T-cell responses to peptide fragments of the BK virus T antigen: implications for cross-reactivity of immune response to JC virus.

Infection with BK virus (BKV) induces both humoral and cellular immunity, but the viral antigens of T-antigen (T-ag) stimulating T-cell responses are largely unknown. To identify BKV-specific T cells in healthy individuals, peripheral blood lymphocytes were cultured with autologous dendritic cells (DCs) loaded with BKV lysate and T cells were screened for intracellular gamma interferon production after stimulation with an overlapping 15mer peptide library of the BKV T-ag. Among many immunogenic peptides identified, four T-ag peptides were identified as candidate major histocompatibility complex class I and II T-cell epitopes, restricted to human leukocyte antigen (HLA)-B*0702, -B*08, -DRB1*0301 and -DRB1*0901.

High donor FOXP3-positive regulatory T-cell (Treg) content is associated with a low risk of GVHD following HLA-matched allogeneic SCT.

Regulatory T cells (T(reg)s) that constitutively express FOXP3 are instrumental to the maintenance of tolerance and may suppress graft-versus-host disease (GVHD) in humans. To determine whether regulatory T cells in allogeneic stem cell transplants (SCTs) ameliorate GVHD after transplantation, we quantitated the coexpression of FOXP3 on CD4(+) T cells in 32 donor SCTs infused into HLA-matched siblings and examined GVHD incidence in respective recipients. High CD4(+)FOXP3(+) T-cell count in the donor was associated with a reduced risk of GVHD.

T-cell responses directed against multiple HLA-A*0201-restricted epitopes derived from Wilms' tumor 1 protein in patients with leukemia and healthy donors: identification, quantification, and characterization.

Purpose: Antigens derived from the Wilms' tumor (WT1) protein, which is overexpressed in leukemias, are attractive targets for immunotherapy. Four HLA-A*0201-restricted WT1-derived epitopes have been identified: WT37, WT126, WT187, and WT235. We determined the natural immunogenecity of these antigens in patients with hematologic malignancies and healthy donor.