What is immunology?
What is Tumor?
Types of tumor
Classification of Malignant tumors
Malignant transformation of cells
General features of Tumor immunity
Tumor antigens
Tumor specific antigen
Tumor associated antigens
Immune response to tumor
Evasion of immune response by tumor
Cancer Immunosurveillance versus Immunoediting
Immunotechniques
RIA
ELISA
1. Report On Seminar Topic Entitles
“Tumor Immunology”.
Submitted in partial fulfilment of M.Sc. II Semester III to the Post Graduate Department of Zoology,
Hislop College, RTM Nagpur University
By
Nidhi Lilhare
Under the supervision of
Dr. R. J. Andrew
Dr. Payal Verma
Dr. Nilesh Thaokar
Mrs. Reena Agrawal
Post Graduate Department of Zoology
Hislop College Nagpur
2019-20
2. Contents
What is immunology?
What is tumor?
Tumor origin
Types of tumor
Classification of malignant tumor
Malignant transformation of cell
Tumor antigen
Immune response to tumor
RIA
ELISA
3. What is immunology?
Immunology has its origins in the study of how
the body protects itself against foreign
invasion in body that is harmful to our body.
Our immunity decides our resistance and
susceptibility to foreign harmful invasions.
These foreign invaders can be any
microorganisms, such as bacteria, viruses,
protozoa, and fungi, and also parasitic
organisms, such as helminth worms.
4. What is Tumor?
A tumor is defined as a swelling or morbid
enlargement that results from an
overabundance of cell growth and
division; normally cells grow and divide to
produce new cells in a controlled and
orderly manner.
Tumor cells are self cells that have
escaped normal growth regulating
mechanisms.
5. Types of tumor
There are two types tumors. These
are:
Benign Tumor: A tumor that is
encapsulated and does not invade
the healthy surrounding tissue is
benign.
Malignant tumor: A Tumor that grows
uncontrolled invasive, progressive,
destructive and that exhibit
metastasis is malignant. These
tumors are called cancer.
6. Classification of Malignant tumors.
Malignant tumors are classified according to
embryonic origin of the tissue from which the tumor
is derived.
Carcinomas: These arise from the endodermal or
ectodermal origin.
Sarcomas: Arise from mesodermal connective tissue.
Leukemia, Lymphoma and myeloma are malignant
tumors of hematopoietic cells of the bone marrow.
7. Malignant transformation of cells
Treatment of normal cultured cells with chemical
carcinogens, irradiations, and certain viruses can
alter their morphology and growth properties.
In some cases this process is called as
transformation, makes the cells able to produce
tumors when injected into animals.
Such cells are said to undergone malignant
transformation, and they often exhibit properties
in vitro similar to those of cancer cells.
For example, they have decreased requirement for
growth factors and serum, and are no longer
anchorage dependent, and grow in density-
independent fashion.
8. General features of Tumor immunity
Tumor express antigens that are recognized
as foreign by the immune system of the
tumor bearing host.
Though tumor cells are derived from host
cell they are capable of elicit immune
response. The first experimental
demonstration that tumor can induce
protective immune response came from
studies of transplanted tumors in 1959s.
Immune responses frequently fail to
prevent the growth of tumors.
Experimental demonstration of tumor immunity
9. Tumor antigens
Two types of tumor antigens have been
identified on the surface of tumor cells:
Tumor specific transplantation antigens
(TSTAs)
Tumor associated transplantation antigen
(TATAs)
10. Tumor specific antigen
Tumor-specific antigen have been identified on tumor induced with
chemical or physical carcinogens and on virally induced tumors.
Demonstrating the presence of tumor specific antigens on spontaneously
occurring tumors is particularly difficult because the immune response
to such tumors eliminates all of the tumor cells bearing sufficient
numbers of the antigens and in this way selects for cells bearing low
levels of the antigens.
Methylcholanthrene and ultraviolet light are two carcinogens that have
been used extensively to generate lines of tumor cells.
11. Tumor associated antigens
These antigens may be present in the normal cells.
Oncofetal tumor antigens: As the name implies, are found not only on cancerous cells but also
on normal fetal cells.
These antigens appear early in embryonic development, before the immune system acquires
immunocompetence, if these cells appear later on cancer cells, they are recognized as non-
self and induce immunological response.
Two well-studied oncofetal antigens are alpha-fetoprotein(AFP) and carcinoembryonic antigen
(CEF).
Oncogene proteins as tumor antigen: These proteins are also present in normal cells encoded
by corresponding proto oncogene.
In many cases, there is no qualitative difference between oncogene and proto oncogene
products, instead increased level of oncogene product can be recognized by immune system.
13. Immune response to tumor
CTLs perform a surveillance function by recognizing and killing potentially
malignant cells that express peptides derived from mutant cellular
proteins or oncogenic viral proteins.
The principal mechanism of tumor immunity is killing of tumor cells by
CD8+ CTLs.
CD8+ T-cells responses specific for tumor antigens may require cross
presentation of the tumor antigen by professional APCs, such as dendritic
cells.
Tumor bearing hosts may produce antibodies against various tumor
antigens.
NK cells kill many types of tumor cells specially cells that have reduced
class-I MHC expression and can escape killing by CTLs.
The role of macrophages in anti-tumor immunity is largely inferred from
the demonstration that in vitro, activated macrophages can kill many
tumor cells more efficiently then they can kill normal cells.
15. Evasion of immune response by tumor
Many malignant tumor possess mechanism that enable them to evade
or resist host immune responses.
The process of evasion, often called as tumor escape, maybe a result of
several mechanism.
Class-I MHC expression may be downregulated on tumor cells so that
they cannot be recognized by CTLs.
Tumor lose expression of antigen that elicit immune responses.
Tumors may fail to induce CTLs because most tumor cells do not
express co-stimulators or class-II MHC molecules.
The product of tumor cell may supress anti-tumor immune responses.
Tumor antigens may induce specific immunologic tolerance.
16.
17. Cancer Immunosurveillance versus
Immunoediting
Cancer immunoediting process is envisaged to consist of three phases: elimination,
equilibrium, and escape .
Elimination phase corresponds to the original concept of cancer immunosurveillance,
whereby nascent tumor cells are successfully recognized and eliminated by the immune
system, thus returning the tissues to their normal state of function.
tumor cells that elude the immunosurveillance phase will progress to the immune editing
phase, called the equilibrium phase of advanced oncogenesis, where tumor expansion and
metastasis are minimal (tumor dormancy) and usually occur without symptoms.
In the equilibrium phase, the immune system may eventually eliminate all tumor cells
leading to an outcome similar to the elimination phase. In a second scenario, the constant
interaction of the immune system with tumor over a long period of time may actually
“edit” or sculpt the phenotype of the developing tumor, resulting in the immunoselection
of a tumor that has been shaped into a less-immunogenic state.
tumor that are no longer susceptible to immune attack then progress into the
immunoediting process, termed “escape.” The emergence of clinical symptoms of cancer
generally correlates with the escape stage.
tumor subverts the immune system, either directly through its nonimmunogenic
phenotype, or indirectly through a variety of immunosuppressive mechanisms.
18. Immunotechniques
Two immune techniques will be discussed here:
Radioimmunoassay (RIA)
Enzyme linked immunosorbent assay(ELISA)
19. RIA
Radioimmunoassay (RIA) is an in vitro assay that measures the presence of an
antigen with very high sensitivity. Basically any biological substance for which a
specific antibody exists can be measured, even in minute concentrations.
Radioimmunoassay (RIA) method:
The target antigen is labeled radioactively and bound to its specific antibodies
(a limited and known amount of the specific antibody has to be added). A
sample, for example a blood-serum, is then added in order to initiate a
competitive reaction of the labeled antigens from the preparation, and the
unlabeled antigens from the serum-sample, with the specific antibodies. The
competition for the antibodies will release a certain amount of labeled
antigen. This amount is proportional to the ratio of labeled to unlabeled
antigen. A binding curve can then be generated which allows the amount of
antigen in the patient's serum to be derived.
20. Cont….
That means that as the concentration of unlabeled
antigen is increased, more of it binds to the
antibody, displacing the labeled variant. The bound
antigens are then separated from the unbound ones,
and the radioactivity of the free antigens remaining
in the supernatant is measured. A binding curve can
be generated using a known standard, which allows
the amount of antigens in the patient's serum to be
derived.
Radioimmunoassay is an old assay technique but it is
still a widely used assay and continues to offer
distinct advantages in terms of simplicity and
sensitivity.
21. ELISA
ELISA (enzyme-linked immunosorbent assay) is a plate-based assay technique
designed for detecting and quantifying peptides, proteins, antibodies and
hormones. In an ELISA, an antigen must be immobilized to a solid surface and
then complexed with an antibody that is linked to an enzyme.
Detection is accomplished by assessing the conjugated enzyme activity via
incubation with a substrate to produce a measurable product. The most crucial
element of the detection strategy is a highly specific antibody-antigen
interaction.
In ELISA, various antigen-antibody combinations are used, always including an
enzyme-labeled antigen or antibody, and enzyme activity is measured
colorimetric ally.
The enzyme activity is measured using a substrate that changes color when
modified by the enzyme. Light absorption of the product formed after substrate
addition is measured and converted to numeric values.
Depending on the antigen-antibody combination, the assay is called a direct
ELISA, indirect ELISA, sandwich ELISA, competitive ELISA etc.
22. Direct ELISA
A target protein (or a
target antibody) is
immobilized on the surface
of microplate wells and
incubated with an enzyme-
labeled antibody to the
target protein (or a
specific antigen to the
target antibody). After
washing, the activity of
the microplate well-bound
enzyme is measured.
23. Indirect ELISA
A target protein is immobilized on
the surface of microplate wells and
incubated with an antibody to the
target protein (the primary
antibody), followed by a secondary
antibody against the primary
antibody. After washing, the activity
of the microplate well-bound
enzyme is measured.
Although indirect ELISA requires
more steps than direct ELISA,
labeled secondary antibodies are
commercially available, eliminating
the need to label the primary
antibody.
24. Sandwich ELISA
An antibody to a target protein
is immobilized on the surface
of microplate wells and
incubated first with the target
protein and then with another
target protein-specific
antibody, which is labeled with
an enzyme.
After washing, the activity of
the microplate well-bound
enzyme is measured.
The immobilized antibody
(orange) and the enzyme-
labeled antibody (green) must
recognize different epitopes of
the target protein.
25. Summary
Tumor cells are self cells that have escaped normal growth regulating
mechanisms.
There are two types of tumor benign tumor and malignant tumor.
Malignant tumor are also referred to as cancer.
There are two types of tumor antigens:
tumor associated transplantation antigen
Tumor specific transplantation antigen
Basic response to tumor by immune system is immunosurveillance.
We discussed two types of immunotechniques: RIA & ELISA
26. References
R. Goldsby, T. Kindt & B. Osborne, Kuby immunology, fourth edition,
Page No. 540-553
A. Abbas & A. Lichtman, Cellular and Molecular Immunology, Page No.
401-403
https://www.verywellhealth.com/what-does-malignant-and-benign-
mean-514240
https://www.immunopaedia.org.za/immunology/special-focus-area/2-
cancer-tumors/immune-responses-to-cancer/
https://www.antibodies-
online.com/resources/17/1215/radioimmunoassay-ria/
http://ruo.mbl.co.jp/bio/e/support/method/elisa.html
https://openi.nlm.nih.gov/detailedresult?img=PMC5354689_oncotarge
t-08-10650-g001&req=4
