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58 Cards in this Set
- Front
- Back
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What are the main components of innate immunity?
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Epithelial barriers
phagocytic cells NK cells plasma proteins (complement) Toll like receptors |
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What are toll like receptors?
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membrane proteins that recognize a variety of microbe-derived products present on phagocytes. They stimulate immune response against microbes
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What is adaptive immunity? What does it consist of?
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Acquired immunity - consists of mechanisms stimulated by microbes and capable of recognizing non-microbial substances called antigens
Consists of lymphocytes and their products |
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What are the 2 types of adaptive immunity?
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1. Cell mediated immunity against intracellular microbes mediated by T lymphs
2. Humoral immunity protects against extracellular microbes and their toxins mediated by B lymphs |
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How do T cells recognize cell bound antigen?
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TCR (T-cell receptor) <-- first signal
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What is the usefulness of TCR gene rearrangements?
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useful in classifying lymphoid malignancies - each T cell has unique TCR - can distinguish polyclonal (non-neoplastic) from monoclonal (neoplastic) T cell proliferations
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What do CD4 do and what class of MHC to they bind?
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T helper cells secrete cytokines which influence other cells and bind Class II MHC
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What do CD8 do and what class of MHC to they bind?
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CTLs (cytotoxic t cells) kill virus infected or tumor cells by direct cytotoxicity and bind Class I MHC
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What do B cells develop into after exposure to antigen and what do they secrete?
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They form plasma cells and secrete immunoglobulins (antibodies)
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What is the antigen binding component on B cells?
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IgM (or IgD) on surface of B cell are antigen binding component of receptor complex
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What is the antigen binding component on B cells?
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IgM (or IgD) on surface of B cell are antigen binding component of receptor complex
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What is the usefulness of rearranged immunoglobulin genes on B cells?
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Each B cell receptor has unique antigen specificity - presence of rearranged immunoglobulin genes in a lymphoid cell used as a molecular marker of B-lineage
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What is the usefulness of rearranged immunoglobulin genes on B cells?
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Each B cell receptor has unique antigen specificity - presence of rearranged immunoglobulin genes in a lymphoid cell used as a molecular marker of B-lineage
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What are the 2 types of dendritic cells?
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Interdigitating dendritic cells
follicular dendritic cells |
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How do interdigitating dendritic cells function?
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most important antigen presenting cell* for initiating primary immune repsonses against protein antigens
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How do follicular dendritic cells function?
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Have Fc receptor for IgG, trap antigen bound to antibody
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What innate ability to NK cells have?
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can lyse tumor cells, virally infected and some normal w/o previous sensitization
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What are the two NK cell markers?
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CD16 and CD56
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How does CD16 function?
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CD 16 is the Fc receptor for IgG - and allows NK cell to lyse IgG coated target cells
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What is ADCC?
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Ab dependent cell mediated cytotoxicity (ADCC)
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What 2 receptors regulate NK cells?
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1. one activates killing by recognizing some molecule on target membrane
2. one binds to self Class I MHC molecules and inhibits lysis (prevents lysis of normal cells, virally infected cells or transformed neoplastic cells don't have normal Class I molecules) |
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What do NK cells secrete?
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cytokines
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What is the main function of MHC molecules?
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to bind peptide fragments of foreign proteins for presentation to antigen-specific T cells
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What chromosome are MHC molecule genes found on?
What is the gene cluster called? |
6
Major histocompatibility complex - MHC or HLA |
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What are the 3 categories of the HLA system?
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Class I: HLA-A, B, C
Class II: HLA-D -- DP, DQ, DR Class II: complement |
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What is Type I hypersensitivity?
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immediate hypersensitivity
Rapidly evolving immune reaction occurring within minutes of combination of antigen with IgE antibody bound to surface of mast cells in a sensitized host. It can manifest systemically or locally |
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What is Type II hypersensitivity?
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Antibody Mediated
Antibodies are formed against target antigens on molecules intrinsic to cell membranes or ECM |
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What is Type III hypersensitivity?
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immune complex mediated
Mediated by antigen-Ab (immune) complexes which initiate inflammatory reaction at sites of deposition |
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What is Type IV hypersensivity?
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T-cell mediated
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What are the 2 phases of local reaction of a Type I hypersensitivity?
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Early: response due to vasoactive amines, lipid mediators
Late: due to cytokines |
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What are the major cells involved in Type I hypersensitivity?
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Neutrophils
Eosinophils Th2 lymphocytes |
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What type of infections is Type I useful?
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helminthic infections
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What are the 3 different antibody dependent mechanisms of a Type II hypersensitivity?
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Opsonization and phagocytosis
Inflammation Antibody mediated celluar dysfunction |
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What are the 4 clinical situations in which opsonization and phagocytosis occur?
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1. transfusion reactions
2. erythroblastosis fetalis 3. autoimmune hemolytic anemia, agranulocytosis, thrombocytopenia 4. certain drug reactions |
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What 2 diseases are examples of antibody-mediated cellular dysfunction?
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Myasthenia gravis and Pemphigus vulgaris
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What 2 types of antigens can cause immune complex mediated injury?
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Exogenous: foreign protein, bacterium, virus
Endogenous: patient produces ab against self-components |
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What are the 2 patterns of injury seen with Type III?
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Generalized: immune complexes formed in circulation
Localized: to particular organs |
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Describe the 3 phases of the systemic form of Type III hypersensitivity.
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1. immune complex formation
2. immune complex deposition 3. inflammatory reaction at various sites throughout the body |
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What is the major morphologic feature of immune complex injury?
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Acute necrotizing vasculitis
- vessel wall shows fibrinoid necrosis |
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What are the 2 types of reactions in type IV hypersensitivity?
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Delayed-type hypersensitivity (DTH) - CD4 cells
Direct cell cytotoxicity - CD8 cells |
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What is the classic example of delayed type hypersensitivity?
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Mantoux reaction (tuberculin test) elicited in individual already sensitized to tubercle bacillus by previous infection
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What 2 types of hypersensitivity reactions occur in transplant rejection?
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Cell-mediated (Type IV) and antibody-mediated (Type II) hypersensitivity reactions against MHC molecules on the foreign graft
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What 2 pathways are there for the T cell mediated reactions in rejection?
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Destruction of graft cells by CD8+ CTLs
Delayed type hypersensitivity reactions triggered by activated CD4+ Th cells |
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What are the 2 forms of humoral rejection?
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antibody mediated rejection
hyperacute rejection (multiparous women) |
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How does humoral rejection manifest morphologically?
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Cyanotic, mottled, flaccid organ
Widespread damage to vessels |
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What are 2 ways to increase graft survival?
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HLA matching and immunosuppression
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What risks are involved with immunosuppressive therapy?
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vulnerability to fungal, viral, bacterial infections and EBV induced lymphoid tumors
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What are the 3 major complications of transplanting allogenic hematopoetic cells?
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Transplant rejection
Graft-vs-host disease Immune deficiencies |
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When does graft-vs-host occur?
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acute - within days to weeks after transplant
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What is the mechanism of acute Graft-vs-Host disease?
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immunocompetent cells are transplanted into immunocompromised recipient
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What are the 3 organ systems affected and what are the clinical manifestations of graft-vs-host disease?
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Liver, Skin, Gut
Jaundice, Generalized rash, Bloody Diarrhea (yellow patient, red rash, diarrhea) |
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What is central self-tolerance?
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clonal deletion and clonal anergy
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What are the 2 roles of infection in autoimmunity?
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Induction of costimulators on APCs
Molecular mimicry |
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What is ANA?
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Antinuclear antibodies
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What 2 specific ANA's are diagnostic of SLE?
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Anti-Sm (smith)
Anti-double-stranded DNA |
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What are 2 other autoantibodies associated with SLE?
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Abs found against RBCs, platelets, lymphocytes (Type II HS)
Antiphopholipids in 30% to 40% of patients |
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What 2 types of hypersensitivities occur in SLE?
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Type II and III
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Which hypersensitivity mechanism explains the hematologic findings in SLE?
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Type II - damaged nuclei lose chromatin pattern and become homogenous - LE body
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