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Tumor immunology
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Tumor antigens Tumor – specific antigens (TSA)
complexes of MHCgp I with abnormal fragments of cellular proteins (chemically induced tumors, leukemia with chromosomal translocation) complexes of MHC gp with fragments of oncogenic viruses proteins (tumors caused by viruses: EBV, SV40, polyomavirus…) abnormal forms of glycoproteins (sialylation of surface proteins of tumor cells) idiotypes of myeloma and lymphoma (clonotyping TCR and BCR)
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Tumor antigens b) Tumor - associated antigens (TAA)
present also on normal cells differences in quantity, time and local expression auxiliary diagnostic markers
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Tumor - associated antigens (TAA)
onkofetal antigens -on normal embryonic cells and some tumor cells -fetoprotein (AFP) - hepatom carcinoembryonic antigen (CEA) - colon cancer melanoma antigens - MAGE-1, Melan-A
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Tumor - associated antigens (TAA)
antigen HER2/neu eceptor for epithelial growth factor, mammary carcinoma EPCAM – epithelial cell adhesion molecule, metastases differentiation antigens of leukemic cells - present on normal cells of leukocytes linage CALLA -acute lymphoblastic leukemia (CD10 pre-B cells)
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Immune surveillance of tumors
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Anti-tumor immune mechanisms
If tumor cells are detected, in defense may be involved non-specific mechanisms (neutrophilic granulocytes, macrophages, NK cells, complement) and antigen-specific mechanisms (TH1 and TC cells, antibodies).
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Anti – tumor defense tumor cells are weakly immunogenic
regulatory T cells promote progression of cancer occurs when tumor antigens are presented to T cells by dendritic cells activated in the inflammatory environment
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Anti – tumor defense DC are necessary for activation of antigen specific mechanisms predominance of TH1 (IFN , TNF) specific cell-mediated cytotoxic reactivity – TC activation of TH2 → stimulation of B cells→ tumor specific antibodies production (involved in the ADCC) tumor cells are destroyed by cytotoxic NK cells (ADCC) interferons - antiproliferative, cytotoxic effect on tumor cells INF - DC maturation
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Mechanisms of tumor resistance to the immune system
high variability of tumor cells low expression of tumor antigens sialylation some anticancer substances have a stimulating effect production of factors inactivating T lymphocytes expression of FasL → T lymphocyte apoptosis inhibition of the function or durability dendritic cells (NO, IL-10, TGF-)
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Transplantation 11
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Transplantation = transfer of tissue or organ
autologous - donor = recipient syngeneic - genetically identical donor and recipient (identical twins) allogeneic - genetically nonidentical donor of the same species xenogenic - the donor of another species implant - artificial tissue compensation 12
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Allotransplantation differences in donor-recipient MHC gp and secondary histocompatibility Ag alloreactivity of T lymphocytes - the risk of rejection and graft-versus-host disease 13
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Tests prior to transplantation
ABO compatibility (matching blood group) -risk of hyperacute or accelerated rejection (= formation of Ab against A or B Ag on graft vascular endothelium) HLA typing (matching tissue type) - determining of HLA alelic forms by phenotyping or genotyping Cross-match - detection of preformed alloantibodies (after blood transfusions, transplantation, repeated childbirth) Mixed lymphocyte reaction - testing of T lymphocytes alloreactivity 14
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HLA typing 1) Serotyping (microlymfocytotoxic test)
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HLA typing 2) Molecular genetic methods- genotyping 2a) PCR-SSP
2b) PCR-SSO 2c) PCR-SBT
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Cross-match testing determination of preformed alloantibodies
recipient serum + donor lymphocytes + rabbit complement → if cytotoxic Ab against donor HLA Ag are present in recipient serum , Ab activate complement → lysis of donor lymphocytes Dye penetration into lysis cells. positive test = the presence of preformed Ab → risk of hyperacute rejection! → contraindication to transplantation 17
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FACS crossmatch Mulley WR et al. Nephrology 16: , 2011
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Mixed lymphocyte reaction (MLR)
Two – way MRL determination of T lymphocytes alloreactivity mixed donor and recipient lymphocytes → T lymphocytes after recognition of allogeneic MHC gp activate and proliferate this assay was used to study possible donor - recipient incompatibilities for graft transplants to help predict better outcomes 19
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One-way MRL determination of recipient T lymphocytes reactivity against donor cells donor cells treated with chemotherapy or irradiated lose the ability of proliferation
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Rejection hyperacute accelerated acute chronic
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Hyperacute rejection minutes to hours after transplantation
humoral mediated immune response mechanism: if in recipients blood are present preformed or natural Ab (IgM anti- carbohydrate Ag) before transplantation → Ab + Ag of graft (MHC gp or endothelial Ag) → graft damage by activated complement the graft endothelium: activation of coagulation factors and platelets, formation thrombi, accumulation of neutrophil granulocytes prevention: negative cross match before transplantation, ABO compatibility 22
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Accelerated rejection
3 to 5 days after transplantation caused by antibodies that don´t activate complement cytotoxic and inflammatory responses triggered by binding of antibodies to Fc-receptors on phagocytes and NK cells prevention: negative cross match before transplantation, ABO compatibility 23
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Acute rejection days to weeks after the transplantation or after a lack of immunosuppressive treatment cell-mediated immune response mechanism: reaction of recipient TH1 and TC cells against Ag of graft tissue infiltration by lymphocytes, monocytes, granulocytes around small vessels → destruction of tissue transplant 24
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Chronic rejection from 2 months after transplantation
the most common cause of graft failure mechanism is not fully understood: non-immunological factors (tissue ischemia) and TH2 response with production alloantibodies, pathogenetic role of cytokines and growth factors (TGFβ) fibrosis of the internal blood vessels of the transplanted tissue, endothelial damage →impaired perfusion of graft → gradual loss of its function dominating findings: vascular damage 25
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Rejection Factors: The genetic difference between donor and recipient, especially in the genes coding for MHC gp (HLA) Type of tissue / organ - the strongest reactions against vascularized tissues containing many APC (skin) The activity of the recipient immune system – the immunodeficiency recipient has a smaller rejection reaction; immunosuppressive therapy after transplantation – suppression of rejection Status of transplanted organ - the length of ischemia, the method of preservation, traumatization of organ at collection 26
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Graft-versus-host (GvH) disease
after bone marrow transplantation GvH also after blood transfusion to immunodeficiency recipients T-lymphocytes in the graft bone marrow recognize recipient tissue Ag as foreign (alloreactivity) 27
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Acute GvH disease days to weeks after the transplantation of stem cells damage of liver, skin and intestinal mucosa prevention: appropriate donor selection, the removal of T lymphocytes from the graft and effective immunosuppression
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Chonic GvH disease months to years after transplantation
infiltration of tissues and organs by TH2 lymphocytes, production of alloantibodies and cytokines → fibrosis process like autoimmune disease: vasculitis, scleroderma, sicca-syndrome chronic inflammation of blood vessels, skin, internal organs and glands, which leads to fibrosis, blood circulation disorders and loss of function 29
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Graft versus leukemia effect (GvL)
donor T lymphocytes react against residual leukemick cells of recipient (setpoint response) mechanism is consistent with acute GvH associated with a certain degree of GvH (adverse reactions) 30
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Immunopathological (hypersensitivity) reactions
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Immunopathological reactions
Immune response which caused damage to the body (Consequence of immune response against pathogens, inappropriate responses to harmless antigens; autoimmunity)
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Immunopathological reactions
Classification by Coombs and Gell IV types of immunopathological reactions: Type I reaction - response based on IgE antibodies Type II reaction - response based on antibodies, IgG and IgM Type III reaction - response based on the formation of immune complexes Type IV reaction - cell-mediated response 33
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Immunopathological reaction type II (cytotoxic hypersensitivity reactions)
Cytotoxic antibodies IgG and IgM bind to cell surface antigens on own cells: complement activation binding to Fc receptors on phagocytes and NK cells (ADCC) 34
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Examples of immunopathological reaction type II
Transfusion reactions after administration of incompatibile blood: binding of antibodies to antigens on erythrocytes → activation of the classical pathway of complement → cell lysis Hemolytic disease of newborns: caused by antibodies against RhD antigen
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Examples of immunopathological reaction type II
Autoimmune diseases: organ-specific cytotoxic antibodies (antibodies against erythrocytes, neutrophils, thrombocytes, glomerular basement membrane ...) blocking or stimulating antibodies Graves - Basedow's disease - stimulating antibodies against the receptor for TSH Myasthenia gravis - blocking of acetylcholin receptor→ blocking of neuromuscular transmission Pernicious anemia - blocking the absorption of vitamin B12 Antiphospholipid syndrome - antibodies against fosfolipids Fertility disorder - antibodies against sperms or oocytes 36
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Immunopathological reaction type III (immune-complex reactions)
circulating antigen- IgG antibody immune complexes that deposit in tissues immunocomplexes - activate complement - bind to Fc receptors on phagocytes immune complexes, depending on the quantity and structure, are eliminated by phagocytes or stored in tissues 37
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Immunopathological reactions type III
pathological immunocomplexes response arises when is a large dose of antigen, or antigen in the body remains; arise days after aplication of Ag and induced inflamation (can get to chronic state) immune complexes are deposited in the kidneys (glomerulonephritis), on the surface of endothelial cells (vasculitis) and in synovie joint (arthritis)
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clinical manifestations: urticaria, arthralgia, myalgia
Serum sickness the therapeutic application of xenogeneic serum (antiserum to snake venom) creation of immune complexes and their storage in the vessel walls of different organs clinical manifestations: urticaria, arthralgia, myalgia Systemic lupus erythematosus antibodies against nuclear antigens, ANA, anti-dsDNA Farmer's lung IgG antibody against inhaled antigens (molds, hay) Post-streptococcal glomerulonephritis, cryoglobulinemia, revmatoid arthritis, post-infectious arthritis 39
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Immunopathological reaction type IV (delayed-type reaction - DTH)
local reaction caused by TH1 cells and monocytes/macrophages (physiologically –defense against intracellular pathogens) immunization by antigen → formation of antigen specific TH1 cells and memory cells 12-48 hours after next antigen exposure arise local reaction → granuloma (TH1 and macrophage infiltration) Tuberculin skin tes reaction Tissue damage in tuberculosis and leprosy Sarcoidosis Multiple sclerosis 40
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Subtype IV - Cellular cytotoxic response (Tc activation)
similar to DTH reaction TH1 cells activate CD8 + T lymphocytes viral rashes viral hepatitis acute rejection of transplanted organ some autoimmune thyroiditis contact dermatitis
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Contact dermatitis is a localized rash or irritation of the skin caused by contact with alergen (nickel , chromium, ingredients in cosmetic products , plant allergens and other) the first is senzitization appears in 24 – 48 hours after second contact with alergen diagnosis : patch test
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Patch test patch test is a method used to determine if a specific substance causes allergic inflamation of the skin Allergens are applied to special hypoallergenic patch on the back skin Results are evaluated after 48 and 72 hours In positive reaction appears eczema
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Thank you for your attention
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Tumour immunology and immunotherapy
Q8zsg This is how your immune system fights cancer qFZV3o
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