TARGETED T-CELL THERAPY FOR HUMAN LEUKEMIA - CYTOTOXIC T-LYMPHOCYTES SPECIFIC FOR A PEPTIDE DERIVED FROM PROTEINASE-3 PREFERENTIALLY LYSE HUMAN MYELOID-LEUKEMIA CELLS

Proteinase 3 is present in high concentration in the primary granules of acute and chronic myeloid leukemia blasts, and may represent a pote ntial T-cell target antigen. We screened proteinase 3 against the bind ing motif of HLA-A2.1. Based on its high predicted binding, a 9-mer pe ptide, ''PR-1,'' was synthesized and tested for binding to HLA-A2.1 us ing the T2 cell line. PR-1 at 100 mu g/mL significantly increased expr ession of HLA-A2.1, with median channel of fluorescence increasing fro m 22 to 294. Binding half-life was determined to be 1,460 minutes by I -125-labeled beta(2) . microglobulin incorporation. HLA-A2.1(+) periph eral blood mononuclear cells from a normal donor were used to generate a T-cell line specific for PR-1. The line demonstrated 85% PR-1-speci fic lysis at an E:T ratio of 50:1, compared with 20% lysis without PR- 1, using T2 cells as targets. It also showed 79% specific lysis to fre sh chronic myelogenous leukemia blasts, 54% to fresh acute myelogenous leukemia blasts, and only background lysis (<20%) to HLA-A2.1(+) norm al allogeneic marrow cells. The amount of lysis of HLA-A2.1(+) myeloid cells was proportional to cytoplasmic proteinase 3 expression. Thus, HLA-A2.1-restricted cytotoxic T cells, raised against a peptide contai ned in proteinase 3, preferentially lysed fresh human leukemic cells. This is a US government work, There are no restrictions on its use.