Immunology Flashcards
What is produced in bone marrow?
immune cell production
B cell maturation
What is produced in thymus?
T cell maturation
Lymph node anatomy
capsule: subcapsular sinuses, trabeculae of connective tissue, trabecular sinuses
outer cortex: nodules, follicles of b cells, germinal center where B cells differentiate
inner cortex (paracortex): no nodules, T cells, high endothelial venules, eosinophilic
Medulla: cords of lymphoid tissue and medullary sinuses
encapsulated, bean shaped structures, dendritic cells, plasma cells
Deep cervical lymph nodes
Drain: head, neck, oropharynx
path: Kawasaki dz
Supraclavicular lymph nodes
R: L Virchow node
L: abdomen, pelvis
path: cancer of thorax, abdomen, pelvis
Epitrochlear lymph node
Drain: hand, forearm
path: secondary syphilis
Spleen anatomy
LUQ of abdomen, anterolateral to L kidney
Periarteriolar lymphatic sheath: T cells
Follicle: B cells
Marginal zone: macrophages, specialized b cells, antigen-presenting cells
White pulp: antibody coated bacteria are filtered our and antibodies are made by B cells, filters blood
Red pulp: old RBC destroyed
Thymus anatomy, embryo, location, function
anterosuperior mediastinum
Thymus: endoderm
Thymic lymphocytes: mesoderm
cortex: immature T cells
Medulla: mature T cells
Hassall corpuscles: containing epithelial reticular cells
F: t cell differentiation and maturation
Innate immunity
Neutrophils, macrophages, monocytes, dendritic cells, NK cells, complement, physical epithelial barriers
Germline encoded, nonspecific, rapid, no memory
Protein secretion: lysozyme, complement, C-reactive protein, defensisns, cytokines
Pathogen recognition: toll-like receptors, pattern recognition receptors
Adaptive immunity (Protein secretion, Pathogen recognition, cells included, and what is it)
T, B cells, and circulating antibodies
variation through V(D)J recombination during lymphocyte development, high specific, memory, longer response
Protein secretion: immunoglobulin, cytokines
Pathogen recognition: memory cells
MHC 1
Loci: HLA-A, HLA-B, HLA-C
binding TCR and CD8
1 long and 1 short
F: Present endogenous antigens (viral or cytosolic proteins) to CD8+ cytotoxic T cells
Expression: All nucleated cells, APCs, platelets (except RBCs)
Antigen loading: Antigen peptides loaded onto MHC I in RER after delivery via TAP (transporter associated with antigen processing)
Associated proteins: B2-microglobulin
Path: B27 PAIR psoriatic arthritis, ankylosing spondylitis, IBD-arthritis, reactive arthritis
MHC II
Loci: HLA-DP, HLA-DQ, HLA-DR
TCR and CD4
2 equal length chains
Expression: APCs\Function: Present exogenous antigens (bacterial proteins) to CD4 helper T cells
Antigen loading: Antigen loaded following release of invariant chain in acidified endosome
path: DQ2/8 (celiac), DR3 (DM I, SLE, graves, Hashimoto, Addison disease), DR4 (RA, DM I, Addison disease)
Natural Killer (NK) cells
innate immune system
A: perforin and granzymes to induce apoptosis of virally infx and tumor cells and antibody-dependent cell-mediated cytotoxicity
Stim: induced to kill when exposed to nonspecific activation signal on target cell, or absence of inhibitory signal on target cell surface or CD16 binds Fc region of bound IgG
Inc activity: IL-2, IL-12, IFN-a, IFN-B
B cell
Action: recognize and present antigen, produce antibodies, and maintain immunologic memory
T cells
CD4: help B cells make Ab and produce cytokines to recruit phagocytes and activate other leukocytes
CD8: directly kill virus-infx and tumor cells
MCH II x CD4 = 8
MCH I x CD8= 8
Type 1 hypersensitivity
Immediate: Antigen crosslinks IgE on pre-sensitized mast cells -> degranulation -> histamine (runny everything), tryptase, and leukotriene release (anaphylactic)
Late: chemokines attract inflammatory cells -> inflammation and tissue damage
Type II hypersentivity mechanism and example
Antibody binds to cell-surface of antigen -> opsonize -> activate phagocytosis, complement, NK cell killing-> abnormal blockage or activation of downstream effects, destruction
path: autoimmune hemolytic anemia, immune thrombocytopenia, transfusion rxn, hemolytic dz of the newborn, Goodpasture syndrome, Rheumatic fever, transplant rejection, myasthenia gravis, graves dz, pemphigus vulgaris
Type III hypersentivity mechanism and example
Antigen-Antibody-Complement (IgG) creates complex -> deposits somewhere-> attracts neutrophils and release lysosomal enzymes -> causing localized damage where it has deposited
path: SLE, RA, reactive arthritis, polyarteritis nodosa, poststreptococcal glomerulonephritis, IgA vasculitis, vaccine booster
Type IV hypersentivity
direct cell cytotoxicity via CD8 T cells kill targeted cells
effector CD4 T cells recognize Ag and release inflammation-inducing cytokines -> macrophage
Path: contact dermatitis, graft vs host dz
Helper T Cell Th1
Reg
(+) IFN-y, IL-12
(-) IL-4, IL-10
Release: IFN-y, IL-2
Action: activate macrophages, cytotoxic T cells, infection
Helper T Cell Th2
Reg: (+) IL-2, IL-4 (-) IFN-y
Release: IL-4, 5, 6, 10, 13
Action: activate eosinophils, IgE, Parasitic, allergic
Helper T Cell Th17
Reg: (+) TGF-B, IL-1, IL-6 (-) IFN-y, IL-4
Release: IL-17, 21, 22
Action: induce neutrophil inflammation
Helper T Cell Treg
Reg: (+) TGF-B, IL-2 (-) IL-6
Release: TGF-B, IL-10, 35
ACtion: prevent autoimmunity
Antigen structure and function
Fab: determines type of ag that binds
Fc: antibody class switching
Cytotoxic T cells
kill virus-infected, neoplastic, and graft cells via apoptosis, release cytotoxic granules containing preformed proteins
T cell activation
Antigen presenting cell ingests and processes Ag -> migrates to draining lymph node -> exogenous ag presents on MHC II and recognized by T-cell receptor on CD4 cell-> co-stimulatory signal via interaction of protein on dendritic cell and naïve T cell -> activated Th cell produces cytokines
IgG
most abundant in serum
fixes complement, opsonizes bacteria, neutralizes bacterial toxins and viruses
crosses placenta
IgA
mucous membrane, breast milk, crosses epithelial cells
does not fix complement
produced in peyer patches
most produced but not in serum
IgE
binds mast cells and basophils
Type I hypersentivity
contribute to immunity to parasites by activating eosinophils
IgM
primary response to an ag
fixes complement
multiple binding site
Complement
Activation: IgG or IgM, microbe surface molecules, lectin
Opsonin’s: C3b
Anaphylaxis: C3a, C4a, C5a
Neutrophil chemotaxis: C5a
MAC: C5b-9 neutralizing Neisseria species
Respiratory Burst
ROS to kill bacteria and foreign invaders -> activates catalase/glutathione peroxidase - glutathione reductase -> glucose-6-phosphatse dehydrogenase
catalase (+) organism can neutralize H2O2
Live attenuated Vaccine
can revert to virulent form, retain capacity of transient growth w/in host
induce cellular and humoral response, strong, lifelong
ex: MMR, typhoid
Killed/Inactivated
Antibody to surface antigen
pathogen is inactivated by heat or chemicals
Ex: Influenza
Subunit, recombinant, polysaccharide, conjugate
target specific epitopes of antigen
less adverse reactions
weaker immune response and costly
Toxoid vaccine
denatured bacterial toxin w/ intact receptor binding site
stimulates immune Ab response w/ ability to cause disease
protects against bacterial toxins
antitoxin levels decrease over time, needs booster shots
ex: clostridium tetani
mRNA vaccine
lipid nanoparticle delivers mRNA
induce cellular and humoral response, side effects (myocarditis, pericarditis)
safe in pregnancy
EX: covid
X-linked agammaglobulinemia def
Defect in BTK, a tyrosine kinase gene
No B-cell maturation
X-linked agammaglobulinemia cause
genetics
X-linked agammaglobulinemia path
mutation in Burton’s Tyrosine Kinase gene on x chromosome -> ineffective BTK enzyme-> B-lymphocyte precursors fail to mature into B lymphocytes, plasma cells -> differentiation stops at pre-B cell stage -> absence of B-cells in circulation -> deficiencies of all Ig -> higher risk of developing infections
X-linked agammaglobulinemia RF
Males, 6-18 mon, FH,
X-linked agammaglobulinemia comp
live vaccines autoimmune diseases, skin infections, lymphoma
X-linked agammaglobulinemia clinical
Recurrent bacterial and enteroviral infections after 6 months (decreased maternal IgG)
Absent B cells in peripheral blood
Decreased IgG
Absent/scanty lymph nodes and tonsils
Selective IgA deficiency def
isolated deficiency of IgA
Selective IgA deficiency cause
idiopathic
Selective IgA deficiency path
IgA deficiency
Selective IgA deficiency RF
FH
Selective IgA deficiency comp
Higher risk for giardiasis
Can cause false-positive B-hCG test
Selective IgA deficiency clinical
asymptomatic
Common Variable Immunodeficiency def
defect in B-cell differentiation
Common Variable Immunodeficiency cause
idiopathic, mutations BAFF or ICOS
Common Variable Immunodeficiency path
Decreased plasma cells and immunoglobulins
Common Variable Immunodeficiency RF
FH
Common Variable Immunodeficiency comp
Increased risk for AI disease, bronchiectasis, lymphoma, sinopulmonary infections, granulomatous infiltration
Common Variable Immunodeficiency clinical
recurrent infections
Chronic Mucocutaneous Candidiasis def
T-cell dysfunction
Chronic Mucocutaneous Candidiasis clinical
persistent and noninvasive Candida labicans infx of skin and mucous membrane
Severe Combined Immunodeficiency def
combined defects in T, B lymphocyte development, function
Severe Combined Immunodeficiency cause
SCID, cytokine receptor defects, adenosine deaminase deficiency, mutation y-chain subunit of IL receptors, RAG mutation
Severe Combined Immunodeficiency path
X-linked recessive
combined defects in T,B lymphocytes development or function
Severe Combined Immunodeficiency RF
male
Severe Combined Immunodeficiency clinical
recurrent infx, oral candidiasis (thrush), chronic diarrhea, failure the thrive, morbilliform rash
Spleen function
Filtration
Iron metabolism
Prevention of infection
Red blood cell and platelet storage
Bone marrow function
Immune cell production (origin of stem cells)
Production of cytokines in BM serves as necessary signals to B cells to differentiate by up-regulating B cell markers
B cell maturation
Bone marrow Microscopic Anatomy
red: hematopoietic island widely distributed throughout loose connective tissue network, large thin walled sinusoids, granulocytes, monocytes, megakaryocytes, lymphocytes,
yellow: connective tissue, adipocytes, dormant hematopoietic clusters,
reticulin: type III collagen, macrophages,
Bone marrow embryo
mesodermal cells in yolk sac
Tonsils Microscopic Anatomy
stratified squamous epithelium
antigen presenting cells
lymphoid follicles surrounded by connective tissue w/ tonsillar crypts
center contains lymphocytes
Tonsils Function
Filtration of macrophages, circulation of B and T cells, immune response activation
Waldeyer ring consists of lingual, palatine, pharyngeal, and tubal tonsils
Palatine tonsil
between the palatoglossal arch anteriorly and the palatopharyngeal arch posteriorly
stratified squamous epithelium w/ 15-20 crypts
lymphocytes, bacteria and desquamated epithelial cells
Lingual tonsil
small round elevations that sit on the most posterior part of the tongue base
stratified squamous epithelium one crypt
Tubal tonsils
posterior to the opening of the Eustachian tube (the torus tubaris) in the nasopharynx.
Pharyngeal tonsil
nasopharynx
attached to periosteum of sphenoid bone
ciliated pseudostratified columnar epithelium, goblet cells
Lymph node function
Place where T and B cells hang out
ECF excess with antigens percolates through LNs and memory T and B cells can activate against any antigen previously seem
Mediastinal Lymph node
trachea, esophagus
path: lung CA, TB, sarcoidosis, granulomatous dz
Submandibular, submental LN
D: oral cavity, ant. tongue, lower lip
P: oral cavity cancer
Hilar LN
D: lungs
P: lung CA, TB, sarcoidosis, granulomatous dz
Axillary LN
D: upper limb, breast, skin above umbilics
P: mastitis, breast ca
Periumbilical LN
D: abdomen, pelvis
P: gastric ca
Celiac LN
D: liver, stomach, spleen, pancreas, upper duodenum
p: mesenteric lymphadenitis, IBD, celiac dz
Superior mesenteric LN
lower duodenum, jejunum, ileum, colon (splenic flexure)
p: mesenteric lymphadenitis, IBD, celiac dz
Inferior mesenteric LN
colon (splenic flexure to upper rectum)
mesenteric lymphadenitis, IBD, celiac dz
Para-aortic LN
testes, ovaries, kidneys, fallopian tubes, uterus
metastasis
External iliac LN
cervix, vagina (upper third), superior bladder, body of uterus
STI, medial foot/leg cellulitis
Internal iliac LN
lower rectum to anal canal, bladder, middle 1/3 vagina, cervix, prostate
STI, medial foot/leg cellulitis
Superficial inguinal LN
anal canal, skin below umbilicus, scrotum, vulva, vagina lower 1/3
STI, medial foot/leg cellulitis
Popliteal LN
dorsolateral foot, posterior calf
lateral foot/leg cellulitis
Interferon-gamma
Th1, secreted by NK cells and T cells in response to Ag or Il-12 from macrophages, stimulates macrophages to kill phagocytosed pathogens, inhibits differentiation of Th2, induces IgG class switch
IL-4
induces differentiation of T cells into Th2 cells, promotes growth of B cells, enhances class switching to IgE and IgG
IL-5
promotes growth and differentiation of b cells, enhances class switching to IgA, stimulates growth and differentiation of eosinophils, Th2
IL-10
TGF-B and IL-10 both attenuate the immune response, decreases expression of MHC class II and Th1 cytokines, inhabits activated macrophages and dendritic cells, secreted by reg T cells, Th2
IL-13
promotes IgE production by B cells, induces alternative macrophage activation, Th2
INF y
secreted by NK cells and T cells in response to antigen or IL-12 from macrophages, stimulates macrophages to kill pathogens; inhibit differentiation of Th2 cells, induces IgG
HLA A3
Hemochromatosis
HLA B8
Addison disease, Myasthenia gravis, Graves
Don’t Be late(8), Dr. Addison, or else you’ll send my patient to the grave
HLA B27
Psoriatic arthritis, Ankylosing spondylitis, IBD-associated arthritis, Reactive arthritis
PAIR
HLA C
Psoriasis
DQ2/DQ8
Celiac disease I ate(8) (2) much gluten at Dairy Queen
DR2
Multiple sclerosis, hay fever, SLE, Goodpasture syndrome
DR3
Rheumatoid arthritis, DM1, Addison disease
DR5
Hashimoto thyroiditis
Hashimoto is an odd Dr (DR3, DR5)
IL-1
acute inflammation, (Macrophages and Monocytes) Fever, T-cell prolif
IL-2
(CD4 cells) Stimulates T cells, NK cells, CD4 and CD8
IL-3
Stimulates bone marrow
IL-6
Stimulates acute phase protein production and fever
IL-11
(Fibroblast) Megakaryocyte potentiator, stimulates IgG
TNF-alpha
activates endothelium, WCB recruitment, vascular leak
IL-8
chemotactic factor for neutrophils
IL-12
differentiation of T cell into Th1 cells, activate NK cells
INF-a
leukocytes) Inhibits tumor proliferation, enhances NK growth
INF-B
(fibroblasts)
Response to foreign body
albumin and fibrinogen attach to surface -> over time small proteins get replaced w/ larger proteins -> neutrophils migrate to area and adhere to protein layer -> release ROS and proteolytic enzymes -> increase vascular permeability -> monocytes turn into macrophages -> proliferation and recruitment and replace neutrophils -> release TNF alpha, IL-1b, IL-6, and IL-8 -> macrophage cover exposed surface of implant via integrins -> macrophage undergo cytoskeletal remodeling they flatten over the surface of the implant in an attempt to engulf and phagocytose it -> continue to recruit macrophages -> release degrading enzymes and ROS to break down implant -> break it down -> stops -> if don’t break down -> encapsulation of implant w/ fibrous tissue
Structure of Complement
plasma proteins
C1: C1s, C1r, 6C1q bind to Fc portion of antibody, require Ca
Function of Complement
destroy gram negative bacteria
C3b - Opsonization, allow for phagocytosis (C3b binds to lipopolysaccharides on bacteria)
C3a, C4a, C5a - Anaphylaxis, mast cells and basophils
C5a and C3a - Neutrophil, eosinophils, monocytes, and macrophage chemotaxis
C5b-9 (MAC) - Cytolysis, kills infected cells or pathogen
Pathway of Classic Complement
2 or more C1q bind to antibodies bound to antigen -> C1 twists exposes C1r and C1s allowing C1r to cleave C1s -> C1 cleaves C4 into C4b and C4a -> C4b binds to surface of pathogen -> C1 cleaves C2 into C2a and C2b -> C2b bind to C4b on pathogen -> C3 convertase cleaves tons of C3 into C3b and C3a -> C3b binds to C3 convertase turning it into a C5 convertase (C4b2b3b) -> cleaves C5 into C5a and C5b-> C5b binds to C6, C7, C8 bind to cell membrane and penetrate through it -> multiple C9 join and create a channel straight through pathogen membrane
Lectin binding pathway
mannose binding lectin protein binds to mannose on cell surface -> cleaves C4 and C2 -> C3 convertase -> C3 convertase cleaves tons of C3 into C3b and C3a -> C3b binds to C3 convertase turning it into a C5 convertase (C4b2b3b) -> cleaves C5 into C5a and C5b-> C5b binds to C6, C7, C8 bind to cell membrane and penetrate through it -> multiple C9 join and create a channel straight through pathogen membrane
Alternative Complement Pathway
at slow rate of cleavage of C3 into C3b and C3a-> C3b binds to cell membrane -> factor B will bind to C3b and that will allow factor B to be cleaved by factor D into Bb and Ba -> Bb will stay bound to C3b -> acts as a C3 convertase -> C3b binds to C3 convertase turning it into a C5 convertase (C4b2b3b) -> cleaves C5 into C5a and C5b-> C5b binds to C6, C7, C8 bind to cell membrane and penetrate through it -> multiple C9 join and create a channel straight through pathogen membrane
C1 inhibitor and factor I stops this