A patient with rheumatoid arthritis is prescribed methotrexate. Which of the following is the primary mechanism of action of methotrexate in autoimmune diseases? It reduces the number of activated T lymphocytes. It blocks tumor necrosis factor-alpha (TNF-alpha). It inhibits the synthesis of purines and pyrimidines, thus suppressing immune cell proliferation. It inhibits cyclooxygenase-1 and 2 (COX-1, COX-2).
Answer (1)
It inhibits the synthesis of purines and pyrimidines, thus suppressing immune cell proliferation. Methotrexate works by blocking an enzyme involved in DNA synthesis, which is necessary for immune cells to multiply. In autoimmune diseases like rheumatoid arthritis, this helps by slowing down the overactive immune response that causes joint inflammation and pain.
