Identification of antibody glycosylation structures that predict monoclonal antibody Fc-effector function

Objective: To determine monoclonal antibody (mAb) features that predict fragment crystalizable (Fc)-mediated effector functions against HIV. Design: Monoclonal antibodies, derived from Chinese hamster ovary cells or Epstein-Barr virus-immortalized mouse heteromyelomas, with specificity to key regions of the HIV envelope including gp120-V2, gp120-V3 loop, gp120-CD4(+) binding site, and gp41-specific antibodies, were functionally profiled to determine the relative contribution of the variable and constant domain features of the antibodies in driving robust Fc-effector functions. Methods: Each mAb was assayed for antibody-binding affinity to gp140(SF162), antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and for the ability to bind to Fc gamma RIIa, Fc gamma RIIb and Fc gamma RIIIa receptors. Antibody glycan profiles were determined by HPLC. Results: Neither the specificity nor the affinity of the mAbs determined the potency of Fc-effector function. Fc gamma RIIIa binding strongly predicted ADCC and decreased galactose content inversely correlated with ADCP, whereas N-glycolylneuraminic acidcontaining structures exhibited enhanced ADCP. Additionally, the bi-antenary glycan arm onto which galactose was added predicted enhanced binding to Fc gamma RIIIa and ADCC activity, independent of the specificity of the mAb. Conclusions: Our studies point to the specific Fc-glycan structures that can selectively promote Fc-effector functions independently of the antibody specificity. Furthermore, we demonstrated antibody glycan structures associated with enhanced ADCP activity, an emerging Fc-effector function that may aid in the control and clearance of HIV infection. (c) 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins