Human monocytes (Mo) and monocyte-derived macroresponse. To overcome this limitation we have developed phages (MdM) are major effectors in host defense systems a gene transfer protocol with IFN-␥ cDNA and polyethyleniagainst cancer. Their antitumoral activity is dependent mine so as to obtain an efficient, long-lasting autocrine upon two processes: recruitment and activation. One of the cytocidal activation in transfected human Mo/MdM. We most powerful activators for these cells is recombinant show, by clonogenic assays, that efficient transfection and human IFN-␥ (rhIFN-␥). However, when the potential of tumoricidal activity can be obtained by this method in activated rhIFN-␥ was evaluated in clinical trials by ex vivo human monocyte populations. Although the proposed adoptive cellular immunotherapy protocols, the major probmodel must be improved before clinical use, IFN-␥ produclem was the short duration of ex vivo activation by rhIFN-␥.ing monocytes have potential for adoptive immunotherapy. Thus repeated injections were required to obtain a clinical

The human leucine-rich repeat-containing protein 15 (LRRC15) is a membrane protein identified as a marker of CAF (cancer-associated fibroblast) cells whose overexpression is positively correlated with cancer grade and outcome. Nuclear molecular imaging (i.e., SPECT and PET) to track LRRC15 expression could be very useful in guiding further therapeutic strategies. In this study, we developed an ScFv mouse phage-display library to obtain small fragment antibodies against human LRRC15 for molecular imaging purposes. Mice were immunized with recombinant human LRRC15 (hLRRC15), and lymph node cells were harvested for ScFv (single-chain variable fragment) phage-display analysis. The built library was used for panning on cell lines with constitutive or induced expression after transfection. The choice of best candidates was performed by screening various other cell lines, using flow cytometry. The selected candidates were reformatted into Cys-ScFv or Cys-diabody by addition of cysteine, and cloned in mammalian expression vectors to obtain batches of small fragments that were further used in site-specific radiolabeling tests. The obtained library was 1.2 × 107 cfu/µg with an insertion rate >95%. The two panning rounds performed on cells permittedenrichment of 2 × 10−3. Screening with flow cytometry allowed us to identify 28 specific hLRRC15 candidates. Among these, two also recognized murine LRCC15 and were reformatted into Cys-ScFv and Cys-diabody. They were expressed transiently in a mammalian system to obtain 1.0 to 4.5 mg of Cys fragments ready for bioconjugation and radiolabeling. Thus, in this paper, we demonstrate the relevance of the phage-display ScFv library approach for the fast-track development of small antibodies for imaging and/or immunotherapy purposes.

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