Differential subcellular localization of CD86 in human PBMC-derived macrophages and DCs, and ultrastructural characterization by immuno-electron microscopy.

We have previously reported the presence of a discrete reservoir of the costimulatory molecule CD86 in the cytoplasm of human monocytes freshly isolated from peripheral blood mononuclear cells (PBMC). In the current study, we have extended analysis of the subcellular localization of this molecule to in vitro PBMC-derived dendritic cells (DCs) and macrophages. In a sub-population of DCs, we observed by confocal microscopy an intracellular focal concentration of CD86 that bore striking similarities to that previously reported in monocytes.

CD4 expression on EL4 cells as an epiphenomenon of retroviral transduction and selection.

The EL4 murine tumour cell line, isolated from a chemically induced lymphoma over 50 years ago, has been extensively exploited in immunological research. The conclusions drawn from many of these studies have been based on the presumption that EL4 cells maintain a stable phenotype during experimental manipulation. To the contrary, we have observed 100-fold greater expression of cell surface CD4 (CD4(high)) on a subpopulation of EL4 cells following retroviral transduction and G418 selection when compared with unmodified populations.

HeLa cells cocultured with peripheral blood lymphocytes acquire an immuno-inhibitory phenotype through up-regulation of indoleamine 2,3-dioxygenase activity.

The mechanisms by which tumour cells escape recognition by the immune system or subvert antitumour effector responses remain poorly understood. In the course of investigating the potential of costimulatory signals in anticancer immunotherapy strategies, we have observed that HeLa cells (a human cervical carcinoma cell line) cocultured with peripheral blood lymphocytes (PBL) acquire the capacity to inhibit PBL proliferation in response to interleukin-2 (IL-2). This immuno-inhibitory phenotype was further shown to result from induction of the tryptophan-catabolizing enzyme, indoleamine 2,3-dioxygenase (IDO), by interferon-gamma (IFN-gamma) secreted from cocultured allo-reactive PBL.

The adenovirus E4 ORF6 and E1b 55 kDa proteins cooperate in a p53-independent manner to enhance transduction by recombinant adeno-associated virus vectors.

The observation that exposure of target cells to genotoxic stress or adenovirus infection enhances recombinant adeno-associated virus (rAAV) transduction is an important lead towards defining the rAAV transduction mechanism, and has significant implications for the exploitation of rAAV in gene therapy applications. The adenovirus-mediated enhancement of rAAV transduction has been mapped to the E4 ORF6 gene, and expression of E4 ORF6 alone has been considered necessary and sufficient to mediate this effect. Since p53 subserves an important function in the cellular response to genotoxic stress, and interacts with the E4 ORF6 gene product during adenovirus infection, we hypothesized that p53 function might be essential to the rAAV enhancement resulting from these cellular insults.