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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• Protoonkogens
• promitotic (promoting cell division)
• for the malignant transformation is enough
  mutation in one copy of the gene protoonkogen
  (dominant oncogenes)

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• Antionkogens
• tumor-suppressor genes
• regulation of cell cycle
• for the malignant transformation should be
  excluded from
• function both copies of the gene (recessive
  oncogenes)
• TP53, RB1

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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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• cancer-associated antigens are processed by APC
  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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Cytotoxic mechanisms of NK cells
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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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• 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) tumor vaccines - in vitro stimulation of TH1
cells and TC with tumor antigens 5) 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 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
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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 - differences in donor-recipient MHC
gp and secondary histocompatibility Ag -
alloreactivity of T lymphocytes - the risk of
rejection and graft-versus-host - direct
detection 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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Testing before transplantation Compatibility in
the system ABO -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 DNA
typing of HLA class II DR, DP, DQ by PCR.
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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 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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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 the transplantation of stem cells ?
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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Immunologic relationship of mother and allogenic
fetus ? fetal cells have on the surface
alloantigens inherited from his father Tolerance
of fetus by mother allow the following
mechanisms ? the relative isolation of the
fetus from maternal immune system (no mixing of
blood circulation) ? trophoblast - immune
barrier witch protect against mother
alloreaktive T lymphocytes
- dont express classical MHC
gp, expresses
non-classical HLA-E and HLA-G ? depression of TH1
immune mechanisms in pregnancy Complications in
pregnancy production of anti-RhD antibodies by
RhD- mother carrying RhD fetus (hemolytic
disease of newborns)
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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 phagocytes
- 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 Experimenta
l model (testing of cellular immunity) ?
intradermal immunization by antigen ? creation of
antigen-specificTH1 cells ? after a few weeks
intradermal administration of antigen ? creates
local reaction (granuloma) - TH1 cells and
macrophages Tuberculin reaction Tissue damage in
tuberculosis and leprosy Sarcoidosis
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