Introduction

1. Peptide labelling with fluor-19 and fluor-18 : OVA 323-339 and OVA 257-264 for thestudy of dendritic cells migration by PET Scan Laïque Salma [1], Lazarova Elena [2], Monclus Michel [1], Jacquemotte Françoise [3], Communi David [4], Flamand Véronique [2], Goldman Serge [1] [1] PET/Biomedical Cyclotron Unit, ULB, Hopital Erasme, Route de Lennik 808, 1070 Anderlecht, BELGIUM [2] Institute for Medical Immunology, ULB, Rue A. Bolland, B 6041 Gosselies, BELGIUM [3] Département des Substances Naturelles, Institut Meurice, 50 Avenue Emile Gryzon, 1070 Anderlecht, BELGIUM [4] I.R.I.B.H.M. , Bldg. C, ULB, Route de Lennik 808, 1070 Anderlecht, BELGIUM Introduction Dendritic cells (DC) migration is important to evaluate in immunotherapy protocoles. Ovalbumin323-339 and Ovalbumin257-264 are known to be recognised by MHC II complex of DC and to induce T lymphocytes proliferation (1). We propose to radiolabel these fragment with [18F]fluoroethyl moiety to image by PET pulsed DC injected into mice. We here present the biological results of the non radioactive tracer, N-[19F]fluoro-ethyl-OVA323-339 (FEthOVA323-339) and our preliminary tests of radiolabelling on OVA257-264. OVA 323-339 : NH2– Ile – Ser – Gln – Ala – Val – His – Ala – Ala – His – Ala – Glu – Ile – Asn – Glu – Ala – Gly – Arg – OH OVA 257-264 : NH2 – Ser – Ile – Ile – Asn – Phe – Glu – Lys – Leu – OH Non radioactive peptides Biology Peptide synthesis : on solid phase FEtOTs synthesis (2) Principle of SPPS In vitro comparaison between OVA323-339 and FEtOVA323-339, measured by 3H-thymidin incorporation after 48h MLR Coupling reaction Conclusions: FEthOVA323-339 holds antigenic properties of OVA323-339. The F-18-labeled form of this peptide should therefore be evaluated for PET imaging of pulsed-DC migration. Radioactive peptides QMA 18F-/K2.2.2./K2CO3 18FEtOTs (+18F- + 1,2-ditosyloxyethane) 1,2-ditosyloxyethane purification protected OVA257-264 18FEtOTs + 18FEtOTs basic conditions protected OVA257-264NH-CH2-CH2-18F (+ 18FEtOTs) purification TFA/TIS/thioanisole protected OVA257-264NH-CH2-CH2-18F OVA257-264NH-CH2-CH2-18F Validation by analyitical HPLC LC-MS scavengers suppression preparative HPLC OVA257-264NH-CH2-CH2-18F References Protected peptide : OVA 257-264 : NH2 – Ser – Ile – Ile – Asn(Ttr)– Phe – Glu(OtBu) – Lys(Boc)– Leu – OHX : protecting groups (1)Wilson AA, Dasilva JN, Houle S. Synthesis of two radiofluorinated cocaine analogues using distilled 2-[18F]fluoroethylbromide. Appl. Radiat. Isot. 46(8):765-770,1995 (2) Roberston JM, Jensen PE, Evavold BD. DO11.10 and OT.II T cells recognise a C-terminal Ovalbumin 323-339 epitope. J. Immunol. 164:4706-4712, 2000 Contacts •  : salma.laique@ulb.ac.be • : 0032-2-555.47.11