Immunosuppression, Induction Therapy

Now that we have an understanding of how the immune system works, I will begin to discuss the main therapies used to prevent it from doing its job. Medicines used very soon after the surgery to suppress the initial immune response fall into the category of induction therapy. Those used to prevent rejection in the long term fall into the category of maintenance therapy. The goal of induction therapy is reduce the risk of acute rejection of the graft and as of 2015 80% of kidney transplant centers in the US use induction agents as part of their immunosuppression protocols. Induction agents are generally used because of their ability to affect several of the most critically important cells (T-Cells and B-Cells) and to quickly and severely reduce their effectiveness. It is for this reason that doctors will often put off a patient’s transplant even if they have a minor infection. This first wave of immunosuppressants can make even a small infection proliferate which may ultimately lead to death. The most commonly used agents are rATG (which is actually synthesized from rabbits!), Basiliximab, and Alemtuzumab. Each stops the naive T-Cell (T-Cell before it is presented with a particular antigen to attack) from becoming active in different ways, but one thing they all have in common is that they do not interfere with the patient’s recovery from the surgery. The most common maintenance agents (CNIs) have the side effect of constricting the blood vessels, which can prolong the amount of time before a wound (such as surgical cuts) heals. Alongside the induction agents transplant patients are given high-doses of steroids. The agents are generally taken only once, immediately after the procedure, however, the medicine has a long half-life (time it takes for it for half the medicine to be filtered out) and may stay in the body, working, for several weeks. Below is a picture of which part in T-Cell differentiation each medicine affects (I thought it looked cool).