Cellular Components Flashcards
Innate immunity COMPONENTS
Neutrophils, macrophages, monocytes, dendritic cells, natural killer (NK) cells (lymphoid origin), complement, physical epithelial barriers, secreted enzymes
Innate immunity MECHANISM
Germline encoded
Innate immunity RESISTANCE
Resistance persists through generations; does not change within an organism’s lifetime
Innate immunity RESPONSE TO PATHOGENS
Nonspecific
Occurs rapidly (minutes to hours)
No memory response
Innate immunity SECRETED PROTEINS
Lysozyme, complement, C-reactive protein (CRP), defensins
Innate immunity KEY FEATURES IN PATHOGEN RECOGNITION
Toll-like receptors (TLRs): pattern recognition receptors that recognize pathogen-associated molecular patterns (PAMPs) and lead to activation of NF-κB. Examples of PAMPs include LPS (gram ⊝ bacteria), flagellin (bacteria), nucleic acids (viruses).
Adaptive immunity COMPONENTS
T cells, B cells, circulating antibodies
Adaptive immunity MECHANISM
Variation through V(D)J recombination during lymphocyte development
Adaptive immunity RESISTANCE
Microbial resistance not heritable
Adaptive immunity RESPONSE TO PATHOGENS
Highly specific, refined over time
Develops over long periods; memory response is faster and more robust
Adaptive immunity SECRETED PROTEINS
Immunoglobulins
Adaptive immunity KEY FEATURES IN PATHOGEN RECOGNITION
Memory cells: activated B and T cells; subsequent exposure to a previously encountered antigen p stronger, quicker immune response
MHC I LOCI
HLA-A, HLA-B, HLA-C
MHC I loci have 1 letter
MHC I BINDING
TCR and CD8
MHC I STRUCTURE
1 long chain, 1 short chain
MHC I EXPRESSION
All nucleated cells, APCs, platelets
Not on RBCs
MHC I FUNCTION
Present endogenously synthesized antigens (eg, viral or cytosolic proteins) to CD8+ cytotoxic T cells
MHC I ANTIGEN LOADING
Antigen peptides loaded onto MHC I in RER after delivery via TAP (transporter associated with antigen processing)
MHC I ASSOCIATED PROTEINS
β2-microglobulin
MHC II LOCI
HLA-DP, HLA-DQ, HLA-DR
MHC II loci have 2 letters
MHC II BINDING
TCR and CD4
MHC II STRUCTURE
2 equal-length chains (2 α, 2 β)
MHC II EXPRESSION
APCs
MHC II FUNCTION
Present exogenously synthesized antigens (eg, bacterial proteins) to CD4+ helper T cells
MHC II ANTIGEN LOADING
Antigen loaded following release of invariant chain in an acidified endosome
MHC II ASSOCIATED PROTEINS
Invariant chain
A3 Disease
Hemochromatosis
B8 Disease
ADDISON disease,
MYasthenia gravis,
GRAVEs disease
(don’t Be late(8), dr. ADDISON, or else you’ll send MY patient to the GRAVE)
B27 Disease
Psoriatic arthritis,
Ankylosing spondylitis,
IBD-associated arthritis,
Reactive arthritis
(PAIR. Also known as seronegative arthropathies)
DQ2/DQ8 Disease
Celiac disease
I ate (8) too (2) much gluten at Dairy Queen
DR2 Disease
MULTIPLE sclerosis,
HAY fever,
SLE,
goodPASTURE syndrome
(MULTIPLE HAY PASTURES have DiRt)
DR3 Disease
diabetes mellitus type 1, SLE, graves disease, hashimoto thyroiditis, addison disease
(2-3, S-L-E)
DR4 Disease
RHEUMatoid arthritis,
diabetes mellitus type 1,
addison disease
(There are 4 walls in a “rheum” (room).)
DR5 Disease
Hashimoto thyroiditis
Hashimoto is an odd doctor (DR3, DR5).
Natural killer cells
Use perforin and granzymes to induce apoptosis of virally infected cells and tumor cells
enhanced by IL-2, IL-12, IFN-α, and IFN-β
B cells Major functions
Humoral immunity
Recognize antigen: undergo somatic hypermutation to optimize antigen specificity.
Produce antibody: differentiate into plasma cells to secrete specific immunoglobulins.
Maintain immunologic memory: memory B cells persist and accelerate future response to antigen
T cells Major functions
Cell-mediated immunity.
CD4+ T cells help B cells make antibodies and produce cytokines to recruit phagocytes and activate other leukocytes.
CD8+ T cells directly kill virus-infected cells.
Delayed cell-mediated hypersensitivity (type IV).
Acute and chronic cellular organ rejection
Positive selection
Thymic cortex. T cells expressing TCRs capable of binding self-MHC on cortical epithelial cells survive.
Negative selection
Thymic medulla. T cells expressing TCRs with high affinity for self antigens undergo apoptosis or become regulatory T cells. Tissue-restricted self-antigens are expressed in the thymus due to the action of autoimmune regulator (AIRE); deficiency leads to autoimmune polyendocrine syndrome-1
Macrophage lymphocyte interaction
Th1 cells secrete IFN-γ, which enhances the ability of monocytes and macrophages to kill microbes they ingest. This function is also enhanced by interaction of T cell CD40L with CD40 on macrophages
Cytotoxic T cells
Kill virus-infected, neoplastic, and donor graft cells by inducing apoptosis.
Release cytotoxic granules containing preformed proteins (eg, perforin, granzyme B).
Cytotoxic T cells have CD8, which binds to MHC I on virus-infected cells.
Regulatory T cells
Help maintain specific immune tolerance by suppressing CD4 and CD8 T-cell effector functions.
Identified by expression of CD3, CD4, CD25, and FOXP3.
Activated regulatory T cells (Tregs) produce anti-inflammatory cytokines (eg, IL-10, TGF-β).
IPEX (Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked) syndrome
genetic deficiency of FOXP3 pautoimmunity. Characterized by enteropathy, endocrinopathy, nail dystrophy, dermatitis, and/or other autoimmune dermatologic conditions. Associated with diabetes in male infants
