Abdul Tawab

Ex vivo characterization of polyclonal memory CD8 + T-cell responses to PRAME-specific peptides in patients with acute lymphoblastic leukemia and acute and chronic myeloid leukemia

Preferentially expressed antigen of melanoma (PRAME) is aberrantly expressed in hematologic malignancies and may be a useful target for immunotherapy in leukemia. To determine whether PRAME is naturally immunogenic, we studied CD8(+) T-cell responses to 4 HLA-A*0201-restricted PRAME-derived epitopes (PRA100, PRA142, PRA300, PRA425) in HLA-A*0201-positive patients with acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and healthy donors. CD8(+) T cells recognizing PRAME peptides could be detected ex vivo in 4 of 10 ALL, 6 of 10 AML, 3 of 10 CML patients, and 3 of 10 donors by HLA-A2 tetramer analysis and flow cytometry for intracellular interferon-gamma. The frequency of PRAME-specific CD8(+) T cells was greater in patients with AML, CML, and ALL than healthy controls. All peptides were immunogenic in patients, while responses were only detected to PRA300 in donors. High PRAME expression in patient peripheral blood mononuclear cells was associated with responses to greater than or equal to 2 PRAME epitopes compared with low PRAME expression levels (4/7 vs 0/23, P = .001), suggesting a PRAME-driven T-cell response. PRAME-specific T cells were readily expanded in short-term cultures in donors and patients. These results provide evidence for spontaneous T cell reactivity against multiple epitopes of PRAME in ALL, AML, and CML. The potential for developing PRAME as a target for immunotherapy in leukemia deserves further exploration.

A functional comparison of mature human dendritic cells prepared in fluorinated ethylene-propylene bags or polystyrene flasks

BACKGROUND: Fluorinated ethylene‐propylene (FEP) bags have been used instead of polystyrene (PS) flasks for ex vivo clinical‐scale production of human dendritic cells (DCs) to facilitate closed‐system recovery of these highly adherent cells. To assess the impact of DC culture on this nonadherent surface, the function of DCs generated in FEP and PS was compared.

Effect of ex vivo culture duration on phenotype and cytokine production by mature dendritic cells derived from peripheral blood monocytes

BACKGROUND: To generate clinical‐grade dendritic cells (DCs) ex vivo for immunotherapy trials, peripheral blood monocytes are typically cultured in granulocyte‐macrophage–colony‐stimulating factor (GM‐CSF) and interleukin (IL)‐4 and then matured using one or more agents. Duration of the initial DC culture is one important variable that has not been systematically evaluated for its effect on the characteristics of the final mature DC product.