Expression of HECA-452 epitopes and PSGL-1 after bromelain treatment.

To remove HECA-452 epitopes displayed by PSGL-1 and disrupt the selectin-binding function of CLA, human CLA⁺ and CLA^low T cells were treated with 0.1% bromelain and then examined for HECA-452 and PSGL-1 polypeptide expression. In panels A and B, membrane proteins were prepared from human CLA⁺T-cell cultures treated with bromelain in parallel with flow cytometry experiments. Membrane proteins (10 μg per lane) were resolved on 6% reducing SDS-PAGE gels and blotted onto PVDF membrane. Western blotting with anti–PSGL-1 moAbs PL-1, 2G3, 4F9, and 4D8 (2 μg/mL each) or moAb HECA-452 (1.0 μg/mL) revealed that HECA-452 epitopes (panel A, lane 2) and PSGL-1 polypeptide (panel B, lane 2) were absent after bromelain treatment.