Anti-tumor immunity

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• Anti-tumor immunity

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• Malignant transformation
• Failure of regulation of cell division and
  regulation of "social" behavior of the cells
• The uncontrollable proliferation, dissemination
  to other tissues
• Mutations in protoonkogenes and antionkogenes

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• Mutagens (carcinogens)
• - physical (eg various forms of radiation)
• - chemical (eg aromatic
  hydrocarbons)
• - biological (mainly various
  oncogenic
  viruses)

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Tumor antigens Antigens specific for tumors
(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 proteins of oncogenic viruses -
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
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Antigens associated with tumors (TAA) - also on
normal cells - differences in quantity, time and
local 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
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• c) antigen HER2/neu
• - receptor for epithelial growth factor
• - mammary carcinoma
• d) EPCAM
• - epithelial adhesion molecule
• - metastases
• e) differentiation antigens of leukemic cells
• - present on normal cells of leukocytes
  linage
• - CALLA -acute lymphoblastic leukemia (CD10
  pre-B cells)

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• Anti-tumor immune mechanisms
• Hypothesis of immune control
• tumor cells normally arise in tissues and are
  eliminated by T lymphocytes (probably wrong
  hypothesis)
• Defensive immune response
• tumor cells are weakly immunogenic
• occurs when tumor antigens are presented to T
  lymphocytes by activated dendritic cells
• in defense may be involved non-specific
  mechanisms (neutrophilic granulocytes,
  macrophages, NK cells, interferons) and
  antigen-specific mechanisms (complement
  activating antibodies or ADCC, TH1 and TC)

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Regulatory T cells prevents removal of cancer
cells and thus contribute to the development of
the tumor.
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• DC are necessary for activation of antigen
  specific mechanisms
• cancer-associated antigens are processed by DC
  and recognized by T lymphocytes in complex
  with HLA I. and II. class with providing
  costimulus signals
• predominance of TH1 (IFN ??? TNF??)
• specific cell-mediated cytotoxic reactivity TC
• activation TH2 ? support B lymphocytes? tumor
  specific antibodies (involved in the ADCC)
• tumor cells are destroyed by cytotoxic NK cells
  (low MHC gpI expression on tumor cells)
• interferons - antiproliferative, cytotoxic
  effect on tumor cells -
  INF? - DC maturation

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• Mechanisms of tumors resistance to immune system
• high variability of tumor cells
• low expression of tumor antigens
• sialylation
• tumor cells do not provide costimulus signals ?
  T lymphocyte anergy
• 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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Tumor immunotherapy Therapy - surgical
removal of tumor - chemotherapy or
radiotherapy - immunotherapy Immu
notherapy - induction of anti-tumor immunity, or
the use of immune
mechanisms to targeting drugs
to the tumor site
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Immunotherapy using antibodies Antibodies
functions - opsonization
- activation of complement
- induction of ADCC
- carriers of
drugs or toxins
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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
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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
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4) the dendritic cell immunotherapy- in vitro
cultivation of monocytes in an appropriate
cytokine environment (GM-CSF, IL-4) ?
transformation into dendritic cells- cultivation
of dendritic cells with tumor antigens
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• 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

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Transplantation
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• Transplantation
• transfer of tissue or organ
• autologous - donor recipient
• syngeneic - genetically identical donor
  recipient (identical
  twins)
• allogeneic - genetically nonidentical donor of
  the same species
• xenogenic - the donor of another species
• implant - artificial tissue compensation

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Allogeneic transplantation - differences in
donor-recipient MHC gp and secondary
histocompatibility Ag - alloreactivity of T
lymphocytes - the risk of rejection and
graft-versus-host - direct recognition of
alloantigens recipient T lymphocytes recognize
the different MHC gp and non-MHC molecules on
donor cells - indirect recognition of
alloantigens - APC absorb different MHC gp from
donor cells and present the fragments to T
lymphocytes - CD8 T cells recognize MHC gp
I. - CD4 T cells recognize MHC gp II.
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Recognition of alloantigens
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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
(determining 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 test - testing
of alloreactivity T lymphocytes monitor for
reactivity of lymphocytes to allogeneic HLA
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HLA typing a) phenotyping Evaluation of HLA
molecules using typing serums Typing antiserums
alloantiserums of multipar (created cytotoxic
Ab against paternal HLA Ag of their children),
serum of patients after repeated blood
transfusions, monoclonal Ab - molecules HLA
class I separated T lymphocytes - molecules HLA
class II separated B lymphocytes b)
genotyping evaluation of specific alleles
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• 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

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• Mixed lymphocyte reaction (MRL)
• determination of alloreactivity T lymphocytes
• 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

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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 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
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• Hyperacute rejection
• minutes to hours after transplantation
• antibodies type of 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

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• Accelerated rejection
• 3 to 5 days after transplantation
• caused by antibodies that dont activate
  complement
• cytotoxic and inflammatory responses activated
  by antibodies binding to Fc-receptors on
  phagocytes and NK cells
• prevention
• negative cross match before transplantation, ABO
  compatibility

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• 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

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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 responses with production alloantibodies,
  pathogenetic role of cytokines and growth
  factors (TGF ß)
• replacement of functional tissue by connective
  tissue, endothelial damage ?impaired
  perfusion of graft ? gradual loss of its
  function
• dominating findings vascular damage

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Bone marrow transplantation

• hematopoetic stem cell collection
• myeloablation
• transplantation
• engraftment
• rejection
• graft versus host disease

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• 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)

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• 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

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• Chronic GVHD
• months to years after transplantation
• TH2 lymphocytes infiltration of tissues and
  organs, production of alloantibodies and
  production of cytokines ? fibrotization
• process like autoimmune disease vasculitis,
  scleroderma, sicca-syndrome
• chronic inflammation of blood vessels, skin,
  internal organs and glands, which leads to
  fibrotization, blood circulation disorders and
  loss of function

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• 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)

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Immunopathological reactions
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Classification by Coombs and Gell Immunopathologi
cal 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
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• Immunopathological reaction based on IgG and IgM
  antibodies (reaction type II)
• Cytotoxic antibodies IgG and IgM
• complement activation
• ADCC
• binding to phagocytes and NK cells 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

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• 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

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• Immunopathological reactions based on immune
  complex formation (reaction type III)
• caused 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)

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• 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

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• 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

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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 determineif 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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