What Is Tumor Immunity?

Tumor immunity (tumor immunology) is the science that studies the correlation between tumor antigens, the body's immune function and tumorigenesis, development and outcome; the body's immune response to tumors and the immune effects of tumor cells; and the science of tumor immune diagnosis and immune prevention.

Tumors are the product of malignant transformation of normal cells in the body, which are characterized by continuous proliferation and metastasis in the body. Therefore, the prominent immunological characteristic of tumor cells is the emergence of some new antigenic markers that are not seen in similar normal cells. Tumor antigens have been discovered successively including tumor-specific antigens and tumor-associated antigens. The former is unique to tumor cells; the latter mostly refers to embryonic antigens, which are common to embryonic tissues and tumor tissues.

Chinese name: Tumor immunity
Foreign name: tumor Immunology

Antigen classification: Specific and related antigens
Immune response: Cellular and humoral immunity

Tumor immune tumor antigen classification

1. Tumor-specific antigen: refers to a new antigen that exists only on the surface of certain tumor cells and does not exist in normal cells.

2. Tumor-associated antigen: refers to the glycoprotein or glycolipid components on the surface of some tumor cells, which are slightly expressed on normal cells, but the expression is significantly increased in tumor cells.

Tumor immune response

The body's immune system eliminates tumor cells or inhibits their growth in a variety of ways. The body's anti-tumor immune response includes cellular immunity and humoral immunity.

1. Cellular immunity: It is the main tumor immune response. As a specific immune response, it mainly produces immune responses against strong antigenicity and solid tumor cells.

2. Humoral immunity: play a synergistic role. As non-specific immune responses, circulating antibodies, etc., mainly produce immune responses against tumor cells with weak antigenicity and free state.

Tumor immunity

Although there are a series of immune surveillance mechanisms in the body, it is still difficult to prevent the occurrence and development of tumors. A small number of tumor cells are not easy to cause the body to respond. When the tumor grows to a certain extent, beyond the body's ability to respond to the immune response, the tumor cells can escape. The mechanism of tumor immune escape involves multiple immune response links.

1. Immune selection: Tumor cells with strong antigenicity can cause an effective immune response to be eliminated, and tumor cells with relatively weak antigenicity can escape the surveillance of the immune system and proliferate.

2. Antigen modulation: The antigenicity on the surface of tumor cells is reduced or lost to evade the role of host immune system recognition and attack.

3. Tumors cause immunosuppression: When tumor cells first appear, the amount of antigen is small and weak. Continuous stimulation of the host can induce immune tolerance and make the host lose its immune response ability to the tumor.

4. Blocking factors: Blocking factors that cause immune boosting include blocking antibodies, excessive free antigens, and antigen-antibody complexes. The body can produce cytotoxic antibodies and blocking antibodies to tumors. Cytotoxic antibodies can cooperate with complement or NK cells to kill and lyse tumor cells. However, the binding of tumor cell shedding antigen to these antibodies can prevent the cytotoxic effects of these antibodies. The binding of blocking antibodies to tumor cells is not only harmless to the tumor, but prevents the killing effect of sensitized lymphocytes and cytotoxic antibodies on tumor cells.

Tumor immunodiagnosis

Biochemical and immunological techniques are used to detect tumor markers to assist tumor diagnosis. Common tumor markers include tumor antigens, hormones, oncogenes and their expressed proteins.

1. Tumor immunity 1. embryo-like antigen

Embryoid antigens are synthesized from embryonic tissues and are present in fetal serum and amniotic fluid. They are reduced after birth, but they are significantly increased when certain tumors occur. They are called embryonic antigens. Embryonic tumor-like markers include alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA).

(1) Alpha-fetoprotein (AFP) is synthesized by hepatocytes and yolk sacs during embryonic period and is present in fetal serum. The fetal serum content is highest in April to May, and then gradually decreases with gestational age, and decreases rapidly after birth. disappear. The content of normal adult serum is extremely low, and the normal reference value of AFP is <25ng / ml.

Elevated AFP levels are common in: Primary liver cancer. When primary liver cancer occurs, the serum AFP content increases in about 70% of patients, but some patients have normal AFP content; Cirrhosis and viral hepatitis, patient serum AFP content will increase to varying degrees; pregnancy, women's serum AFP content increases after 3 months of pregnancy, peaks at 7-8 months, and returns to normal 3 weeks after delivery; reproductive system tumors and embryo tumors Patients with teratoma, testicular cancer often have elevated AFP levels.

(2) Carcinoembryonic antigen (CEA) is present in the gastrointestinal tube, pancreas and liver of the fetus at 2 to 6 months, and the content in the tissue after birth is very low. The normal reference value is <5.0ng / ml.

CEA elevation is common in patients with gastrointestinal (colon, rectum, pancreas) malignant tumors, breast cancer, lung cancer and other malignant tumors.

2.SF Tumor immunity 2. serum ferritin (SF)

Diagnosis of liver, lung, pancreas and other cancers, acute leukemia, etc.

3.CA Tumor Immunization 3. Carbohydrate Antigens (CA) Recognized by Monoclonal Antibodies

Glycan antigens are tumor-associated antigens that are prepared using monoclonal antibodies from various tumor cell lines. Most of them are glycoproteins, and they are mostly on the surface of tumor cells. Such as CA50, CAl25, CAl5-3, CAl9-9, CA72-4, CA130, CA242 and so on.

(1) CA50 is a glycolipid antigen mainly composed of sialic acid and sialic glycoprotein, which plays an important role in information transmission, growth and differentiation of normal cells. It is mainly used for auxiliary diagnosis and progress monitoring of pancreatic cancer, colorectal cancer, gastric cancer, liver cancer, etc.

(2) CAl25 is a glycoprotein, which is present in the epithelial ovarian cancer tissues and the serum of patients. It is mainly used to help diagnose ovarian cancer, but in ovarian cysts, endometriosis, lung cancer, benign and malignant pleural ascites Positive reactions were also seen in.

(3) CAl5-3 is a breast cancer-associated antigen, which is of certain value for breast cancer diagnosis and postoperative follow-up monitoring, but its early sensitivity is low in breast cancer.

(4) CA1-9-9 is present in fetal pancreas, gallbladder, liver, intestine and other tissues, and its content is very low in normal human tissues. The content of CAl9-9 in the serum of patients with gastrointestinal malignant tumors was significantly increased. The detection of serum CAl9-9 can be used as an auxiliary diagnostic indicator of gastric cancer, pancreatic cancer, gallbladder cancer and other malignant tumors.

(5) CA72-4 is a high molecular glycoprotein carcinoembryonic antigen, a marker for gastrointestinal tumors and ovarian cancer, and has a specificity for the diagnosis of gastric cancer better than sugar chain antigen 19-9 and carcinoembryonic antigen. Can be used to diagnose gastric, ovarian, colorectal, breast, and pancreatic cancer.

(6) CA130 can be used to diagnose ovarian cancer and endometrial cancer.

(7) CA242 can be used to diagnose gastrointestinal tumors.

4. Tumor immunity 4. Hormones

When malignant changes occur in tissues that do not produce hormones, some peptide hormones are released.

(1) Human chorionic gonadotropin (HCG) is a glycoprotein hormone secreted by placental trophoblast cells. The entire HCG is produced by the trophoblast of the placental chorion. HCG testing is an important indicator for monitoring early pregnancy. Under abnormal conditions, trophoblastic tumors and germ cell tumors, such as hydatidiform moles and malignant hydatidiform moles, chorionic epithelial cancer, and testicular teratoma cancer, can significantly increase HCG.

(2) Calcitonin (CT) is mainly a peptide hormone secreted by thyroid follicle C cells. The main function of calcitonin is to reduce blood calcium content. Elevated levels are common in medullary thyroid cancer, small cell lung cancer, pancreatic cancer, uterine cancer, breast cancer, prostate cancer, benign adenoma of thyroid cells, and acute or chronic renal failure. Reductions are common in severe hyperthyroidism and hypothyroidism.

5. Tumor immunity 5. Enzymes

Including prostate-specific antigen, prostate acid phosphatase, neuron-specific enolase and -L-fucosidase. Enzymes are one of the early tumor markers used in clinical diagnosis.

(1) The normal value of prostate specific antigen (PSA) is less than 4 micrograms / liter, and the positive rate in prostate cancer is as high as 30% to 86%, and its elevation is closely related to tumors.

(2) The normal value of neuron-specific enolase (NSE) is <15 g / L. It is currently considered a tumor marker for small cell lung cancer and neuroblastoma. Elevated levels of NSE in serum are common in small cell lung cancer, neuroblastoma, neuroendocrine tumors, and hypoxic-ischemic brain damage.

(3) -L-fucosidase (AFU) 234 to 414 mol / L. It is mainly used for the diagnosis of hereditary AFU deficiency and to distinguish it from other hereditary mucopolysaccharidosis. The serum AFU of patients with primary liver cancer, chronic hepatitis, cirrhosis, bile duct cancer, colon cancer, uterine cancer, breast cancer, and lung cancer significantly increased. Women's serum AFU can also increase during pregnancy, but can decrease rapidly after delivery.

Tumor immunity

1. Tumor immunity 1. active immunotherapy

Therapies that stimulate and enhance the host's anti-tumor immune response. Active immunotherapy is divided into two types, specific and non-specific. The former uses tumor-specific antigens, and the latter uses substances that can non-specifically stimulate the immune system. Active immunotherapy is suitable for host with immune response ability and / or tumor with immunogenicity.

2. Tumor immunity 2. Passive immunotherapy

Therapies that treat tumors by injecting a host with a conjugate of effector cells and / or antibodies that can directly kill the tumor. When the therapeutic factor is a cell, it is called adoptive immunotherapy. Passive immunotherapy does not depend on the immune function status of the host.