Hematopoiesis in MBL and CLL Versus Healthy Age-Matched Control Subjects

This research study compares blood stem cell production in people with chronic lymphocytic leukemia (CLL) or a related pre-leukemia condition called monoclonal B-cell lymphocytosis (MBL) against healthy people of similar age. It aims to understand how these conditions affect the blood-forming system. **You may be eligible if...** - You have a confirmed diagnosis of CLL (whether untreated, currently in treatment, or previously treated) - You have been diagnosed with MBL (a pre-cancerous condition) - You are a healthy adult over 40 years old willing to serve as a comparison volunteer **You may NOT be eligible if...** - You are under 40 years old - You are a healthy volunteer who has been diagnosed with CLL or MBL Talk to your doctor to see if this trial is right for you.