Development of radiolabelled white cell scanning

Area of Science:

• Nuclear Medicine
• Immunology
• Gastroenterology

Background:

• White blood cell imaging for inflammation detection began in 1976 using gamma-emitting radioisotopes.
• Early methods involved whole-body granulocyte distribution studies.
• Cell activation during labeling was a challenge, leading to non-physiological lung uptake.

Purpose of the Study:

• To review the evolution and current state of radiolabelled white blood cell imaging for inflammation.
• To compare different radiolabelling techniques and their clinical applications.
• To highlight the advantages of radiolabelled leucocytes for localizing inflammation.

Main Methods:

• Utilizing gamma-emitting radioisotopes (e.g., 111In, 99mTc) to label white blood cells.
• Employing chelates like tropolone and lipophilic complexes (e.g., HMPAO) to label cells.
• Assessing whole-body distribution, splenic activity, and fecal excretion of labeled cells.
• Investigating newer experimental approaches like labeled immunoglobulins and antibodies.

Main Results:

• Normal subjects show uptake in bone marrow, liver, and spleen.
• Liver activity indicates cell damage, while splenic activity reflects leukocyte mobilization to inflammation sites.
• 111In-labeled granulocytes and whole-body retention were used to assess Crohn's disease activity.
• 99mTc-HMPAO offered advantages over 111In for inflamed bowel imaging, emphasizing early imaging.

Conclusions:

• Radiolabelled leucocytes are the best current technique for localizing inflammation.
• Technological advancements have improved cell labeling efficiency and reduced artifacts.
• Ongoing research explores novel targeting strategies for inflammation imaging.