BACKGROUND:  Positron emission tomography (PET) is a medical imaging technique that scans the body, producing a three-dimensional image or map of the body's biological processes. In order to conduct the PET scan, subjects receive an intravenous injection of a minute amount of a metabolically active molecule labeled with a radioisotope that will image the biological process of interest. Current existing PET-probes, such as FDG, do not have the specificity to image immune activation responses. There is a need for novel PET probes that are sensitive and specific for the monitoring of immune activation.

INNOVATION:  Researchers at UCLA have developed novel positron emission tomography (PET) probes to image and monitor immune activation. Various chemical compounds were screened to identify ones that accumulate in activated lymphocytes, and then labeled with the positron-emitting radioisotope F-18 to generate PET probes. These PET probes specifically target proteins expressed during activation of T lymphocytes and of other immune cells such as B cells, macrophages and dendritic cells. In vivo imaging of activated immune cells was then demonstrated.

POTENTIAL APPLICATIONS 

• Non-invasive, whole body PET-based monitoring of immune activation, potentially in cancer, immunotherapy, autoimmune disorders, infectious diseases and vaccine testing

ADVANTAGES

• Small molecule PET probes specifically target proteins expressed during the activation of immune cells such as T lymphocytes and during cell proliferation
• Increased specificity compared to existing approaches, such as FDG-PET

DEVELOPMENT-TO-DATE:  UCLA researchers have identified target genes that are upregulated during T cell activation and are using proteins expressed from these genes to design chemical structures for PET probes. Investigators have been successful in synthesizing one of the PET probes and testing it in mice that underwent systemic immune activation. Investigators also tested this probe for imaging certain hematologic malignancies and solid tumors.

Related Papers (Selected)

• Molecular imaging of lymphoid organs and immune activation by positron emission tomography with a new [18F]-labeled 2'-deoxycytidine analog. Nat Med. 2008 Jul;14(7):783-8. Epub 2008 Jun 8. [more]