Effect of trastuzumab interchain disulfide bond cleavage on Fcγ receptor binding and antibody-dependent tumour cell phagocytosis.

The Fc domain of human IgG1 binds to Fcγ receptors (FcγRs) to induce effector functions such as phagocytosis. There are four interchain disulfide bonds between the H and L chains. In this study, the disulfide bonds within the IgG1 trastuzumab (TRA), which is specific for HER2, were cleaved by mild S-sulfonation or by mild reduction followed by S-alkylation with three different reagents.

Antibody-dependent cellular cytotoxicity and cytokine/chemokine secretion by KHYG-1 cells stably expressing FcγRIIIA.

Antibody-dependent cellular cytotoxicity (ADCC) mediated by natural killer (NK) cells is a major mechanism of tumor therapy with antibodies. NK cells not only manifest cytotoxicity but also secrete a variety of cytokines/chemokines that regulate immune responses. Using a retroviral vector, in this study we established a KHYG-1 cell line that stably expresses FcγRIIIA (CD16A).

Cleavage of the interchain disulfide bonds in rituximab increases its affinity for FcγRIIIA.

The Fc region of human IgG1 mediates effector function via binding to Fcγ receptors and complement activation. The H and L chains of IgG1 antibodies are joined by four interchain disulfide bonds. In this study, these bonds within the therapeutic IgG1 rituximab (RTX) were cleaved either by mild reduction followed by alkylation or by mild S-sulfonation; consequently, two modified RTXs - A-RTX (alkylated) and S-RTX (S-sulfonated) - were formed, and both were almost as potent as unmodified RTX when binding CD20 antigen.

A neuronal transmembrane protein LRFN4 complexes with 14-3-3s and NCK1 to induce morphological change in monocytic cells via Rac1-mediated actin cytoskeleton reorganization.

We previously reported that leucine-rich repeat and fibronectin type III domain-containing 4 (LRFN4) functioned in migration and morphological change (i.e. cell elongation) of monocytic cells.

The ASB2β Ubiquitin-interacting motif is involved in its monoubiquitination.

ASB2 proteins are E3 ubiquitin (Ub) ligases that ubiquitinate filamins. There are two ASB2 splice variants, ASB2α and ASB2β. ASB2β has a ubiquitin-binding motif (UIM) at the N-terminal region but ASB2α does not.