Selective regulation of CD8 effector T cell migration by the p110 gamma isoform of phosphatidylinositol 3-kinase.

Chemokine-mediated T cell migration is essential to an optimal immune response. The p110gamma isoform of PI3K is activated by G protein-coupled receptors and regulates neutrophil and macrophage chemotaxis. We used p110gamma-deficient mice to examine the role of p110gamma in CD8 T cell migration and activation in response to viral challenge.

Protection from lethal infection by adoptive transfer of CD8 T cells genetically engineered to express virus-specific innate immune receptor.

CMV infection is one of the most common complications in immunocompromised individuals, such as organ and bone marrow transplant patients. Both innate and adaptive immune responses are required for defense against CMV infection. In murine CMV (MCMV) infection, strains harboring the MCMV-specific NK cell activation receptor, Ly49H (Klra8), are resistant.

Multiepitope Trojan antigen peptide vaccines for the induction of antitumor CTL and Th immune responses.

We describe in this study a strategy to produce synthetic vaccines based on a single polypeptide capable of eliciting strong immune responses to a combination CTL and Th epitopes with the purpose of treating malignancies or preventing infectious diseases. This strategy is based on the capacity of Trojan Ags to deliver exogenous Ags into the intracellular compartments, where processing into MHC-binding peptides takes place. Our previous work demonstrated that Trojan Ags containing a CTL epitope localized to intracellular compartments, where MHC class I-binding peptides were generated in a TAP-independent fashion by the action of various exopeptidases and the endopeptidase furin.

Chemokines promote quiescence and survival of human neural progenitor cells.

Many cell types in the brain express chemokines and chemokine receptors under homeostatic conditions, arguing for a role of these proteins in normal brain processes. Because chemokines have been shown to regulate hematopoietic progenitor cell proliferation, we hypothesized that chemokines would regulate neural progenitor cell (NPC) proliferation as well. Here we show that chemokines activating CXCR4 or CCR3 reversibly inhibit NPC proliferation in isolated cells, neurospheres, and in hippocampal slice cultures.

Specific ubiquitin-conjugating enzymes promote degradation of specific nuclear receptor coactivators.

Nuclear receptor coactivators (NRCoAs) are nuclear hormone receptor-associated regulatory proteins that interact with members of the nuclear receptor superfamily in the presence of their cognate ligand, enhancing their transcriptional activity. The identification of ubiquitin-proteasome pathway proteins as coactivators provides evidence that ubiquitin-proteasome-mediated protein degradation plays an integral role in eukaryotic gene transcription. It has also been observed that nuclear receptors themselves are ubiquitinated and degraded in a hormone-dependent manner and that ubiquitin-proteasome function is essential for most nuclear receptors to function as transactivators.

Identification of helper T-cell epitopes that encompass or lie proximal to cytotoxic T-cell epitopes in the gp100 melanoma tumor antigen.

The melanocyte-associated antigen gp100 constitutes one of the most attractive targets for T-cell-based immunotherapy against malignant melanoma. Although several MHC class I-restricted epitopes have been identified for CTLs, thus far, only one MHC class II T helper epitope (restricted by HLA-DR4) has been described in the literature. Using an algorithm to identify promiscuous helper T-cell epitopes, here we describe three additional MHC class II-restricted epitopes from gp100.

TAP-independent presentation of CTL epitopes by Trojan antigens.

The majority of CTL epitopes are derived from intracellular proteins that are degraded in the cytoplasm by proteasomes into peptides that are transported into the endoplasmic reticulum by the TAP complex. These peptides can be further processed into the optimal size (8-10 residues) for binding with nascent MHC class I molecules, generating complexes that are exported to the cell surface. Proteins or peptides containing CTL epitopes can be introduced into the cytoplasm of APCs by linking them to membrane-translocating Trojan carriers allowing their incorporation into the MHC class I Ag-processing pathway.

Defining promiscuous MHC class II helper T-cell epitopes for the HER2/neu tumor antigen.

It is accepted that both helper and CTLs play a critical role in immune antitumor responses. Thus, the design of effective immune-based therapies for cancer relies in the identification of relevant tumor-associated antigens (TAAs) capable of eliciting strong helper and cytotoxic T-cell responses against tumor cells. The product of the HER2/neu oncogene is considered as a prototype TAA, because it is found overexpressed in a large variety of malignancies, whereas normal cells only produce low levels of this product.

Use of two predictive algorithms of the world wide web for the identification of tumor-reactive T-cell epitopes.

Tumor cells can be effectively recognized and eliminated by CTLs. One approach for the development of CTL-based cancer immunotherapy for solid tumors requires the use of the appropriate immunogenic peptide epitopes that are derived from defined tumor-associated antigens. Because CTL peptide epitopes are restricted to specific MHC alleles, to design immune therapies for the general population it is necessary to identify epitopes for the most commonly found human MHC alleles.

Interleukin-3 and granulocyte-macrophage colony-stimulating factor enhance the generation and function of dendritic cells.

Dendritic cells, well-known for their potent antigen-presenting activity, are generally present at very low frequency in the spleens of naive mice. We examined the ability of mice to generate functional dendritic cells (DC) following exposure to the cytokines interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Tumours secreting these cytokines provided a continuous stimulus resulting in a greatly increased number and frequency of DC in the spleen.

Use of a beta1 integrin-deficient human T cell to identify beta1 integrin cytoplasmic domain sequences critical for integrin function.

T cell activation rapidly and transiently regulates the functional activity of integrin receptors. Stimulation of CD3/T cell receptor, CD2 or CD28, as well as activation with phorbol esters, can induce within minutes an increase in beta1 integrin-mediated adhesion of T cells to fibronectin. In this study, we have produced and utilized a mutant of the Jurkat T cell line, designated A1, that lacks protein and mRNA expression of the beta1 integrin subunit but retains normal levels of CD2, CD3, and CD28 on the cell surface.

IL-3 enhances both presentation of exogenous particulate antigen in association with class I major histocompatibility antigen and generation of primary tumor-specific cytolytic T lymphocytes.

Recent studies have reported that APC can present particulate exogenous Ag in the context of class I MHC to CD8+ CTL, and our laboratory demonstrated that IL-3 could enhance CTL generation to exogenous Ag. In this paper, we wished to determine whether presentation of particulate Ag could be enhanced by IL-3. A T cell hybridoma, B3Z86/90.

Differential selection of cells with proviral c-myc and c-erbB integrations after avian leukosis virus infection.

Avian leukosis virus (ALV) infection induces bursal lymphomas in chickens after proviral integration within the c-myc proto-oncogene and induces erythroblastosis after integration within the c-erbB proto-oncogene. A nested PCR assay was used to analyze the appearance of these integrations at an early stage of tumor induction after infection of embryos. Five to eight distinct proviral c-myc integration events were amplified from bursas of infected 35-day-old birds, in good agreement with the number of transformed bursal follicles arising with these integrations.

IL-3-mediated enhancement of particulate antigen presentation by macrophages.

Mice were exposed to interleukin- (IL-) 3 in vivo by injection of tumor cells transfected with the IL-3 gene. At 10 days post tumor injection, bone marrow cells were recovered, pulsed with particulate antigen in the form of ovalbumin (Ova)-coated magnetic beads, and tested for their ability to present antigen via class I to an Ova/class I-restricted T cell hybridoma. Cells from IL-3-stimulated mice exhibited a marked increase in antigen presentation compared with cells from mice injected with control non-cytokine-secreting tumor cells.

VBP and RelA regulate avian leukosis virus long terminal repeat-enhanced transcription in B cells.

The avian leukosis virus (ALV) long terminal repeat (LTR) contains a compact transcription enhancer that is active in many cell types. A major feature of the enhancer is multiple CCAAT/enhancer element motifs that could be important for the strong transcriptional activity of this unit. The contributions of the three CCAAT/enhancer elements to LTR function were examined in B cells, as this cell type is targeted for ALV tumor induction following integration of LTR sequences next to the c-myc proto-oncogene.

The avian C/EBPgamma gene encodes a highly conserved leucine zipper transcription factor.

The C/EBP family of transcription factors regulates viral and cellular CCAAT/enhancer element-mediated transcription. We report the isolation and characterization of genomic and cDNA clones encoding avian CCAAT/enhancer-binding protein-gamma (C/EBP gamma). A partial cDNA clone for a C/EBP-related gene was previously identified by expression library screening for proteins binding the A1 CCAAT/enhancer motif from the avian leukosis virus long terminal repeat [W.

Regulation of the activity of a new inhibitor of angiogenesis by a cancer suppressor gene.

An inhibitor has been identified in the conditioned medium of hamster cells and hamster-human hybrids that suppresses neovascularization in vivo in the rat cornea. Inhibitory activity was tightly linked to the presence of an active cancer suppressor gene in transformants and revertants, in segregating hybrids, and in temperature-limited transformants. It copurified with a approximately 140 kd glycoprotein.

Receptors for the Fc portion of immunoglobulin G (Fc gamma R) on human monocytes and macrophages.

Human mononuclear phagocytes bear a group of cell surface receptors that bind the Fc domain of IgG. These Fc gamma receptors are utilized in the phagocytosis of opsonized cells and immune complexes and are involved in the pathogenesis of several hematologic and immunologic disorders. However, the relative contributions of the different Fc gamma receptors to these processes is uncertain.