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immuno after mid
| Question | Answer |
|---|---|
| Radial Immunodiffusion | In the4se methods agar gel or similar gels are used on plates or petriplates. Both Ag and Ab diffuse freely in all directions. At some point a zone of equivalence will be formed whic is seen as percipitation |
| Nephelometry | Measures scattered light bouncing off antigen-antibody complexes |
| Agglutination: | When a particular Ag is mixed with its Ab i the presence of electrolytes at a suitable temperature and pH, the particles are clumped o agglutinated |
| slide agglutination: | rapid method to determine the presence of agglutinating antibodies |
| tube agglutination: | a standard method for quantitative estimation of Ab. The serum with Ab is diluted serially in several small test tubes to which a constant volume of Ag suspension is added. The tube showing highest agglutination is referred to as the titre |
| Fluoescnet Immunoassay | -Direct IF: tagged antibody added to unknown antigen fixed to slide -Indirect IF: patient + known fied antigen add tagged anti-antibody fluorescence |
| Fluorescein: | organic dye that is the most widely used label for IF procedures, absorbs blue light and emits an intense yellow-green fluorescence |
| Phycoerythrin | An efficient absorber of light ad a brilliant emitter of red fluorescence, stimulating its wide use as a label for IF |
| Complement dependent cytotoxicity | lymphocytes ae HLA-typed by crossmatching to panel reactive antibodies using the complement-dependent cytotoxicity test |
| ELISA: Enzyme Linked ImmunoSorbent Assay | Use of a ligand which is a molecule which can detect theAb and is covalently coupled to an enzyme such as peroxidase, betagalactosidase alkaline phosphatase etc |
| Indirect ELISA: | Used for detection of HIV Suspects serum is added and unbound proteins are washed off |
| Sandwich ELISA: | Used to detect the presence of Ag in a sample. The well is coated with Ab specific to the Ag and the suspect serum is added allowed to react |
| Competitive ELISA: | Antibody is first incubated in solution with a sample containing antigen |
| FLOW CYTOMETRY: | Fluorescence activated cell sorting (FACS) is a technology that allows simultaneous measurement of multiple physical and chemical characteristics of a single cell. |
| The Human Major Histocompatibility Complex (MHC)=(HLA) | 1. General organisation and inheritance of the MHC 1. MHC molecules and genes 1. Cellular distribution of MHC molecules 1. HLA Disease associations |
| MHC haplotypes: | Polymorphic (many alternative forms of the gene or alleles exist at each locus). Because of the close linkage the combination of alleles at each locus on a single chromosome is usually inherited as a unit. This unit is called a haplotype. |
| human leukocyte antigen (HLA) | system or complex is a gene complex encoding the major histocompatibility complex (MHC) proteins in humans.. |
| Class I MHC molecules | are present as transmembrane glycoproteins on the surface of all nucleated cells. Intact class I molecules consist of an alpha heavy chain bound to a beta-2 microglobulin molecule. |
| MHC class II | MHC class II molecules are a class of molecules normallyfound only on professional antigen-presenting cells These cells are important in initiating immune responses. |
| MHC class III region | encodes several molecules important in inflammation; Class III MHC molecules are souble proteins and exhibit much less polymorphism than Class I and Class II. |
| HLA and disease associations | 1. molecular mimicry 2. unbalanced binding among histocompatibility molecules and other MHC genes 3. HLA molecules - receptors for disease causing agents 4. Viral or bacterial antigens acts as superantigens 5. induced expression of class II HLA Ag |
| Passive immunisation: | involves transfer of preformed Abs and provides short-term protection without the requirement for an active I.R. |
| Active immunisation | induces clonal selection of lymphocytes and results in memory-cell formation. |
| How vaccines work: | • Induce active immunity • -Immunity and immunologic memory similar to natural infection but without risk of disease • Immunological memory allows • -Rapid recognition and response to infection • -Prevents or modifies effects of disease |
| Immune response to an ideal vaccine | Vaccine is taken up by antigen-presenting cells • activates both T and B cells to give memory cells • generates Th and Tc cells to the antigens • antigen persists to continue to recruit B memory cells and produce high affinity antibody |
| Attenuated microorganisms | - attenuated (weakened)vaccines undergo transient growth, they stimulate pronounced I.R. and memory-cell production; no booster required. |
| Inactivated (killed) microorganisms | s-repeated boosters required. |
| Purified macromolecules | s-less complex than whole organism, no unknown side effects. Using DNA techniques large quantities can be produced of a defined Ag for immunisation. |
| Live(attenuated) vaccines are used to protect against: | •Measles, mumps, rubella (MMR combined vaccine) •Rotavirus •Smallpox •Chickenpox •Yellow fever |
| Inactivated vaccines are used to protect against: | • Hepatitis A • Flu (shot only) • Polio (shot only) • Rabies |
| Subunit, recombinant, polysaccharide, and conjugate vaccines | These vaccines are used to protect against: • Hib (Haemophilus influenzae type b) disease • Hepatitis B • HPV (Human papillomavirus) • Whooping cough (part of the DTaP combined vaccine) • Pneumococcal disease • Meningococcal disease • Shingles |
| Toxoid vaccines | • Diphtheria • Tetanus |
| Protozoan/Parasitic infections | Both Humoral and cell-mediated I.Rs are involved. Humoral Ab is effective against blood-borne stages, but once protozoans infect host cells, cell-mediated immunity is necessary. |
| Organ specific Autoimmune Diseases | The response of the I.S. against self-components is termed autoimmunity. The mechanisms of self-tolerance protects a person from self-reactive lymphocytes that might lead to autoimmunity. |
| systemic autoimmune diseases | are directed against a broad spectrum of tissues in a variety of organs resulting from cell-mediated responses and cellular damage caused by autoAbs or immune complexes. |
| Cytokines | • Low molecular wt. proteins/peptides are important in cell signaling. • They mediate complex cellular interactions involving cells of the immune, inflammatory and hematopoietic systems. • They play imp. role in acute or chronic inflammatory responses. |
| The complement system | It consists of 30 serum and membrane proteins. After activation the various complement components interact to generate reaction products: se.Two pathways: i) The classical pathway and ii) The alternative pathway |
| The classical pathway | involves in order the C1,C4,C2 and C3 components, is initiated by binding of IgM and certain subclasses of IgG to soluble Ag or selfsurface Ags. |
| The alternative pathway | is most commonly initiated by surface constituents of microorganisms(bacteria, fungi,some viruses and some parasites) • However this pathway also can be initiated by IgG,IgA and IgE-Ag complexes |
| Leucocyte migration and Inflammation: | Lymphocytes undergo constant recirculation between the blood, lymph, lymphoid organs. This recirculation increases the chances of the small number of lymphocytes specific for a given Ag to actually encounter that Ag |
| Cell mediated and Humoral effector mechanisms | The final-stage mechanism, which is involved in parasite eradication or tissue damage by immune responses, is called the effector mechanism. A |
| General properties of effector T cells and activation requirements: | Naïve and effector T cells express different isoforms of CD45, designated CD45RA and CD45RO. The CD45RO isoform expressed on effector T cells associates better with CD4 and CD8 coreceptors than does the CD45RA isoform expressed by naïve T cells. |
| Hypersensitive reactions | are inflammatory reactions within the humoral or cell-mediated branches of the I.S. that lead to extensive tissue damage or even death. |
| Type I Hypersensitivity reaction | Exposure to an allergen activates B cells to form IgE-secreting plasma cells. The secreted IgE molecules bind to IgE-specific Fc receptors on mast cells and blood basophils. |
| Immunodeficiency | It is the absence or failure of normal function of one or more elements of the immune system. • Can be specific or non specific: • Specific = Abnormalities of B & T cells • Non specific = Abnormalities of non specific components |
| Congenital (primary) immunodeficiency | – genetic abnormality • defect in lymphocyte maturation |
| Acquired (secondary) immunodeficiency | – results from infections, nutritional deficiencies or treatments • AIDS, chronic leukemia |
| Chronic granulomatous disease (CGD) | In majority of patients with CGD, the deficiency is due to a defect in NADPH oxidase that participate in phagocytic respiratory burst. |
| X-linked Αgammaglobulinaemia* | ❖In X-LA early maturation of B cells fails ❖Affects males ❖Few or no B cells in blood ❖Very small lymph nodes and tonsils ❖No Ig ❖Small amount of Ig G in early age ❖Recurrent pyogenic infection |
| DiGeorge Syndrome | ❖It is the most understood T-cell immunodeficiency (Also known as congenital thymic aplasia/hypoplasia ) ❖Associated with hypoparathyroidism, congenital heart disease, fish shaped mouth. |
| SEVERE COMBINED IMMUNODEFICENCY(SCID) | The X-linked SCID is due to a defect in γ-chain of IL-2 also shared by IL-4, -7, -11 and 15, all involved in lymphocyte proliferation and/or differentiation. |
| Complement immunodeficiencies | • Associated with increased susceptibility to infection • Complement factors are necessary for opsonisation, bacterial killing and neutrophil chemotaxis. • many complement disorders are associated with increased susceptibility to autoimmune disease |
| AIDS - MAJOR IMMUNOLOGIC FEATURES: | CAUSED BY THE HUMAN IMMUNE DEFICIENCY VIRUS HIV-1 • LOW RESPONSE TO MITOGENS AND ANTIGENS • ELEVATED IMMUNOGLOBULIN LEVELS • REDUCED / ABSENT AB RESPONSE AFTER IMMUNISATION • INCREASED CIRCULATING IMMUNE COMPLEXES |
| HIV | is an enveloped retrovirus containing ssRNA that is the causative agent for AIDS. • HIV infection leads to numerous immunologic abnormalities and eventually severe depletion of CD4+ T cells. • Both Humoral and Cell-mediated immunity is depressed |
| Autograft | Self-tissue transferred from one site to another(eg patients with burns) |
| Isograft | Tissue transferred between genetically identical(monozygotic) twins |
| Allograft | Organ grafts from one person to another Xenograft: Tissue transferred between different species |
| Cell Transplant: | eg haematopoietic stem cell transplants |
| Transplantation Antigens: | Tissues that are antigenically similar are called histocompatible. |
| Direct Allorecognition: | recipient T cells(CD8) bind and respond directly to foreign HLA proteins on graft cells |
| Indirect Allorecognition: | foreign MHC Ags are presented by phagocytic cells and CD4 cells respond Presentation of HLA proteins by recipient APC to recipient |
| Graft rejection process | 1)Sensitisation stage and 2)Effector stage. |
| Hyperacute rejection: | It occurs within minutes to hours after the vascular supply to the transplanted organ is established The result is ischemia and necrosis of the transplanted tissue. |
| Acute cellular rejection: | -days to weeks after transplantation. CD8 cells mediate cytotoxic reactions to foreign MHC-expressing cells, while CD4 cells produce cytokines and induce delayed type hypersensitivity reactions |
| Chronic rejection: | results from a process of graft arteriosclerosis. Characterised by fibrosis and scarring leading to cold ischaemia,acute rejection episodes and toxicity from immunosuppressive drugs. |
| Effector stage | Leukocytes(APCs) derived from the donor graft migrate to the regional lymph nodes of the recipient resulting in the activation of TH cells in response to different class II MHC Ags expressed by the donor’s APCs |
| TISSUE TYPING: | By microcytotoxicity test. White cells from potential donors and the recipient are added to separate wells of a microtiter plate that contain Abs to specific Class I and Class II MHC molecules. |
| Clinical Transplantation: | Organ Transplantation-Scientific research had an impact on the success rates for organ transplantation. In the case of Kidney transplants the rate has reached 95%. |
| BONE MARROW TRANSPLANTATION: | A therapy for a number of malignant haematological diseases including leukaemia,lymphoma, aplastic anaemia, thalassaemia major and immunodeficiency diseases. |
| GRAFT VERSUS HOST DISEASE(GVHD): |
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