INFLIXIMAB (systemic) is used in
**Core Concept**
Infliximab is a monoclonal antibody that targets tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine involved in various autoimmune and inflammatory conditions. By binding to TNF-alpha, infliximab inhibits its interaction with its receptor, thereby reducing inflammation and immune system activation.
**Why the Correct Answer is Right**
Infliximab is used to treat several chronic inflammatory conditions, including rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and Crohn's disease. The mechanism of action of infliximab involves the binding of TNF-alpha to its receptor on the surface of immune cells, which triggers a cascade of signaling events leading to inflammation. By blocking this interaction, infliximab reduces the production of pro-inflammatory cytokines and mediators, resulting in decreased inflammation and clinical improvement.
**Why Each Wrong Option is Incorrect**
**Option A:** While infliximab is used to treat autoimmune conditions, it is not typically used for treating infections, as it can suppress the immune system and increase the risk of infections.
**Option B:** Infliximab is not used for treating conditions that involve an overactive immune response, such as sepsis, as it can worsen the condition by suppressing the immune response.
**Option C:** Infliximab is not used for treating conditions that involve an underactive immune response, such as immunodeficiency disorders, as it can suppress the immune system further.
**Clinical Pearl / High-Yield Fact**
It's essential to note that infliximab can increase the risk of infections, particularly those caused by opportunistic pathogens, such as tuberculosis and histoplasmosis. Therefore, patients receiving infliximab should be closely monitored for signs of infection and have regular tuberculosis screening.
**Correct Answer:** D. Crohn's disease