With 23 approvals in the US and other countries and 4 approvals outside US, antibodies are now widely recognized as therapeutic molecules. The therapeutic and commercial successes met by rituximab,...

We have constructed deletion and point mutations within the Simian virus 40 (SV40) early promoter region which contains two tandemly repeated 21 bp sequences and a related 22 bp sequence (the "upstream" 21 bp repeat region). After transfection into permissive CV-1 cells and non-permissive mouse 3T3-4E cells, the effect of the mutations on early gene expression was studied by measuring T-antigen production, using indirect immunofluoresence. Our results demonstrate that the 21 bp repeat region, and in particular the six GC-rich motifs 5'-CCGCCC-3' which are repeated in this region constitute an important element of the SV40 early promoter. Surprisingly, we found that the requirement for the 21 bp repeat region for early gene expression was partially fulfilled even when it was in the inverted orientation.

FcγRIII (CD16) plays an important role in the anti-tumor effects of therapeutic antibodies. Bi-specific antibodies (bsAbs) targeting FcγRIII represent a powerful alternative to the recruitment of the receptor via the Fc fragment, but are not efficiently produced. Single-domain antibodies (sdAbs) endowed with many valuable structural features might help to bypass this problem. In the present work, we have isolated anti-FcγRIII sdAbs (C21 and C28) from a phage library generated from a llama immunized with FcγRIIIB extra-cellular domains. These sdAbs bind FcγRIIIA⁺ NK cells and FcγRIIIB⁺ polymorphonuclear cells, but not FcγRI⁺ or FcγRII⁺ cells, as detected by indirect immunofluorescence. Competition experiments showed that C21 and C28 sdAbs bind different FcγRIII epitopes, with C21 recognizing a linear and C28 a conformational epitope of the receptor. Surface plasmon resonance experiments showed that C21 and C28 sdAbs bind FcγRIII with a K_D in the 10 and 80 nM range, respectively. Importantly, the engagement by both molecules of FcγRIIIA expressed by transfected Jurkat T cells or by NK cells derived from peripheral blood induced a strong IL-2 and IFN-γ production, respectively. These anti-FcγRIII sdAbs represent versatile tools for generating bsAbs under various formats, able to recruit FcγRIII killer cells to target and destroy tumor cells.