Anti-thymocyte globulin (ATG) is a type of immunotherapy used in medical treatments. It works by influencing the body’s immune system to manage certain responses, especially when suppression or modulation is needed.
Understanding ATG Treatment
Anti-thymocyte Globulin (ATG) is a medication derived from antibodies. It functions as an immunosuppressant. The antibodies are sourced from animals, such as horses or rabbits, that have been immunized with human thymocytes or T-lymphoblast cell lines.
These animals produce antibodies that recognize and target human immune cells. These antibodies are then collected, purified, and formulated into the ATG medication. This allows ATG to precisely target specific immune cells, helping to regulate immune responses.
How ATG Works
ATG modulates the immune system by targeting and depleting T-lymphocytes, commonly known as T-cells. T-cells are a type of white blood cell that plays a significant role in the body’s immune response, including recognizing and attacking foreign invaders or transplanted tissues. ATG binds to various markers on the surface of T-cells, such as CD2, CD3, CD4, and CD8, leading to their destruction.
This depletion of T-cells can occur through several mechanisms. By reducing the number of active T-cells, ATG helps prevent or lessen unwanted immune reactions, such as organ rejection. The suppression of T-cells is temporary, allowing the immune system to recover over time.
Medical Conditions Treated with ATG
ATG treatment is used for conditions where modulating the immune system offers therapeutic benefits. One of its main applications is in organ transplantation, particularly to prevent or treat acute rejection in recipients of kidney, heart, and liver transplants. By suppressing the immune system, ATG helps the recipient’s body accept the new organ.
ATG also serves as a treatment for severe aplastic anemia, a condition where the bone marrow fails to produce enough blood cells. In this context, ATG works by suppressing the immune cells that may be attacking the patient’s own bone marrow stem cells, allowing the bone marrow to recover. It is also used to prevent or treat graft-versus-host disease (GVHD) following hematopoietic stem cell transplantation.
What to Expect During and After ATG Treatment
ATG is administered intravenously, typically through a central line in a hospital setting. The infusion usually takes several hours, ranging from 4 to 24 hours per dose, and may be given daily for several days, such as a 4-day course for aplastic anemia or 7 to 14 days for organ transplant rejection. Close monitoring is maintained throughout the infusion to observe for any immediate reactions.
Patients receive pre-medications, such as corticosteroids, antihistamines, and acetaminophen, before the ATG infusion to manage potential side effects. Common short-term side effects include fever, chills, rash, and changes in blood pressure, which may occur during or shortly after the infusion. Some patients may experience “cytokine release syndrome,” a reaction characterized by symptoms like high fever, chills, rapid heart rate, and possibly respiratory distress or low blood pressure. These reactions are managed by adjusting the infusion rate and continuing pre-medications.
After completing ATG treatment, patients face an increased risk of infection due to the temporary suppression of their immune system. Ongoing monitoring through regular blood tests and follow-up appointments is necessary to track blood counts and immune recovery. Patients are advised to take precautions to prevent infections, such as frequent hand washing, avoiding crowded places, and staying away from individuals who are sick. Adherence to prescribed medications, including other immunosuppressants and prophylactic antibiotics, is important for long-term management.