Alemtuzumab is antibody against
**Core Concept**
Alemtuzumab is a monoclonal antibody used in the treatment of multiple sclerosis and chronic lymphocytic leukemia. It targets a specific protein on the surface of immune cells, leading to their destruction. This mechanism of action is based on the concept of immunomodulation, where an antibody is used to modulate the immune response.
**Why the Correct Answer is Right**
Alemtuzumab is an antibody against CD52, a protein present on the surface of mature lymphocytes and monocytes. The binding of alemtuzumab to CD52 leads to the activation of complement and the induction of apoptosis in these cells. This results in a decrease in the number of circulating lymphocytes, which can help to reduce inflammation in multiple sclerosis and inhibit the proliferation of cancer cells in chronic lymphocytic leukemia.
**Why Each Wrong Option is Incorrect**
**Option A:** Alemtuzumab is not an antibody against CD20, which is a different protein targeted by rituximab, another monoclonal antibody used in the treatment of lymphomas and autoimmune diseases.
**Option B:** Alemtuzumab is not an antibody against CD19, which is a protein present on the surface of B cells and is targeted by other monoclonal antibodies, such as blinatumomab.
**Option C:** Alemtuzumab is not an antibody against CD3, which is a protein present on the surface of T cells and is targeted by other monoclonal antibodies, such as alefacept.
**Clinical Pearl / High-Yield Fact**
Alemtuzumab is associated with a risk of severe infusion reactions, including anaphylaxis, and patients should be closely monitored during administration. Additionally, alemtuzumab can increase the risk of secondary autoimmune disorders, such as thyroiditis and Guillain-Barré syndrome.
**Correct Answer:** C. CD52