Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Antitumour immunity J. Ochotná Hypothesis of immune control • tumor cells normally arise in tissues and are eliminated by T lymphocytes Malignant transformation • Failure of cell division regulation and regulation of cells "social" behavior • The uncontrollable proliferation, dissemination to other tissues • Mutations in protoonkogenes and antionkogenes Tumour antigens Tumour specific antigens (TSA) a) complexes of MHCgp I with abnormal fragments of cellular proteins chemically induced tumors leukemia with chromosomal translocation b) complexes of MHC gp with fragments of oncogenic viruses proteins tumors caused by viruses (EBV, SV40, polyomavirus) c) abnormal forms of glycoproteins Sialylation of surface proteins of tumor cells d) idiotypes of myeloma and lymphoma clonotyping TCR and BCR Tumour associated antigens (TAA) • expressed also on normal cells • differences in quantity, time and local of expression • auxiliary diagnostic markers a) onkofetal antigens • on normal embryonic cells and some tumor cells • -fetoprotein (AFP) - hepatom • canceroembryonal antigen (CEA) - colon cancer b) melanoma antigens • MAGE-1, Melan-A Tumour associated antigens (TAA) c) antigen HER2/neu • receptor for epithelial growth factor • mammary carcinoma d) EPCAM • epithelial cell adhesion molecule • metastases e) differentiation antigens of leukemic cells • present on normal cells of leukocytes linage • CALLA -acute lymphoblastic leukemia (CD10, pre-B cells) Defensive immune response • DC are necessary for activation of antigen specific mechanisms • cancer-associated antigens are processed by DC and presented to T lymphocytes in complexes with HLA I and II • predominance of TH1 (IFN TNF); IFN support DC maturation • tumor cells are eliminated by TC Defensive immune response • tumor cells are also destroyed by NK cells (low HLA I expression on tumor cells) • interferons - antiproliferative, cytotoxic effect on tumor cells - INF - DC maturation • TH2 activation → support B lymphocytes→ tumor specific antibodies (complement activation, opsonisation, ADCC) Mechanisms of tumor resistance high variability of tumor cells low expression of tumor antigens sialylation tumor cells do not provide costimulatory signals → T lymphocyte anergy Mechanisms of tumor resistance some antitumor substances have a stimulating effect on tumor production of factors inactivating T lymphocytes expression of FasL → T lymphocyte apoptosis inhibition of the dendritic cell functions and durability (NO, IL-10, TGF- Transplantation 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 other species Allogeneic transplantation • differences in donor-recipient MHC gp and secondary histocompatibility Ag • alloreactivity of T lymphocytes - the risk of rejection and graftversus-host • direct recognition of alloantigens – recipient T lymphocytes recognize the different MHC gp and non-MHC molecules on donor APC • indirect recognition of alloantigens - APC absorb different MHC gp from donor cells and present the fragments to T lymphocytes Recognition of alloantigens Tests prior to transplantation ABO Compatibility -risk of hyperacute or accelerated rejection = formation of Ab against A or B Ag on graft vascular endothelium) HLA typing (determination of MHC gp alelic forms) phenotyping and genotyping by PCR Cross-match - lymfocytotoxic test - testing preformed Ab (after blood transfusions, transplantation, repeated childbirth) Mixed lymphocyte reaction - test for T lymphocytes alloreactivity HLA typing Determmination of HLA antigens on the surface of lymphocytes Carry out during the testing before transplantation and in determination of paternity HLA typing Serotyping Genotyping (PCR SSP, PCR SSO, PSR SBT) HLA typing Serotyping Microlymfocytotoxic test Allospecific serums (obtained from multiple natal to 6 weeks after birth, obtained by vaccination of volunteers, or commercially prepared sets of typing serums (monoclonal antibodies)) Principle - the incubation of lymphocytes with typing serums in the presence of rabbit complement, then is added the vital dye which stain dead cells - cells carrying specific HLA are killed by cytotoxic Ab against the Ag, the percentage of dead cells is a measure of serum toxicity (forces and antileukocyte antibody titre) Positive reaction is considered more than 10% dead cells (serological typing can be done also by flow cytometry) HLA typing Serotyping (phenotyping) PCR-SSP = Polymerase chain reaction with sequential specific primers Extracted DNA is used as a substrate in a set of PCR reactions Each PCR reaction contains primers pair specific for a certain allele (or group of alleles) Positive and negative reactions are evaluated by electrophoresis, each combination of alleles has a specific electrophoretic painting PCR-SSO PCR reaction with sequence-specific oligonucleotides Multiplication of hypervariable sections of genes coding HLA Hybridization with enzyme or radiolabeled DNA probes specific for individual alleles PCR-SBT Sequencing based typing The most accurate method of HLA typing We get the exact sequence of nucleotides, which compares with a database of known sequences of HLA alleles Cross-match test • determination of preformed antibodies • recipient serum + donor lymphocytes + rabbit complement → if cytotoxic Ab against donor HLA Ag are present in recipient serum (called alloantibodies = Ab activating complement) → lysis of donor lymphocytes. Visualization of dye penetration into lysis cells. • positive test = the presence of preformed Ab → risk of hyperacute rejection! → contraindication to transplantation Mixed lymphocyte reaction (MRL) • determination of T lymphocyte alloreactivity • mixed donor and recipient lymphocytes → T lymphocytes after recognition allogeneic MHC gp activate and proliferate • the total proliferation of lymphocytes is measured by adding [3H]-thymidine to the culture medium and monitoring its integration to DNA of new cells One-way MRL •determination of recipient T lymphocytes reactivity against donor cells •donor cells treated with chemotherapy or irradiated lose the ability of proliferation 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 much APC (skin) The activity of the immune system of the recipient - the immunodeficiency recipient has a smaller rejection reaction; immunosuppressive therapy after transplantation – suppression of rejection Status transplanted organ - the length of ischemia, the method of preservation, traumatization of organ at collection Hyperacute rejection • minutes to hours after transplantation • antibodies immune response mechanism: • in recipients blood are present before transplantation preformed or natural Ab (IgM anti-carbohydrate Ag) → Ab + Ag of graft (MHC gp or endothelial Ag) → graft damage by activated complement (lysis of cells) • the graft endothelium: activation of coagulation factors and platelets, formation thrombi, accumulation of neutrophil granulocytes prevention: • negat. cross match before transplantation, ABO compatibility Hyperacute rejection Accelerated rejection Accelerated rejection • 3 to 5 days after transplantation • caused by antibodies that don‘t activate complement • cytotoxic and inflammatory responses activated by antibodies which bind to Fc-receptors on phagocytes and NK cells prevention: • negative cross match before transplantation, ABO compatibility Acute rejection • days to weeks after the transplantation or after a lack of immunosuppressive treatment • cell-mediated immune response mechanism: • recipient TH1 and TC cells response against Ag of graft tissue • infiltration of lymphocytes, mononuclears, granulocytes around small vessels → destruction of transplant tissue Chronic rejection • occures after 2 months from transplantation • the most common cause of graft failure mechanism is not fully understood: • non-immunological factors (tissue ischemia) and TH2 responses with production alloantibodies, pathogenetic role of cytokines and growth factors (TGF β) • replacement of functional tissue by fibrous tissue, endothelial damage →impaired perfusion of graft → gradual loss of its function dominating findings: vascular damage Bone marrow transplantation • hematopoetic stem cell collection • myeloablation • transplantation • engraftment • rejection • graft versus host disease Graft-versus-host disease (GVHD) • after bone marrow transplantation • GVHD also after blood transfusion to immunodeficiency recipients • T-lymphocytes in the graft bone marrow recognize recipient tissue Ag as foreign (alloreactivity) Acute GVHD • days to weeks after stem cells transplantation • damage of liver, skin and intestinal mucosa • Prevention: appropriate donor selection, T lymphocytes removal from the graft and effective immunosuppression Chronic GVHD • months to years after transplantation • TH2 lymphocytes infiltration of tissues and organs, production of alloantibodies and production of 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 Graft versus leukemia effect (GVL) • donor T lymphocytes react against residual leukemick cells of recipient • mechanism is consistent with acute GVHD • associated with a certain degree of GVHD (adverse reactions) Immunopathological reactions Classification by Coombs and Gell Immunopathological reactions: immune response, which caused damage to the body (secondary consequence of defense responses against pathogens, inappropriate responses to harmless antigens, autoimmunity) IV types of immunopathological reactions: Type I reaction - response based on IgE antibodies Type II reaction - response based on IgG and IgM antibodies Type III reaction - response based on the formation of immune complexes Type IV reaction - cell-mediated response Immunopathological reaction based on IgG and IgM antibodies (reaction type II) Cytotoxic antibodies IgG and IgM: • complement activation • binding to phagocytes and NK cells (ADCC) Fc receptors Haemolytic reactions after transfusion of ABO incompatible blood: Binding of antibodies to antigens of erythrocytes → activation of the classical way of complement → cell lysis Hemolytic disease of newborns: Caused by antibodies against RhD antigen Autoimmune diseases: • organ-specific cytotoxic antibodies (antibodies against erythrocytes, neutrophils, thrombocytes, glomerular basement membrane ...) • blocking or stimulating antibodies Graves - Basedow disease - stimulating antibodies against the TSH receptor Myasthenia gravis - blocking of acetylcholin receptor→ blocking of neuromuscular transmission Pernicious anemia - blocking of vitamin B12 absorption Antiphospholipid syndrome - antibodies against fosfolipids Fertility disorders - antibodies against sperms or oocytes Immunopathological reactions based on immune complex formation (reaction type III) • caused mainly by IgG antibodies → bind to antigen → creation of immunecomplexes • immunocomplexes - bind to Fc receptors on phagocyte - activate complement • immune complexes (depending on the quantity and structure) are eliminated by phagocytes or stored in tissues • pathological immunocomplexes response arises when is a large dose of antigen, or antigen in the body remains • immune complexes are deposited in the kidneys (glomerulonephritis), on the endothelial cells surface (vasculitis) and in synovial joints (arthritis) Serum sickness • after 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 antibodies against inhaled antigens (molds, pollens) Poststreptococcal glomerulonephritis Immunopathological delayed-type reaction (reaction type IV) • delayed-type hypersensitivity (DTH) • local reaction caused by TH1 cells and monocytes / macrophages (physiologically – elimination of macrophage intracellular parasites) • antigen immunization → formation of antigen specific TH1 cells (and memory cells) • 12-48 hours after next contact with antigen arise local reaction – granuloma (TH1 and macrophage infiltration) Tuberculin reaction Tissue damage in tuberculosis and leprosy Sarcoidosis 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 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 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 *Thank you for your attention Tumor immunotherapy Therapy - surgical removal of tumor - chemotherapy or radiotherapy - immunotherapy Immunotherapy - induction of anti-tumor immunity, or the use of immune mechanisms to targeting drugs to the tumor site Immunotherapy using antibodies Antibodies functions - opsonization - activation of complement - induction of ADCC - carriers of drugs or toxins 1) Monoclonal antibodies - against TAA - mouse and humanised antibodies - imunotoxins, radioimunotoxins - the possibility of damage surrounding tissues - HERCEPIN - Ab against HER2/neu, breast cancer - RITUXIMAB - Ab against CD20, lymphoma 2) Bispecific antibodies - bind a tumor antigen and the T lymphocyte or NK cell - Fc fragment of antibody binds to Fc receptors on phagocytes and NK cells 3) Elimination of tumor cells from the suspension of bone marrow cells using monoclonal antibodies for autologous transplantation Immunotherapy using cell-mediated mechanisms 1) stimulation of inflammation at the tumor site 2) stimulation of LAK and TIL - isolation of T and NK cells, stimulation by cytokines, and return to the patient - LAK (lymphokine activated killers) - TIL (tumor infiltrating lymphocytes) 3) improving of tumor cells antigenpresenting function - genetic modification of tumor cells - expression of CD80, CD86 - production of IL-2, GM-CSF - modified cells are irradiated and returned to the patient * the dendritic cell immunotherapy 5) tumor vaccines - in vitro stimulation of TH1 cells and TC with tumor antigens 6) immunotherapy by donor T lymphocytes - after allogeneic transplantation - causing graft-versus-host disease 7) immunotherapy by immune system products - IL-2 - renal cell carcinoma -IFN - hematoonkology 8) Anti CTLA-4 antibody - Treg inhibition, longer activation of effector T cells * Dendritic cell vaccine * dehttps://www.youtube.com/watch?v=Aaho7YV_r10 * Imunotherapy of cancer * https://www.youtube.com/watch?v=-NNjDjXSJt0 * Immunopathologycal reaction type IV * https://www.youtube.com/watch?v=e1X_7jqxEzA