Mechanism of action of tacrolimus (FK-506) is:
a) Inhibits CD3 receptor.
b) Complement-mediated cytolysis of T lymphocytes.
c) Substitution for patient's deficient immunoglobulins.
d) Inhibits calcineurin.
T cell function
There are many steps involved in T cell activation and differentiation so that they can carry out their roles in cell-mediated immunity. All of these steps are potential targets for drug development.
Answer and Explanation: 1
Calcineurin is a protein phosphatase that is part of the cell signaling pathway to activate T cells. Tacrolimus (FK-506) binds to the protein FKBP12 (FK-506-binding protein), and this complex inhibits the activity of calcineurin, making d) Inhibits calcineurin the correct answer.
Inhibiting the CD3 co-receptor would also prevent T cell activation, but is not the mechanism of tacrolimus. Tacrolimus also plays no direct role in complement-mediated lysis and is not an immunoglobulin, so it can't substitute for immunoglobulin deficiencies.
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fromChapter 43 / Lesson 4
Our immune systems are pretty good, but sometimes pathogens can sneak in and infect living cells. Luckily, we've got a back up system. Let's explore cell-mediated response and see how this protects our bodies from infections that may otherwise go untreated.