Immunology Innate Instrinsically (always on) Nonspecific No memory Limited diversity
Adaptive Inducible when needed Specific Memory SPECIFIC Self-limiting ( important to turn it off when its not needed)
* don’t forget forget skin, pH , chemicals like lyzosymes , compliment are all part of innate Innate and Adaptive work together Innate turns on Adaptive by antigen presentation Adaptive strengthens the innate by cytokines
Primary lymphoid: where B and T born : bone marrow and thymus Secondary : where activated - Spleen : blood borne pathogen - Lymph node: tissue tissue pathogen - Malt: mucous
Cell types
Cells always present in tissue 1. Macrophage (monocyte in the blood) 2. Mast cells 3. Dendritic cells Eosinophils -Kill parasites -also called in Type 1 hypersensitivity and have Histaminase ( break down histamine from mast) and release more Leukotrienes Mast cells + basophils in Type 1 hypersensitivity Dendritic cells -Langerhans cell in skin ( have Birbeck granules)
B and T cells -
Carboxy terminus of receptors goes into the membrane N terminus binds antigen
B cells -Idiotype : Variable region binds antigen ( N terminus) = heavy and light chain - Isotype : constant region that determines FUNCTION (C terminus) = heavy only B cell
T cell
MATURE naïve B cell: IgM and IgD on same cell - receptor valency 2 minimum - receptor is flexible bc of HINGE region formed from disulfide bonds Can secrete = antibodies Receptors bind everything Bind it by themselves Signal Transduction for cascade Ig-α and Ig-β two on each side, CD19, CD20 Heavy chain (VDJ) + Tdt Light chain ( VJ)
T cell receptor ( alpha and beta) -Valency 1 - not flexible bc no hinge Receptors ALWAYS CELL BOUND Receptors only bind PEPTIDES Require antigen presenting cell CD3 Beta chain (VDJ) + Tdt Alpha chain ( VJ) + Tdt Self limited by FAS (Activation induced cell death)
Production of chains B and T cell receptor Chain production The recombinase ( RAG 1 and RAG2) rearrange genes -VDJ a) D-J b) V-DJ - VJ Then transcription Then Alternative splicing for the different isotypes ( after the antigen is presented in the germinal center) -If naïve just get IgM first bc it’s the first one Diversity 1. Random gene rearrangements VDJ, VJ 2. Tdt insert random bases 3. Random combo of light and heavy chain for B, and alpha and beta for T -----4. ONLY B CELLS : SOMATIC HYPERMUTATION causing AFFINITY MATURATION in the cells that activated in germinal center, therefore secondary activation is strong
B cells
Heavy chain isotypes all on one chromosomes ( therefore 2 chances to rearrange, one from each parent) Light chain λ +κ on different chromosome ( 4 chances to rearrange) ALLELIC EXCLUSION: Once rearranged turn off the other gene so only ONE SPECIFICITY / CELL
Antigens for B and T cells B cells can bind anything VS T cells only bind peptides Thymus dependant antigens : peptides ( the B cells present these and causes strong immune response bc T cells help = isotype switch + memory)
Thymus independent antigen - Ex: polysaccharide capsule + LPS (gram -) - T cells not no (no CD40 ligand)= NO ISOTYPE SWITCH -NO MEMORY
Bcell development and selection
PRO- B: The cytoplasmic μ is the heavy chain waiting for the light chain to be made Negative selection in the Immature B cell when only surface IgM - clonal deletion of those that bind to tight Activated Blast is when ANTIGEN BINDS and causes proliferation in the GERMINAL CENTER -here somatic hypermutation -isotype switching The plasma cell is a dead end ( make Ig and then die in two weeks) Memory cells when activated 2nd directly to memory cell transform
T cells development and selection
Everything before thymus DOUBLE NEGETIVE (NO CD4 OR CD8) Cortex DOUBLE POSITIVE Medulla commit to CD4 or CD8 Postive and negative selection in Cortex -Positive: select those bind MHC ( done by epithelial cell) -Negative: remove bind to tight to self
Major histocompatibility complex (MHC)/ HLA HLA are on chromosome 6 CoDominant expression (mom and dads) - B2 microglobulin isn’t encoded with HLA but needed for function MHC II have INVARIANT CHAIN so MHC II don’t bind self MHC I MHC II HLA- A, B, C “ grade 1 ABC” HLA- DR, DP, DQ “ Dr DePide likes DQ” Alpha chain + B2 microglobulin Alpha + Beta “ alpha and beta present to T “alpha and beta” On all NUCLEATED On APC cell -not on RBC CD 8 + T cell CD 4+ Endogenous pathogen Exogenous pathogen the antigen degraded by proteasome phagocytosis of antigen tranposrt into ER by TAP phagosome+ lysosome fuse +
combine with MHC 1 in ER to golgi cell membrane
degrade antigen MHC II made in ER sent via vesicle to lysosome Lysosome degrade INVARIANT CHAIN, So antigen can bind
Acute Inflammation 1) cytokines increase selectins adhesion on endothelial cells 2) ROLLING : PMN bind E-Selectin on endothelial cells 3) ADHESION: the Integrin binds to ICAM on endothelial -LAD : if CD18 missing, part of integrin 4) pseudopods sent in and extravagation into tissue following chemokine gradient Chemokines for PMN : IL-8, C5a, LTB4
* APC picks up the antigen and then goes to the lymph node or spleen in order to activate T cells (B cells activate here too) nd
Antigen Presentation In 2 lymph tissue INTERACTIONS T cells bind to MHC on APC (the CD4 or CD8 stabilize it) CD3 send the intracellular signal CO-stimulatory signal : CD28 ( T) = B7 (APC) -without this causes ANERGY -CTLA-4/ CD152 compete with CD28 for B7 to turn off T cell - Superantigen : binds to the outside of TCR and causes it to join MHC II, leading to activation of MANY T CELLS HIGH CYTOKINE EXCESSIVE pro inflammation causing multiple organ failure
T cell types THo gets diff signals and transforms to diff cells ( CD4+) TH1 IL-12 from macrophage activate NK to secrete IFN-gamma= TH1 -Cell mediated response -marcophages (IFN-gamma) - CD8+ CTL ( IL-2) -makes IL-2, IFN-gamma, TNF-β -IFN-gamma inhibits TH2 TH2 IL4 causes TH2 to be made - Humoral response (antibodies) - Produces IL4,5,6,10,13,TGF- β -IL-10 and IL-4 inhibit TH1 Treg - Made when TGF-beta ( antinflammatory) - Make il-10 to turn off TH1 cells - CD25 surface marker, and FOXP3 transcription factor T17 - Made when TGF-beta + IL-6
- Pro-inflammation when makes IL-17 CD8+ T/ cytotoxic T cells : - Tumor cell, viral, transplanted tissue bc HLA don’t match
Clincial : Leprosy Mycobacterium leprae is intra macrophage pathogen therefore antibodies don’t work Tuberculoid: Th1 response good, forms granuloma to wall off infection + recover Lepromatous : TH2 response bad, antibodies don’t fix issue and further turn down TH1. HYPERgammaglobulinemia
Humoral Immunity
Need T cells for isotype switching -CD40 ligand (T) = CD40 B - W/o CD40 L= X-linked Hyper- IgM Syndrome
Papain - cut above hinge -3 fragments -2Fab + 1FC
Pepsin -cut below hinge - 2 fragments -1F(ab)2 + 1 FC -agglutinate + precipitate
The J chain keeps antibodies together ( IgM and IgA) IgM always first made even in allergic rxn ( 1 st exposure) IgA has secretory component that protected it form degradation in the lumen ADCC: Antiody dependant cell- mediated cytotoxicity -IgG for NK cells -IgE for Eosinophils in parasite infection
Compliment
Made in Liver C3a, 4a, 5a anaphylatoxins (bind to mast cell and basophil to degranulation) C5a chemotactic for PMN C3b Opsin MAC 5 9 * essential for Neisseria infection ( meningitis and gonorrhea ) Alternative (activated by pathogen) vs Classic IgM and IgG
Killing mechanisms Marcophage : nitrogen oxygen species and oxygen radicals CD8+ T cells 1. FAS ligand (T) = FAS on cell : tells cell to kill itself 2. Perforins form pore, release Granzymes into cell caspases activated 3. TNF – alpha and beta induce apoptosis NK cells: work with granzymes and perforin like CD8+ - Inhibited by MHC 1 * NK and CD8+ work at OPPOSITE TIMES -CD8 on when high MHC I -NK cells work when low MHC I ( inhibited by MHC I) - therefore when things turn down MHC I to escape, they are killed by NK
L-selectin (on lymphocytes) Il-1, Il-6, TNF alpha IL-10, TGF CD2 on T cells (ICAM) LFA-1 on T cell (integrin) CD28 ( T) CTLA-4 ( T)
- used to leave blood into 2nd lymphoid tissue via HEV ( high endothelial venules) Pro inflammatory Anti inflammatory Bind to LFA-3 on APC (integrin) Bind to ICAM-1 on APC Bind B7 on APC ( co-stimulatory signal) Bind B7 ( compete with CD28 to downregulate T cell)
Definitions:
Idiotype : variable region where antigen binds Isotype: the constant region of antibody that determines FUNCTION Epitope/ antigenic determinant : part of ANTIGEN that is recognized by receptor Avidity: increase with number binding site ( IgM highest pentamer, IgA 2 nd) Affinity: strength of binding ( IgG) Mitogen: activate clones of B or T cells -Poke weed : B cells
CLINICAL
Tdt used are a marker for ALL in B and T cells for early stage -Tdt adds random bases WIHTOUT TEMPLATE
Protein A from Staph bind to Fc of IgG, prevent phagocytosis bc the macrophage cant bind Mycobacteria, Leishmania, Listeria Facultative intracellular pathogens in macrophage therefore require TH1 response Adenovius vaccine = ONLY LIVE NOT ATTENUATED vaccine given cause intestinal IgA to be produced (hence all mucosal) therefore respiratory now protected CD21 receptor for EBV ( infect B cells) then T cells form downey cells MHC II deficiency / Bare lymphocyte syndrome II - mimic SCIDS and AIDS ( no CD4+ and low CD8+) -differentiate from SCIDS bc react to mitogens here ( can replicate but just low bc not activated) -IgM mostly since no CD4 TH2
Syndromes
Omenn Syndrome : missense mutation RAG causes decrease function (A.R.) B cells missing o o T cell decreased SCIDS: Rag 1 and 2 genes null mutation ( cant form chains) o A.R. No B or T cells o
Medbullets SCIDS (no proliferation with mitogen) X linked : IL-2 Receptor ( gamma chain) ( affect IL-2,4, 7) A.R.: Adenosine deaminase deficiency A.R. nonsense mutation Rag 1 and 2
* MHC II/ Bare lymphocyte mimic the SCIDS but proliferate with mitogen . Atopy: allergic rxns etc Burtons agammaglobinemia -Normal Pro B cell., the Pro cant go further Chronic Mucocutaneous Candidiasis Inability for T cells to produce cytokines to combat Candida Infection On skin, mouth, sometimes esophagus Infant have diaper dermatitis Need Fluconazole Auto recessive or spontaneous auto dominant
IL-12 deficiency: diminished TH1 response therefore mycobacteria attack
Catalase + infect Chronic Granulomatous Disease Staph aureus, Pseudomonas, E.coli, ASpergillus NTD test, if diseased (-) test , don’t turn blue LAD: CD18 on integrin LFA-1 ( beta chain)
HIV
Normal ratio 2:1 CD4 to CD8 In aids it reverses 1:2 CCR5 co receptor on the macrophage and dendritic cells -the macrophage and dendritic ARE NOT killed by HIV -act as reservoirs for the disease Immune evasion -Anitgenic drift of gp 120 -glycosylation of gp 120 ( like a mask) -Tat inhibit cytokine synthesis -Nef decrease MHC 1 Testing 1. ELISA: Antigen on plate, Add patients serum ( see if have Ig), then add ant- human IgG and colour change + 2. Westenr Blot ( confirmatory) : Antigen on nitrocellulose -Add patient serum ( antibodies) -Add anti- human Ig ( radiolabelled) * test for p24: capid -gp 160 : envelope protein -GP 120 : attatch -gp 41: fusion and entry
CHediak- Higashi Syndrome ( LYST gene mutation) : lysosomal storage protein PARTIAL ALBINISIM
Hypersensitivity Rxns 1. Early phase is degranulation : histamine, eosinophil chemoatractant, heparin Late phase rxn: Leukotriens and prostaglandins made Job’s Syndrome/ Hyper IgE Th1 don’t make enough IFN-gamma therefore PMN cant respond Absesses that are without inflammation “ cold” Retain primary teeth, eczema
Questions: U wooooorld
MHC1 works opposite from CD8+ T cells and NK Turn CD8 + T ON Turn NK OFF Therefore CD8 and NK don’t work at the same time any carpopedal spasm = HYPOCALCEMIA ( in child think missing parathyroid glands) Wiskott- Aldrich : Eczema, recurrent infection, thrombocytopenia -X-linked -B and T cell deficiency - WATER : W,A, thrombocytopenia purpura, eczema, recurrent infection
Lupus
ANA( anti nuclear antibodies) : sensitive, not specific Anti-ds DNA is specific LUPUS AntiSMith/ snRNP’s is specific LUPUS Anti-phopholipid antibody -cause (+) VDRL (False positive) AND prolonged PTT -venous and arterial thromboemobilisim leading to fetal loss Delayed hypersensitivity is from the Th1 CD4+ T cells PUS is caused by neutrophils - Attracted by IL-8, C5a, LT B4
Bradykinin
Leukotriene C4
-vasodilation + permeability -smooth muscle contraction - PAIN -vasoCONSTRICT + increase permeability -bronchospasm
Majority of myasthenia gravis patients have thymus abnormality ( thymoma, thymic hyperplasia): appear as anterior mediastinal mass (in front of the veins)
Guillain-Barre: CD 8+ T cells attack the endoneureium + cause demyelination PNS Polymyositis: symmetric proximal muscle weakness CD8+ mediated - increase CK creatnine kinase - increase anti-Jo1 antibodies
Eosinophilic Myositis: eosiniophils infiltrate skeletal muscle (rare) Sarcoidosis high CD4: CD8 ratio! (negative PPD even if they are + bc all the cells are sequestered at the lungs) Polymylagia rheumatic : bilateral stiffness in shoulder and pelvis. Fever, weightloss, increase ESR. ASSOCIATED WITH TEMPORAL ARTERITIS Transplants Hyper Acute: preformed antibodies. Occurs as soon as organ attached to vessels. Thrombosis ischemia and necrosis -Type 2 hypersensitivity reaction Acute: vasculitis of the vessel Chronic: fibrosis of graft and blood vessel have smooth muscle proliferation so obliterate Graft VS Host Bone marrow, liver transplant CD4 and 8 donor attack the recipient bc the MHC don’t match and recognized as forgein Organs affected most : skin (desquamation), liver (jaundice), GI (bleeding in poop)
HIV
Gp120 binds to both CD4 + CCR5 Without CCR5 cant enter the cell ( a chemokine receptor ) -homozygous mutant = no infection with HIV -heterozygous mutant = slow progression of disease CCR5 is on macrophages and dendritic cells ( reservoir) CxCR4 is on T cells Nef decrease expression MHC1 Tat increase viral replication Immunodeficiency X linked agammaglobinemia : Burton’s disease (only one where ONLY B CELLS ALL MISSING AND NOTHING ELSE) - tyrosine kinase not working - B cells stop differentiating at Pre B cell - Hypercellulairty in bone marrow with high PRE B CELL - No immunoglobulins C3 deficiency : no MAC then Neisseria infections ( meningitides and gonorrhea) ATM ( Ataxia Telengiectasis Mutated) -ATM gene -cause DNA double stand breaks -ataxia, teleangiectasis, and sinopulmonary infection (IgA deficiency) Chronic Granulomatous Disease: NADPH oxidase missing -infection with CATALASE POSITIVE ( staph, pseudomonas, enteric like E.coli, Klebsiella, Aspergillus)
- nitroblue tetrazolium test (-) if have it bc cant turn the test blue without reactive oxygen species - Catalase negative die bc the cells use H2O2 by myeloperoxidase to form HOCL (hypochlorite/ bleach). -Catalase + break down the H2O2 from its metabolisim. Hyper IgM: isotype switching now occurring ( alternative splicing) when the CD40 ligand on T cells is missing LAD Leukocyte adhesion deficiency: CD18 which is part of the integrin on leukocytes is missing. Cant ENTER TISSUE - HIGH WBC BLOOD - No puss in inflammation or abcess - Umbilical cord delayed separation - Poor wound healing - CD18 is beta chain of integrin - Bacterial infection, viral normal
Random Cadherin: Calcium dependent adheres btw cells T cells with CD4 and CD8 on them are IMMATURE CORTICAL T CELLS (in cortex of thymus (in medulla they have chosen either CD4 or 8 then) called DOUBLE POSITIVE Tetanus toxin retrograde transport to CNS and prevents release of GABA and glycine which are inhibitory transmitters - Tetanus toxoid causes antibodies against the toxin Thymic epithelial cells have role in POSITIVE SELECTION Express MHC and see if they bind o o If mind then + select If don’t bind then apoptosis o Eosinophils 1. Parasite : Antibody dependant Cytotoxicity : ADCC : IgE bind parasite and then bind eosinophil to relase its granules 2. Type 1 hypersensitivity: release histaminase, to decrease histamine from mast cell. Also LT to promote inflammation Eosinophils against ONLY HELMINTHS ( not giardia ) Give RHOGam 28 weeks gestation and immediate post partum so that the IgG will bind the Rh+ fetal cells before the mothers body can bind it and make antibodies against it Antiapoptosis Bcl-2 Bcl-x ( L for live) = prevent cytochrome c existing mitochondria via bax
Apoptosis Bak, Bax, Bim
CD15 = neutrophils and Reedsternburg cells in Hodgkins
IFN- alpha and beta cause synthesis antiviral proteins that degrade intracellular mRna and impair protein synthesis IL-10 and TGF- beta decrease inflammation
