Chapter 17

Question 1

Tumors express antigens that are recognized by

the immune system, but most tumors are what?

Answer 1

weakly
immunogenic, and immune responses often fail to
prevent the growth of tumors. The immune system
can be stimulated to effectively kill tumors

Question 2

Tumor antigens recognized by CTLs are the principal inducers of and targets for anti-tumor immunity. These antigens include what?

Answer 2

mutants of oncogenes
and other cellular proteins, normal proteins whose
expression is dysregulated or increased in tumors,
and products of oncogenic viruses.

Question 3

Antibodies specific for tumor cells recognize antigens that are used for diagnosis and are potential
targets for antibody therapy. These antigens
include what?

Answer 3

oncofetal antigens, which are expressed
normally during fetal life and whose expression is
dysregulated in some tumors; altered surface glycoproteins and glycolipids; and molecules that are
normally expressed on the cells from which the
tumors arise and are thus differentiation antigens
for particular cell types.

Question 4

Immune responses that are capable of killing

tumor cells consist of what?

Answer 4

CTLs, NK cells, and activated
macrophages. The role of these immune effector
mechanisms in protecting individuals from tumors
is not well defined

Question 5

Tumors evade immune responses by several

mechanisms, including downregulation of what?

Answer 5

expression of MHC molecules, outgrowth of cells that do
not express tumor antigens, production of immunosuppressive substances, and induction of tolerance to tumor antigens. Tumor-associated
macrophages and myeloid-derived suppressor
cells, found in most solid tumors, suppress antitumor immunity

Question 6

Immunotherapy for tumors is designed to augment what?

Answer 6

active immune responses against these tumors or
to administer tumor-specific immune effectors to
patients

Question 7

Immune responses may be actively

enhanced by ?

Answer 7

vaccination with tumor cells or antigens, administration of tumors modified to express
high levels of costimulators or cytokines that
stimulate T cell proliferation and differentiation,
and systemic administration of cytokines

Question 8

Antitumor immunity may also be enhanced by?

Answer 8

blocking inhibitory pathways of immunoregulation.
Approaches for passive immunotherapy include
the administration of anti-tumor antibodies, antibodies conjugated with toxic drugs (immunotoxins), and tumor-reactive T cells and NK cells
isolated from patients and expanded by culture
with growth factors.