title: Immuno-PET of Murine T Cell Reconstitution Postadoptive Stem Cell Transplantation Using Anti-CD4 and Anti-CD8 Cys-Diabodies.
abstract: The proliferation and trafficking of T lymphocytes in immune responses are crucial events in determining inflammatory responses. To study whole-body T lymphocyte dynamics noninvasively in vivo, we generated anti-CD4 and -CD8 cys-diabodies (cDbs) derived from the parental antibody hybridomas GK1.5 and 2.43, respectively, for (89)Zr-immuno-PET detection of helper and cytotoxic T cell populations.
  
  
  METHODS
  Anti-CD4 and -CD8 cDbs were engineered, produced via mammalian expression, purified using immobilized metal affinity chromatography, and characterized for T cell binding. The cDbs were site-specifically conjugated to maleimide-desferrioxamine for (89)Zr radiolabeling and subsequent small-animal PET/CT acquisition and ex vivo biodistribution in both wild-type mice and a model of hematopoietic stem cell (HSC) transplantation.
  
  
  RESULTS
  Immuno-PET and biodistribution studies demonstrate targeting and visualization of CD4 and CD8 T cell populations in vivo in the spleen and lymph nodes of wild-type mice, with specificity confirmed through in vivo blocking and depletion studies. Subsequently, a murine model of HSC transplantation demonstrated successful in vivo detection of T cell repopulation at 2, 4, and 8 wk after HSC transplantation using the (89)Zr-radiolabeled anti-CD4 and -CD8 cDbs.
  
  
  CONCLUSIONS
  These newly developed anti-CD4 and -CD8 immuno-PET reagents represent a powerful resource to monitor T cell expansion, localization, and novel engraftment protocols. Future potential applications of T cell-targeted immuno-PET include monitoring immune cell subsets in response to immunotherapy, autoimmunity, and lymphoproliferative disorders, contributing overall to preclinical immune cell monitoring.
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California rtavare@mednet.ucla.edu awu@mednet.ucla.edu.
authors.forename: Richard
authors.initials: R
authors.lastname: Tavaré
authors.affiliation: Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Melissa N
authors.initials: MN
authors.lastname: McCracken
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Kirstin A
authors.initials: KA
authors.lastname: Zettlitz
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Felix B
authors.initials: FB
authors.lastname: Salazar
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Tove
authors.initials: T
authors.lastname: Olafsen
authors.affiliation: Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California Howard Hughes Medical Institute at UCLA, Los Angeles, California Department of Microbiology, Immunology and Molecular Genetics at UCLA, Los Angeles, California; and Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA, Los Angeles, California.
authors.forename: Owen N
authors.initials: ON
authors.lastname: Witte
authors.affiliation: Crump Institute for Molecular Imaging, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California rtavare@mednet.ucla.edu awu@mednet.ucla.edu.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wu
mesh_terms: D000818:Animals; D015704:CD4 Antigens / Q000378:metabolism*; D016827:CD8 Antigens / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology; D049109:Cell Proliferation; D002846:Chromatography, Affinity; D018380:Hematopoietic Stem Cell Transplantation; D007167:Immunotherapy / Q000379:methods; D008301:Maleimides / Q000737:chemistry*; D051379:Mice; D008810:Mice, Inbred C57BL; D049268:Positron-Emission Tomography / Q000379:methods*; D057127:Single-Chain Antibodies; D013601:T-Lymphocytes / Q000166:cytology; D013997:Time Factors; D014018:Tissue Distribution; D015040:Zirconium / Q000737:chemistry
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D008301:Maleimides; D057127:Single-Chain Antibodies; C043592:maleimide; D015040:Zirconium
keywords: 89Zr; CD4+ and CD8+ T cells; antibody fragments; hematopoietic stem cell transplantation; immuno-PET