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Le Centre de Recherche en Cancérologie de Marseille fête ses 50 ans ! -

Jan 2008 Protein engineering, design & selection : PEDS

Isolation and characterization of anti-FcgammaRIII (CD16) llama single-domain antibodies that activate natural killer cells.


Behar G, Sibéril S, Groulet A, Chames P, Pugnière M, Boix C, Sautès-Fridman C, Teillaud JL, Baty D


FcgammaRIII (CD16) plays an important role in the anti-tumor effects of therapeutic antibodies. Bi-specific antibodies (bsAbs) targeting FcgammaRIII 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-FcgammaRIII sdAbs (C21 and C28) from a phage library generated from a llama immunized with FcgammaRIIIB extra-cellular domains. These sdAbs bind FcgammaRIIIA+ NK cells and FcgammaRIIIB+ polymorphonuclear cells, but not FcgammaRI+ or FcgammaRII+ cells, as detected by indirect immunofluorescence. Competition experiments showed that C21 and C28 sdAbs bind different FcgammaRIII 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 FcgammaRIII with a K(D) in the 10 and 80 nM range, respectively. Importantly, the engagement by both molecules of FcgammaRIIIA expressed by transfected Jurkat T cells or by NK cells derived from peripheral blood induced a strong IL-2 and IFN-gamma production, respectively. These anti-FcgammaRIII sdAbs represent versatile tools for generating bsAbs under various formats, able to recruit FcgammaRIII killer cells to target and destroy tumor cells.

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