Targeted T-cell therapy for human leukemia: Cytotoxic T lymphocytes specific for a peptide derived from proteinase 3 preferentially lyse human myeloid leukemia cells

Abstract

Proteinase 3 is present in high concentration in the primary granules of acute and chronic myeloid leukemia blasts, and may represent a potential T- cell target antigen. We screened proteinase 3 against the binding motif of HLA-A2.1. Based on its high predicted binding, a 9-mer peptide, 'PR-1,' was synthesized and tested for binding to HLA-A2.1 using the T2 cell line. PR-1 at 100 μg/mL significantly increased expression of HLA-A2.1, with median channel of fluorescence increasing from 22 to 294. Binding half-life was determined to be 1,460 minutes by I125-labeled β2-microglobulin incorporation. HLA-A2.1+ peripheral blood mononuclear cells from a normal donor were used to generate a T-cell line specific for PR-1. The line demonstrated 85% PR-l-specific lysis at an E:T ratio of 50:1, compared with 20% lysis without PB-1, using T2 cells as targets. It also showed 79% specific lysis to fresh chronic myelogenous leukemia blasts, 54% to fresh acute myelogenous leukemia blasts, and only background lysis (