|
You are here:
IMMUNOTECHNOLOGY>
Tumor Immunology > TUMOR ANTIGENS
TUMOR
ANTIGENS
Two types of tumor antigens have been identified
on tumor cells:
- Tumor specific transplantation antigens ( TSTAs)
- Tumor associated transplantation antigens (TATAs)
Tumor specific transplantation antigens are unique to tumor cells and
do not occur on normal cells in the body. They may result from
mutations in tumor cells that generate altered cellular proteins;
cytosolic processing of these proteins are presented with class I MHC
molecules inducing a cell mediated response by tumor specific CTLs.
Tumor associated transplantation antigens (TATAs) are not
unique to tumor cells; may be proteins that are expressed on
normal cells during fetal development when the immune system in
immature. Reactivation of the embryonic genes that encode these
proteins in tumor cells results in their expression on the fully
differentiated tumor cells. |
|
These TATAs can help diagnose various tumors hence used as
TUMOR MARKERS. These
are substances that can be found in the body( usually in blood &
urine) when cancer is present. They are generally detected by
combining blood or urine with man made antibodies designed to react
with them.
The first modern tumor marker used to detect cancer was
HUMAN CHORIONIC GONADOTROPIN (hCG).A
high level of hCG in the blood after pregnancy indicates cancer of the
placenta called Gestational trophoblastic disease (GTD).The second
tumor marker used was CARCINO EMBRYONIC ANTIGEN (CEA), found in the
blood of patients suffering with colon cancer.
COMMONLY
USED TUMOR MARKERS
|
|
CARCINO EMBRYONIC ANTIGEN:
- A protein polysaccharide complex
- present in colon carcinomas & in normal fetal intestine,
pancreas and liver.
- elevated levels are also found in chain smokers and in
patients with cirrhosis
- Monitoring CEA level may be useful fro detecting cancer
recurrence
ALPHA FETOPROTEIN
- A normal product of fetal liver cells.
- Elevated levels are present in sera of patients with
primary hepatoma, yolk sac neoplasm, ovarian or testicular
embryonal carcinoma
BETA SUBUNIT OF hCG
- Found in women with gestational trophoblastic
neoplasia & in about 2/3rd of men with testicular/
embryonal carcinoma/chorio caranoma.
|
PROSTATE SPECIFIC ANTIGEN
- A glycoprotein located in ductal epithelial cells
of the prostate gland
- Elevated levels are present in 90% of patients
with advanced prostate cancer
- Can be used to monitor the recurrence of the
prostate cancer.
CA125
- It is clinically useful for diagnosing &
monitoring therapy for ovarian cancer
BETA 2 MICROGLOBULIN
- this is often elevated in multiple myelloma &
in some lymphomas
CA 19-9
- used to detect colorectal cancer &
pancreatic cancer
- primarily used to judge the response to
treatment in patients with advanced pancreatic
cancers
- Also found elevated in other cancers of bile
duct.
|
|
CA 15-3
- Elevated in 50-80% patients suffering with
metastatic breast cancers
- primarily used to study the response to
therapy
CHROMOGRANIN A
- Used as marker for neuro-endocrine tumors.
- abnormal levels can be seen in metastatic
cancer patients of lung & prostate
THYROGLOBULIN
- Produced by thyroid
- primarily used after complete
thyroidectomy to detect recurrent thyroid
cancer & to follow the response to treatment
in metastatic thyroid cancer
TA 90
- it is a highly immunogenic subunit of
urinary tumor associated antigen
- present in 70 % of melanomas, soft
tissue sarcomas & carcinomas of the breast
colon & lung.
|
search
 EXAM
ALERT
BROWSE BY SUBJECTS
|
