Immunotherapy is the "treatment of disease by inducing, enhancing, or suppressing an immune response". Immunotherapies designed to elicit or amplify an immune response are classified as activation immunotherapies, while immunotherapies that reduce or suppress are classified as suppression immunotherapies.
In recent years, immunotherapy has become of great interest to researchers, clinicians and pharmaceutical companies, particularly in its promise to treat various forms of cancer.
Immunomodulatory regimens often have fewer side effects than existing drugs, including less potential for creating resistance when treating microbial disease.
Cell-based immunotherapies are effective for some cancers. Immune effector cells such as lymphocytes, macrophages, dendritic cells, natural killer cells (NK Cell), cytotoxic T lymphocytes (CTL), etc., work together to defend the body against cancer by targeting abnormal antigens expressed on the surface of tumor cells.
Therapies such as granulocyte colony-stimulating factor (G-CSF), interferons, imiquimod and cellular membrane fractions from bacteria are licensed for medical use. Others including IL-2, IL-7, IL-12, various chemokines, synthetic cytosine phosphate-guanosine (CpG) oligodeoxynucleotides and glucans are involved in clinical and preclinical studies.
Video Immunotherapy
Immunomodulators
Immunomodulators are the active agents of immunotherapy. They are a diverse array of recombinant, synthetic, and natural preparations.
Maps Immunotherapy
Activation immunotherapies
Cancer
Cancer immunotherapy attempts to stimulate the immune system to destroy tumors. A variety of strategies are in use or are undergoing research and testing. Randomized controlled studies in different cancers resulting in significant increase in survival and disease free period have been reported and its efficacy is enhanced by 20-30% when cell-based immunotherapy is combined with conventional treatment methods.
The extraction of G-CSF lymphocytes from the blood and expanding in vitro against a tumour antigen before reinjecting the cells with appropriate stimulatory cytokines. The cells then destroy the tumor cells that express the antigen.
BCG immunotherapy for early stage (non-invasive) bladder cancer instills attenuated live bacteria into the bladder and is effective in preventing recurrence in up to two thirds of cases.
Topical immunotherapy utilizes an immune enhancement cream (imiquimod) which produces interferon, causing the recipient's killer T cells to destroy warts, actinic keratoses, basal cell cancer, vaginal intraepithelial neoplasia, squamous cell cancer, cutaneous lymphoma, and superficial malignant melanoma.
Injection immunotherapy ("intralesional" or "intratumoral") uses mumps, candida, the HPV vaccine or trichophytin antigen injections to treat warts (HPV induced tumors).
Adoptive cell transfer has been tested on lung and other cancers.
Dendritic cell-based pump-priming
Dendritic cells can be stimulated to activate a cytotoxic response towards an antigen. Dendritic cells, a type of antigen presenting cell, are harvested from the person needing the immunotherapy. These cells are then either pulsed with an antigen or tumor lysate or transfected with a viral vector, causing them to display the antigen. Upon transfusion into the person, these activated cells present the antigen to the effector lymphocytes (CD4+ helper T cells, cytotoxic CD8+ T cells and B cells). This initiates a cytotoxic response against tumor cells expressing the antigen (against which the adaptive response has now been primed). The cancer vaccine Sipuleucel-T is one example of this approach.
T-cell adoptive transfer
Adoptive cell transfer in vitro cultivates autologous, extracted T cells for later transfusion. The T cells may already target tumor cells. Alternatively, they may be genetically engineered to do so. These T cells, referred to as tumor-infiltrating lymphocytes (TIL), are multiplied using high concentrations of Interleukin-2, anti-CD3 and allo-reactive feeder cells. These T cells are then transferred back into the person along with administration of IL-2 to further boost their anti-cancer activity.
Before reinfusion, lymphodepletion of the recipient is required to eliminate regulatory T cells as well as unmodified, endogenous lymphocytes that compete with the transferred cells for homeostatic cytokines. Lymphodepletion can be achieved by total body irradiation. Transferred cells multiplied in vivo and persisted in peripheral blood in many people, sometimes representing levels of 75% of all CD8+ T cells at 6-12 months after infusion. As of 2012, clinical trials for metastatic melanoma were ongoing at multiple sites.
Immune enhancement therapy
Autologous immune enhancement therapy use a person's own peripheral blood-derived natural killer cells, cytotoxic T lymphocytes and other relevant immune cells are expanded in vitro and then reinfused. The therapy has been tested against Hepatitis C, Chronic fatigue syndrome and HHV6 infection.
Genetically engineered T cells
Genetically engineered T cells are created by harvesting T cells and then infecting the T cells with a retrovirus that contains a copy of a T cell receptor (TCR) gene that is specialised to recognise tumour antigens. The virus integrates the receptor into the T cells' genome. The cells are expanded non-specifically and/or stimulated. The cells are then reinfused and produce an immune response against the tumour cells. The technique has been tested on refractory stage IV metastatic melanomas and advanced skin cancer
Immune recovery
Another potential use of immunotherapy is to restore the immune system of people with immune deficiencies. Cytokines, Interleukin-7 and Interleukin-2 have been tested in clinical trials.
Vaccination
Antimicrobial immunotherapy, which includes vaccination, involves activating the immune system to respond to an infectious agent.
Suppression immunotherapies
Immune suppression dampens an abnormal immune response in autoimmune diseases or reduces a normal immune response to prevent rejection of transplanted organs or cells.
Immunosuppressive drugs
Immunosuppressive drugs help manage organ transplantation and autoimmune disease. Immune responses depend on lymphocyte proliferation. Cytostatic drugs are immunosuppressive. Glucocorticoids are somewhat more specific inhibitors of lymphocyte activation, whereas inhibitors of immunophilins more specifically target T lymphocyte activation. Immunosuppressive antibodies target steps in the immune response. Other drugs modulate immune responses.
Immune tolerance
The body naturally does not launch an immune system attack on its own tissues. Immune tolerance therapies seek to reset the immune system so that the body stops mistakenly attacking its own organs or cells in autoimmune disease or accepts foreign tissue in organ transplantation. Creating immunity reduces or eliminates the need for lifelong immunosuppression and attendant side effects. It has been tested on transplantations, and type 1 diabetes or other autoimmune disorders.
Allergies
Immunotherapy is used to treat allergies. While allergy treatments (such as antihistamines or corticosteroids) treat allergic symptoms, immunotherapy can reduce sensitivity to allergens, lessening its severity.
Immunotherapy may produce long-term benefits. Immunotherapy is partly effective in some people and ineffective in others, but it offers allergy sufferers a chance to reduce or stop their symptoms.
The therapy is indicated for people who are extremely allergic or who cannot avoid specific allergens. Immunotherapy is generally not indicated for food or medicinal allergies. This therapy is particularly useful for people with allergic rhinitis or asthma.
The first dose contain tiny amounts of the allergen or antigen. Dosages increase over time, as the person becomes desensitized. This technique has been tested on infants to prevent peanut allergies.
Helminthic therapies
Whipworm ova (Trichuris suis) and Hookworm (Necator americanus) have been tested for immunological diseases and allergies. Helminthic therapy has been investigated as a treatment for relapsing remitting multiple sclerosis Crohn's, allergies and asthma. The mechanism of how the helminths modulate the immune response, is unknown. Hypothesized mechanisms include re-polarisation of the Th1 / Th2 response and modulation of dendritic cell function. The helminths down regulate the pro-inflammatory Th1 cytokines, Interleukin-12 (IL-12), Interferon-Gamma (IFN-?) and Tumour Necrosis Factor-Alpha (TNF-?), while promoting the production of regulatory Th2 cytokines such as IL-10, IL-4, IL-5 and IL-13.
Co-evolution with helminths has shaped some of the genes associated with Interleukin expression and immunological disorders, such Crohn's, ulcerative colitis and celiac disease. Helminth's relationship to humans as hosts should be classified as mutualistic or symbiotic.
See also
- Biological response modifiers
- Interleukin-2 immunotherapy
- Microtransplantation
References
External links
- Langreth, Robert (12 February 2009). "Cancer Miracles". Forbes.
- International Society for Biological Therapy of Cancer
- Cancer Research Institute Annual International Cancer Immunotherapy Symposia Series
Source of article : Wikipedia
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