Effects ofFCGRIIIa-158V/F polymorphism on antibody-dependent cellular cytotoxicity activity of adalimumab

FcγRIIIa receptor polymorphism influences NK cell mediated ADCC activity against HIV

BACKGROUND

HIV-specific Antibody Dependent Cell Cytotoxicity (ADCC) has shown to be important in HIV control and resistance. The ADCC is mediated primarily by natural killer cell activated through the binding of FcγRIIIa receptor to the Fc portion of antibody bound to the antigen expressed on the infected cells. However, no data is available on the influence of the polymorphism in FcγRIIIa receptor on HIV-specific ADCC response.

METHODS

The Sanger's method of sequencing was used to sequence the exon of FcγRIIIa receptor while the ADCC activity was determined using NK cell activation assay. The polymorphism in FcγRIIIa receptor was assessed in HIV-infected Indian individuals with or without HIV-specific ADCC antibodies and its influence on the magnitude of HIV-specific ADCC responses was analyzed.

RESULTS

Two polymorphisms: V176F (rs396991) and Y158H (rs396716) were observed. The Y158H polymorphism is reported for the first time in Indian population. Both, V176F (V/V genotype) (p = 0.004) and Y158H (Y/H genotype) (p = 0.032) were found to be significantly associated with higher magnitude of HIV-specific ADCC response.

CONCLUSION

The study underscores the role of polymorphism in the FcγRIIIa receptor on HIV-specific ADCC response and suggests that the screening of the individuals for FcγRIIIa-V176F and Y158H polymorphisms could be useful for prediction of efficient treatment in monoclonal antibody-based therapies aimed at ADCC in HIV infection.

Effects of Soluble Tumor Necrosis Factor (TNF) on Antibody-Dependent Cellular Cytotoxicity of Therapeutic anti-TNF-α Antibody

Anti-TNF antibodies are major therapeutics for rheumatoid arthritis and have been approved for marketing in many countries. Antibody-dependent cellular cytotoxicity (ADCC) is considered to be a potential mechanism of action of anti-TNF antibodies, since some anti-TNF antibodies have been confirmed to induce cytotoxic effects on TNF-producing cells via ADCC and complement-dependent cytotoxicity (CDC) in in vitro experiments. In this study, we established a new stable effector cell line expressing human FcγRIIIa, CD16:KHYG-1, and compared the performance of this cell line with that of peripheral blood mononuclear cells (PBMCs) in ADCC assays against CHO-derived target cells expressing protease-sensitive pro-TNF. Although an inhibitory effect of soluble TNF released from pro-TNF expressing cells on ADCC activity was seen, clear dose-responsive ADCC activities were observed even in the presence or absence of TNF-α converting enzyme (TACE) inhibitor. However, significant differences in the ADCC activities in the presence or absence of TACE inhibitor were only noted when CD16:KHYG-1 cells were used as the effector cells. Our findings indicate that soluble TNF may influence ADCC activity of anti-TNF antibody. Moreover, the fact that the influence was able to be detected only in the case using stable effector cell also suggests that the stable effector cell established this time enable highly accurate ADCC measurement.