Cancer treatment: Share immune cells with the patient
Immune cells of healthy people will help in the fight against cancer
Cells of the immune system of healthy people can become a new weapon in the fight against cancer. Perhaps, unlike modern antitumor vaccines, the new approach will allow you to get rid of the disease forever.
According to Professor Johanna Olweus from the Institute of Immunology, part of the University of Oslo, the basis of the action of vaccines is the stimulation of the patient's own immune system to attack the tumor. Despite the enormous efforts expended by researchers around the world over the past decades, the results obtained are not good enough.
Professor Olveus and her colleagues have developed a fundamentally new approach to using the immune system to fight cancer. Instead of stimulating the immune system of the patient himself, from which it is difficult to achieve a strong immune response, they suggested using a pronounced immune response developed by the immune system of healthy people.
The patient's own immune cells cannot resist cancerIn order to understand the meaning of the new idea, it is necessary to understand the reasons for the difficulties associated with the development of antitumor vaccines.
Vaccination against infectious diseases is one of the greatest achievements of medicine. The immune system recognizes a virus or a bacterium as something alien and dangerous. When vaccinating against, for example, a virus, we send a warning to the infantry of the immune system – T-lifocytes - about the need to be alert. Subsequently, the immune system will quickly cope with such a virus without the knowledge of a person.
However, this approach could not be transformed into a sufficiently effective method of fighting cancer, since the tumor formed in the body coexists with the immune system in a state of conditional peace. Experts believe that such coexistence can be explained from an evolutionary point of view. Cancer develops more often in elderly people who have already passed on their genes to the next generation, and fighting it at this age is not a condition necessary for the survival of the species.
The tumor causes only a weak inflammatory reaction in the body, which is not considered by the immune system as a danger signal. Recognizing a tumor as a foreign object, T-lymphocytes do not see it as a source of danger and self-destruct. Under normal conditions, this mechanism protects the body from hyperreactivity of the immune system in relation to its own tissues. Moreover, malignant cells are able to release compounds that suppress the activity of surviving T-lymphocytes. Therefore, attempts to stimulate the patient's own weakened immune cells do not lead to the desired result.
Another disadvantage of modern antitumor vaccines is that they cause an immune response against proteins, high levels of expression of which are characteristic of tumor cells. However, these proteins are not foreign to the body and their abnormality lies only in the unusually high content in malignant cells.
The DNA of a cancer cell can contain hundreds of mutations. Protein products of mutated genes can be recognized by T-lymphocytes as foreign. However, it is almost impossible to find a mutation that would occur in all patients with a certain type of cancer. Theoretically, it is possible to simultaneously form many weak immune reactions against a large number of mutant proteins, however, this can lead the immune system out of control.
Immune response of a healthy bodyTo date, the standard cancer treatment protocols include two immunotherapeutic approaches, which are based on the use of immune reactions that have developed outside the patient's body.
One approach is to introduce therapeutic antibodies obtained by vaccinating animals with human cells. This is especially effective in the treatment of cancer of the lymphatic system, however, antibodies destroy healthy B-lymphocytes of the patient, which are an important component of the immune system.
The second approach is based on transplantation of healthy donors' bone marrow blood system to patients with oncological diseases. This procedure may be a person's only chance of survival, but it is very risky.
Unlike weakened patient cells, T-lymphocytes of a healthy donor instantly react to tumor cells, while their reactions are further enhanced by signals of inflammation caused by chemo and radiotherapy carried out to destroy the patient's own bone marrow. If the patient has gone through a difficult preparatory period for transplantation, it can lead to a complete cure, however, in about 75% of cases, donor immune cells begin to attack healthy cells of the recipient's skin, liver and intestines, which can lead to his death.
A new approachThe approach developed by Norwegian researchers avoids such side effects.
It is based on the use of T-lymphocytes from healthy donors, which are "trained" to recognize fragments of a protein that is part of only a certain type of cell. The resulting T-lymphocytes can destroy both healthy and pathological cells containing this protein, which normally does not cause a reaction from the immune system.
The training of T-lymphocytes is based on a fundamentally new approach, which consists in their incubation with autologous dendritic cells presenting on their surface a protein specific to the target tissue and a foreign histocompatibility antigen. (Histocompatibility antigens are expressed on the surface of almost all cells and are a kind of "personal signature" of the organism. It is the expression of these antigens that causes the development of immune rejection reactions during transplantation of donor organs and tissues.) This complex simultaneously stimulates T-lymphocytes and "trains" them against a certain type of cell.
When administered to a patient with, for example, prostate cancer or ovarian cancer, such cells will inevitably destroy not only the tumor, but also healthy cells of the appropriate type. However, life without these organs is better than death from a tumor.
Selectively acting T-lymphocytes are more effective than monoclonal antibodies against tumor proteins, since, unlike the latter, they recognize not only surface, but also intracellular proteins of target cells. Moreover, their use will allow solving one of the main problems of modern antitumor therapy – the recurrence of tumors. Selectively acting T-lymphocytes will destroy not only the primary tumor and metastases, but also all malignant cells circulating in the bloodstream.
The developers hope that over time, the new method will be adapted to treat all types of cancer of organs that are not critical to human life, including the prostate, ovaries and mammary glands, as well as organs that can be transplanted, such as bone marrow, kidneys and liver.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of Oslo:
Immune cells from healthy people pulverise cancer.
13.02.2012