HOST DEFENSE AGAINST
TUMORS:
TUMOR IMMUNITY
,• The idea that tumours are not entirely “self” was conceived by
Ehrlich, who proposed that immune-mediated recognition of
autologous tumour cells may be a “positive mechanism” capable o
eliminating transformed cells
• Subsequently, Lewis Thomas and Macfarlane Burnet formalized thi
concept by coining the term immune surveillance to refer to
recognition and destruction of newly appearing tumour cells, whic
are seen as foreign by the host immune system
• Occurrence of cancers implies that immune surveillance is imperfe
the escape of some tumours from such policing, however, does no
preclude the possibility that others may have been thwarted
, Tumour Antigens
• Initially broadly classified into two categories based on their patterns of
expression:
• Tumour-specific antigens, which are present only on tumour cells and not on any normal
• Tumour-associated antigens, which are present on tumour cells and also on some norma
cells
• Many antigens thought to be tumor-specific turned out to be expressed by some normal cells as we
• The modern classification of tumour antigens is based on their molecular
structure and source
• An important advance in the field of tumour immunology was the developme
of techniques for identifying tumour antigens that were recognized by cytotox
lymphocytes (CTLs), because CTLs are responsible for the major immune defe
mechanism against tumours
• CTLs recognize peptides derived from cytoplasmic proteins that are displayed
bound to class I major histocompatibility complex (MHC) molecules
TUMORS:
TUMOR IMMUNITY
,• The idea that tumours are not entirely “self” was conceived by
Ehrlich, who proposed that immune-mediated recognition of
autologous tumour cells may be a “positive mechanism” capable o
eliminating transformed cells
• Subsequently, Lewis Thomas and Macfarlane Burnet formalized thi
concept by coining the term immune surveillance to refer to
recognition and destruction of newly appearing tumour cells, whic
are seen as foreign by the host immune system
• Occurrence of cancers implies that immune surveillance is imperfe
the escape of some tumours from such policing, however, does no
preclude the possibility that others may have been thwarted
, Tumour Antigens
• Initially broadly classified into two categories based on their patterns of
expression:
• Tumour-specific antigens, which are present only on tumour cells and not on any normal
• Tumour-associated antigens, which are present on tumour cells and also on some norma
cells
• Many antigens thought to be tumor-specific turned out to be expressed by some normal cells as we
• The modern classification of tumour antigens is based on their molecular
structure and source
• An important advance in the field of tumour immunology was the developme
of techniques for identifying tumour antigens that were recognized by cytotox
lymphocytes (CTLs), because CTLs are responsible for the major immune defe
mechanism against tumours
• CTLs recognize peptides derived from cytoplasmic proteins that are displayed
bound to class I major histocompatibility complex (MHC) molecules
