Present status and future trends in molecular imaging of lymphocytes

Abstract

Immune system is emerging as a crucial protagonist in a huge variety of oncologic and non-oncologic conditions including response to vaccines and viral infections (such as SARS-CoV-2). The increasing knowledge of molecular biology underlying these diseases allowed the identification of specific targets and the possibility to use tailored therapies against them. Immunotherapies and vaccines are, indeed, more and more used nowadays for treating infections, cancer and autoimmune diseases and, therefore, there is the need to identify, quantify and monitor immune cell trafficking before and after treatment. This approach will provide crucial information for therapy decision-making. Imaging of B and T-lymphocytes trafficking by using tailored radiopharmaceuticals proved to be a successful nuclear medicine tool. In this review, we will provide an overview of the state of art and future trends for "in vivo" imaging of lymphocyte trafficking and homing by mean of specific receptor-tailored radiopharmaceuticals.

Figure 1

Schematic representation of targets for available receptor-tailored radiopharmaceuticals for imaging T-lymphocytes, NK cells and B-lymphocytes.

Figure 2

Axial sections of SPECT/MRI with ^99mTc-HYNIC IL2 showing increased pancreatic uptake in a patient with insulitis.

Figure 3

Anterior views of ^99mTc-rituximab in a patient with rheumatoid arthritis before (left panel) and after therapy with 16nlabeled rituximab (right panel).

Figure 4

Anterior views of ^99mTc-adalimumab (anti TNF-α) in a patient with rheumatoid arthritis showing increased expression of TNF-α in the hands.