#55-OR
SUCCESSFUL FLOW CROSSMATCHING IN RENAL TRANSPLANT PATIENTS WITH THYMOGLOBULIN USING A NEW ABSORBED REAGENT.
Isabelle G. Wood, BS , Edgar L. Milford, MD and Fang Ji MA . Boston MA, Brigham and Women
s Hospital, 02115, Tissue Typing Lab and New England Organ Bank .
Flow cytometric crossmatching (FXM) can be used to detect antidonor antibody after Rabbit anti-thymocyte globulin (ATG) therapy. ATG can cause false positive cytotoxic and flow crossmatches. We obtained a newly developed FITC conjugated F(ab')2 fragment Goat anti-Human IgG (Fc Gamma specific) absorbed for minimal crossreactivity to Rabbit, Mouse and Bovine (Jackson Immuno-Research Lab #109096170) (ABS Anti-Hu) and tested it for crossreactivity to ATG and for sensitivity in detecting anti-HLA antibodies. ABS Anti-Hu had low non-specific binding in T and B cell FXMs yet equal sensitivity in detecting anti-HLA antibodies. Patients were tested from day 0 to 81 post ATG treatment. One 0% PRA patient had high levels of ATG, using with FITC anti-Rabbit (left figure), which caused strong false positives with the standard Anti-Hu reagent (Std) not seen with the ABS Anti-Hu (right figure).
Three unsensitized (including patient in figs. above) and 2 sensitized patients were followed post ATG. In 32/34 post Tx FXMs using ABS Anti-Hu, crossmatches remained unaffected by ATG. Overall the ABS product has had a 10 fold reduction in non-specific binding to ATG. The sensitivity and specificity of the absorbed anti-Human make this an excellent reagent for monitoring ATG patients.