Early identification of antigen-specific immune responses in vivo by [18F]-labeled 3'-fluoro-3'-deoxy-thymidine ([18F]FLT) PET imaging.
Current biomarkers are unable to adequately predict vaccine-induced immune protection in humans with infectious disease or cancer. However, timely and adequate assessment of antigen-specific immune responses is critical for successful vaccine development. Therefore, we have developed a method for the direct assessment of immune responses in vivo in a clinical setting. Melanoma patients with lymph node (LN) metastases received dendritic cell (DC) vaccine therapy, injected intranodally, followed by [(18)F]-labeled 3'-fluoro-3'-deoxy-thymidine ([(18)F]FLT) PET at varying time points after vaccination. Control LNs received saline or DCs without antigen. De novo immune responses were readily visualized in treated LNs early after the prime vaccination, and these signals persisted for up to 3 wk. This selective [(18)F]FLT uptake was markedly absent in control LNs, although tracer uptake in treated LNs increased profoundly with as little as 4.5 × 10(5) DCs. Immunohistochemical staining confirmed injected DC dispersion to T-cell areas and resultant activation of CD4(+) and CD8(+) T cells. The level of LN tracer uptake significantly correlates to the level of circulating antigen-specific IgG antibodies and antigen-specific proliferation of T cells in peripheral blood. Furthermore, this correlation was not observed with [(18)F]-labeled fluoro-2-deoxy-2-D-glucose. Therefore, [(18)F]FLT PET offers a sensitive tool to study the kinetics, localization, and involvement of lymphocyte subsets in response to vaccination. This technique allows for early discrimination of responding from nonresponding patients in anti-cancer vaccination and aid physicians in individualized decisionmaking.
Department of Tumor Immunology, Radboud University Nijmegen Medical Centre, 6500 HB, Nijmegen, The Netherlands.
Erik H J G
EH
Aarntzen
Mangala
M
Srinivas
Johannes H W
JH
De Wilt
Joannes F M
JF
Jacobs
W Joost
WJ
Lesterhuis
Albert D
AD
Windhorst
Esther G
EG
Troost
Johannes J
JJ
Bonenkamp
Michelle M
MM
van Rossum
Willeke A M
WA
Blokx
Roel D
RD
Mus
Otto C
OC
Boerman
Cornelis J A
CJ
Punt
Carl G
CG
Figdor
Wim J G
WJ
Oyen
I Jolanda M
IJ
de Vries
D000951:Antigens, Neoplasm / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019496:Cancer Vaccines / Q000008:administration & dosage* / Q000276:immunology; D015224:Dideoxynucleosides; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging / Q000276:immunology; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000276:immunology / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals
D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D015224:Dideoxynucleosides; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; C076821:3',3'-difluoro-3'-deoxythymidine