Novel Tools for Functional Analysis of CD11c: Activation‐Specific, Activation‐Independent, and Activating Antibodies

Abstract

Functions and binding properties of four CD11c‐specific mAbs are described here. The mAb 496B stimulated, while 496K inhibited ligand binding of CD11c. The stimulatory mAb, 496B, as well as the inhibitory mAbs BU15 and 496 K appear to act allosterically, as they do not bind the CD11c I domain. The mAb 3.9 bound preferentially to activated forms of CD11c and the binding was divalent cation dependent. CD11c binding to 3.9 recapitulates many of the integrin‐ligand interactions. Our data suggest that 3.9 is a competitive antagonist, BU15 and 496K are allosteric antagonists, and 496B is an allosteric agonist of CD11c. These mAbs provide a set of tools to study the functions of the dendritic cell marker, CD11c.

Keywords:

• CD11c
• Ligand mimetic
• I domain
• Antibodies
• Agonistic
• Allosteric

Acknowledgments

We thank Padma Ravikumar and Lee Adams for help with the generation of JY[hCD11c] cells, CD11c I domain mutants, CD11a/CD18 and CD11c/CD18 expression constructs, and Byron Knellor for the purification of CD11c proteins. We also thank Tony DeMaggio for help with the preparation of the Figures. Expert assistance of Ana Edwards, Scott Hussell, and Rick Jasman in the generation of 496 series of anti‐human CD11c mAbs is specially appreciated. We are grateful to David Crowe and Vince Florio for suggestions and critical reading of the manuscript.