This study looks at how a special type of pain relief, called Regional Anesthesia (RA), affects the body's reaction during painful episodes in people with Sickle Cell Disease. Sickle cell disease is a long-term illness where blood cells can get stuck and cause pain. During these painful times, known as vaso-occlusive crises, people usually need to drink fluids, get oxygen, and have pain relief. RA is a method that numbs a specific area of the body to quickly ease pain by blocking the nerves that send pain signals. Researchers believe RA might also help reduce inflammation (the body's reaction to injury or infection) during these crises.

While RA is known to help with pain and inflammation in other cases, its effects on inflammation for sickle cell patients haven't been proven yet. This study will measure changes in inflammation markers (signals in the body that tell us about inflammation) in patients with and without RA.

• Participants must be adults over 18 with a vaso-occlusive crisis.
• Pregnant women or those who've had recent blood transfusions cannot take part.
• French social security registration is required for participation.