In vitro complex formation between granzyme A (GrA) and antithrombin III (ATIII), results in a decrease in GrA antigenic recovery.

Isolated GrA (18 ng) was incubated with a 200-fold excess of ATIII in the presence or absence of heparin (10 U) in phosphate-buffered saline/0.1% (w/v) Tween-20 for 30 minutes at 20°C. Various dilutions of the mixtures were then tested in the enzyme-linked immunosorbent assay (ELISA) for GrA-ATIII complexes (A) or in the ELISA for antigenic GrA (B) as described in “Materials and Methods.” The X-axis represents the final concentration of GrA in the wells, the Y-axis is the observed OD at 450 nm.