A.W. Chung, M. Crispin, L. Pritchard, H. Robinson, M.K. Gorny, X. Yu, C. Bailey-Kellogg, M.E. Ackerman, C. Scanlan, and G. Alter, "Identification of antibody glycosylation structures that predict monoclonal antibody Fc-effector function", AIDS, 2014, 28:2523-2530.

OBJECTIVE: To determine monoclonal antibody (mAb) features that predict Fc-mediated effector functions against HIV.

DESIGN:: Monoclonal antibodies, derived from Chinese hamster ovary cells or EBV-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, antibody -dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and for the ability to bind to Fc?RIIa, Fc?RIIb and Fc?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?RIIIa binding strongly predicted ADCC and decreased galactose content inversely correlated with ADCP, whereas N-glycolylneuraminic acid-containing structures exhibited enhanced ADCP. Additionally, the bi-antenary glycan arm onto which galactose was added predicted enhanced binding to Fc?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.