IMMUNOBIOLOGY CD8 T-cell responses to Wilms tumor gene product WT1 and proteinase 3 in patients with acute myeloid leukemia

Wilms tumor gene product WT1 and proteinase 3 are overexpressed antigens in acute myeloid leukemia (AML), against which cytotoxic T lymphocytes can be elicited in vitro and in murine models. We performed this study to investigate whether WT1and proteinase 3-specific CD8 T cells spontaneously occur in AML patients. T cells recognizing HLA-A2.1binding epitopes from WT1 or proteinase 3 could be detected ex vivo in 5 of 15 HLA-A2–positive AML patients by interferon(IFN) ELISPOT assay and flow cytometry for intracellular IFNand in 3 additional patients by flow cytometry only. T cells producing IFNin response to proteinase 3 were further characterized in one patient by 4-color flow cytometry, identifying them as CD3 CD8 CD45RA CCR7 T cells, resembling cytotoxic effector T cells. In line with this phenotype, most of the WT1and proteinase-reactive T cells were granzyme B . These results provide for the first time evidence for spontaneous T-cell reactivity against defined antigens in AML patients. These data therefore support the immunogenicity of WT1 and proteinase 3 in acute leukemia patients and the potential usefulness of these antigens for leukemia vaccines. (Blood. 2002;100:2132-2137)