thymic shadow on CXR
THYMIC APLASIA (DIGEORGE SYNDROME) Diagnosed by 22q11 deletion on FISH - failure to develop 3rd and 4th pharyngeal pouches leads to absent thymus and parathyroids B lymphocytes are adequate (CD20+) T lymphocytes are low (CD3+) - which are important in signaling B cells to develop into antibody producing plasma cells Thus at risk for viral, bacterial, and fungal infections
108
Disseminated mycobacterial and fungal infections - May be precipitated by BCG vaccine Decreased IFN-y
IL-12 RECEPTOR DEFICIENCY Autosomal recessive deficiency in IL-12 - Prevents dimerization of Janus Kinase (STAT1)
109
Coarse facies Noninflamed staph abscesses Retained primary teeth Eczema Increased IgE Decreased IFN-y
AUTOSOMAL DOMINANT HYPER-IgE (JOB) SYNDROME STAT3 mutation leads to deficiency of Th17 cells - impaired recruitment of neutrophils to sites of infection
110
Noninvasive candida albicans infections of skin and mucous membranes Absent in vitro T-cell response to candida antigens Absent cutaneous reaction to candida antigens
CHRONIC MUCOCUTANEOUS CANDIDIASIS T-cell dysfunction
111
``` Failure to thrive Chronic diarrhea Recurrent viral and opportunistic infections Candidasis Anergy ``` Decreased T-cell receptor excision circles Absent thymic shadow on CXR Absent germinal centers in lymph nodes Absent T cells (lymphopenia) Nonfunctional B cells (hypogammaglobulinemia)
SEVERE COMBINED IMMUNODEFICIENCY Defective IL-2 (X-linked) Defective Adenosine Deaminase deficiency (autosomal recessive) Bone marrow transplant - no concern for rejection Because lymphoid progenitor cells affected --> low B (CD20+) and T cells (CD3+)
112
Ataxia Telangiectasia Cerebellar atrophy Malignancy risk IgA deficiency --> repeated sinupulmonary infections Increased AFP Combined B/T cell defect
ATAXIA-TELANGIECTASIA Defect in ATM gene - Inability to repair dsDNA breaks (ionizing radiation) leads to cell cycle arrest
113
Failure to thrive Recurrent sinopulmonary/GI infections Opportunistic infections (Pneumocystis, Cryptosporidium, CMV) lack of IgG increases risk of encapsulated bacterial infection Normal or increased IgM Very decreased IgA, IgG, IgE
HYPER IGM SYNDROME X-linked recessive Defective CD40L on T helper cells leads to defective immunoglobulin gene rearrangement/class switching
114
Recurrent infections worsening with age (>6 mos) Bleeding (Thrombocytopenia) Eczema Small, decreased platelets Combined B/T cell defect
WISKOTT-ALDRICH SYNDROME X-linked recessive Mutation in WAS - Actin cytoskeletal defect in T cells
115
Recurrent bacterial skin and mucosal infections Absent pus formation Impaired wound healing Delayed separation of umbilical cord (>30 d) Increased neutrophils Absence of neutrophils at infection site
LEUKOCYTE ADHESION DEFICIENCY TYPE 1 Autosomal recessive Defect in LFA-1 product integrin-b2 (CD18) leads to impaired migration and chemotaxis
116
Recurrent pyogenic infections by staph/strep Partial albinism Peripheral neuropathy Progressive neurodegeneration Pancytopenia Giant granules in granulocytes and platelets
CHEDIAK-HIGASHI SYNDROME Autosomal recessive Defect in lysosomal trafficking regulator gene (LYST) - Microtubule dysfunction and phagosome-lysosome fusion
117
``` Increased susceptibility to catalase+ organisms... Lungs Skin Lymph nodes Liver ``` Recurrent bacterial infections ("New LiBrary SPACES") Abnormal dihydrorhodamine test (decreased green fluorescence) Lower blue score in nitroblue tetrazolium dye reduction test
CHRONIC GRANULOMATOUS DISEASE X-linked recessive - Defect in NADPH oxidase decreases superoxide and respiratory burst in neutrophils Treat with IFN-y ``` Nocardia Listeria Burkholderia cepacia Staphylococcus Pseudomonas Aspergillus Candida Enterobacteriaceae (E. coli, Serratia) ```
118
Within minutes to hours... Arterial fibrinoid necrosis Capillary thrombotic occlusion Gross mottling and cyanosis
HYPERACUTE REJECTION Type II hypersensitivity - Pre-existing recipient antibodies react to donor antigen and activate complement Graft must be removed
119
Within weeks to months... Endotheliitis with lymphocytic infiltrate OR Necrotizing vasculitis with neutrophilic infiltrate and C4d deposition
ACUTE REJECTION Type IV hypersensitivity - CD8+ T cells activated against donor MHCs Note - May also be humoral (Type II; antibodies develop after transplant) as well Prevent/reverse with immunosuppressants
120
Within months to years... Proliferation of vascular smooth muscle Parenchymal atrophy and interstitial fibrosis Dominated by atherosclerosis Bronchiolitis obliterans (lung) Accelerated atherosclerosis (heart) Chronic graft nephropathy (kidney) Vanishing bile duct syndrome (liver)
CHRONIC REJECTION CD4+ T cells respond to recipient APCs presenting donor peptides (e.g. allogeneic MHC) - both cellular (type II) and humoral (type IV) hypersensitivity
121
``` Transplant patient (liver or bone marrow) with... Maculopapular rash Jaundice Diarrhea Hepatosplenomegaly ```
GRAFT VERSUS HOST DISEASE Grafted immunocompetent T cells proliferate in immunocompromised host and reject host cells with "foreign" proteins leading to severe dysfunction - type IV hypersensitivity In bone marrow transplant may be potentially beneficial - graft versus tumor effect
122
Mechanism of immune response to parasites
Th2 cells and mast cells produce IL-5 IL-5 induces eosinophils Eosinophils bind to IgE on parasite and release major basic protein and ROS Antibody-dependent cell-mediated cytotoxicity Antigen presentation via MHCII
123
Main opsonins of the immune system
IgG | C3b
124
Mechanism of NF-kB action
Growth factor mitogens, Cytokine-TNFR binding, or antigen-TLR binding IkB kinase phosphorylates IkB NF-kB released and enters nucleus leading to transcription of inflammatory and proliferative genes

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