Background: DSA+ CABMR constitutes the major cause for renal allograft loss in the U.S. Currently there are no approved therapies. We have reported TCZ use for pre-Tx desensitization (DES) and CABMR Rx. Complement- (CDC) and Ab-dependent cellular cytotoxicity (ADCC) are mechanisms for ABMR mediated primarily by IgG1&3 subclasses. We previously showed that TCZ-Rx reduced all 4 IgG subclasses, but reduction of IgG3 elevated pre-TCZ was most significant. Here we determined if TCZ-Rx reduced IgG1-4 subclasses and anti-HLA IgG subclasses. Methods: Archived plasma obtained pre- & post-TCZ-Rx (8mg/kg, 6x, monthly) from 15 Pts were tested for total IgG & IgG1-4 by ELISA, and anti-HLA total IgG, IgG3&4 by luminex. Anti-HLA total IgG (class I & II) levels were expressed as score (score 10, 5, 2 & 0 for SFI>200K, 100K-200K, <100K & 0, respectively, are given to each detected Ab), and IgG3&4 as MFI. The sum of the scores and MFIs were the final levels for serum w/ multiple Abs. Pre-TCZ IL-6 levels were also measured by luminex. Results: Total IgG, IgG1-4, and anti-HLA total IgG, DSA & IgG3 were significantly decreased post-TCZ (Table 1). No DSA was IgG3 subclass. Anti-HLA IgG4 also decreased, but not significantly. There was no correlation between pre-TCZ IL-6 and all types of IgGs tested. Conclusions: TCZ-Rx reduces total IgG, all 4 IgG subclass, anti-HLA total IgG, DSA, IgG3&4 subclass levels, indicating that IgG reduction by TCZ is non-specific via its anti-B cell property. This suggests that TCZ could reduce both CDC and ADCC-mediated ABMR.

*p<0.0.5 & 0.05<#P<0.1 vs. pre-TCZ.

CITATION INFORMATION: Shin B.-H, Everly M, Choi J, Ge S, Petrosyan A, Vo A, Jordan S, Toyoda M. Tocilizmab (Anti-IL-6R) Treatment (TCZ-Rx) Reduced Total IgG Levels Including Anti-HLA IgG: Analysis of IgG Subclasses (IgG1-IgG4) and Anti-HLA IgG Subclasses Show Similar Reductions in All Subclasses from Patients with DSA+ Chronic Antibody-Mediated Rejection (CABMR). Am J Transplant. 2017;17 (suppl 3).

« Back to 2017 American Transplant Congress