Single domain antibodies from llama effectively and specifically block T cell ecto-ADP-ribosyltransferase ART2.2 in vivo

KOCH-NOLTE, F., REYELT, J., SCHÖßOW, B., SCHWARZ, N., SCHEUPLEIN, F., ROTHENBURG, S., HAAG, F., ALZOGARAY, V., CAUERHFF, A. AND GOLDBAUM, F. A.

FASEB JOURNAL

FEDERATION AMER SOC EXP BIOL

Año: 2007 vol. 21 p. 3490 - 3498

0892-6638

The purpose of our study was to developa tool for blocking the function of a specific leukocyteecto-enzyme in vivo. ART2.2 is a toxin-related ectoenzymethat transfers the ADP-ribose moiety from NADonto other cell surface proteins. ART2.2 induces T celldeath by activating the cytolytic P27 purinoceptor viaADP-ribosylation. Here, we report the generation ofART2.2-blocking single domain antibodies from animmunized llama. The variable domain of heavy-chainantibodies (VHH domain) represents the smallestknown antigen-binding unit generated by adaptive immuneresponses. Their long CDR3 endows VHH domainswith the extraordinary capacity to extend intoand block molecular clefts. Following intravenous injection,the ART2.2-specific VHH domains effectivelyshut off the enzymatic and cytotoxic activities ofART2.2 in lymphatic organs. This blockade was highlyspecific (blocking ART2.2 but not the related enzymesART1 or ART2.1), rapid (within 15 min after injection),and reversible (24 h after injection). Our findingsconstitute a proof of principle that opens up a newavenue for targeting leukocyte ecto-enzymes in vivo andthat can serve as a model also for developing newantidotes against ADP-ribosylating toxins.?Koch-Nolte, F., Reyelt, J., Scho¨ow, B., Schwarz, N., Scheuplein,F., Rothenburg, S., Haag, F., Alzogaray, V.,Cauerhff, A., and Goldbaum, F. A. Single domainantibodies from llama effectively and specifically blockT cell ecto-ADP-ribosyltransferase ART2.2 in vivo.