The Immune System

The immune system is able to distinguish foreign invaders within the body. An antigen is a chemical from a virus, bacteria, fungus, blood or a transplanted organ, that is recognized as foreign by the immune system. When the body identifies an antigen it produces antibodies to fight that specific antigen. Antibodies are the body’s first lines of defense against infection. In addition, antibodies also provide the body with a memory of exposures to previous antigens. For example, once your child has had chicken pox, the antibodies in the immune system will prevent him or her from getting this virus again.

Lymphocytes are vital to the proper functioning of the immune system. They are white blood cells that control your child’s response to antigens. There are two types of lymphocytes called B-cells and T-cells. B-cells produce antibodies and T-cells are responsible for rejection of transplanted tissue. Lymphocytes communicate with other cells in the immune by releasing chemicals called lymphokines. These chemicals signal or recruit other immune cells to join the battle against foreign invaders. Antigens on the surface of transplanted organs are released and recognized by the recipient’s immune system as foreign. Therefore, the recipient mobilizes a defensive response quickly and efficiently against the transplanted organ. This process is called rejection.

The success of the lung transplant depends on the ability of your child’s body to accept the new lungs. Therefore, the body’s natural ability to react negatively to the transplanted organ (rejection) must be suppressed. Two different mechanisms are used to prevent rejection of transplanted lungs. First, prior to transplantation, blood of the donor and recipient are matched to minimize the number of foreign antigens that the recipient receives. The second approach uses powerful immunosuppressant medications to alter the immune system response to the transplanted lung. The medications your child will take are used to control or stop the body’s natural response against foreign substances. However, using these medications will make your child more susceptible to infections. Finding the right medication dosage for your child is a balancing act between the conflicting needs of preventing rejection and of avoiding infection. Your child will need to take these medications for the rest of his or her life.