Hemopoietic cell kinase (Hck) and p21-activated kinase 2 (PAK2) are involved in the down-regulation of CD1a lipid antigen presentation by HIV-1 Nef in dendritic cells.

Dendritic cells (DCs) play a major role in in vivo pathogenesis of HIV-1 infection. Therefore, DCs may provide a promising strategy to control and eventually overcome the fatal infection. Especially, immature DCs express all CD1s, the non-MHC lipid antigen -presenting molecules, and HIV-1 Nef down-regulates CD1 expression besides MHC.

Induction of apoptosis-resistant and TGF-β-insensitive murine CD8(+) cytotoxic T lymphocytes specific for HIV-1 gp160.

Although TGF-β and IL-6 would turn CD8(+) T cells to differentiate into non-cytotoxic state, these treated cells were converted to cytolytic phenotypes after re-exposure to their antigenic epitope in vitro. Here, using spleen cells from TCR transgenic mice expressing TCRαβ genes of clone RT1 recognizing an epitope peptide (P18-I10: RGPGRAFVTI) of HIV-1 gp160, we generated CD8(+) cytotoxic T lymphocytes (CTLs) activated by re-exposure to P18-I10 after primarily cultured with TGF-β and IL-6 in vitro to examine their effector function. The CTLs, having strong cytotoxic activity in vitro, were not only resistant to Fas-FasL mediated apoptosis, but also insensitive to the suppression of their cytotoxicity by re-exposure to TGF-β in vitro.

Quick method of multimeric protein production for biologically active substances such as human GM-CSF (hGM-CSF).

The C-terminal fragment of C4b-binding protein (C4BP)-based multimerizing system was applied to hGM-CSF to induce dendritic cells (DCs) from peripheral blood monocytes (PBMCs), to see whether the C4BP could stimulate immature DCs, since DCs, equipped with pattern recognition receptors such as toll-like receptors (TLRs), are hypersensitive to various immunologically active molecules like LPS. hGM-CSF gene was merged to the 3'-terminal region of the C4BPalpha-chain gene, and the transfected human 293FT cells produced sufficient amount of octameric hGM-CSF, which resulted in iDCs with the same phenotype and the same response to a TRL4 ligand, LPS and a TLR3 ligand, poly I:C, as those induced with authentic monomeric hGM-CSF. These results suggest that the C4BP-based multimerizing system could facilitate the design of self-associating multimeric recombinant proteins without stimulating iDCs, which might be seen with the other multimerizing systems such as that using Fc fragment of IgM.

A possible mechanism of intravesical BCG therapy for human bladder carcinoma: involvement of innate effector cells for the inhibition of tumor growth.

Intravesical bacillus Calmette-Guerin (BCG) therapy is considered the most successful immunotherapy against solid tumors of human bladder carcinoma. To determine the actual effector cells activated by intravesical BCG therapy to inhibit the growth of bladder carcinoma, T24 human bladder tumor cells, expressing very low levels of class I MHC, were co-cultured with allogeneic peripheral blood mononuclear cells (PBMCs) with live BCG. The proliferation of T24 cells was markedly inhibited when BCG-infected dendritic cells (DCs) were added to the culture although the addition of either BCG or uninfected DCs alone did not result in any inhibition.

Transmission of macrophage-tropic HIV-1 by breast-milk macrophages via DC-SIGN.

Recent findings suggest that macrophage-tropic human immunodeficiency virus type 1 (HIV-1) produced in colostrum/early breast milk may hold a clue to determine the mechanisms of transmission of HIV-1 via breast-feeding. Here, we show that the majority of CD4(+) cells in the colostrum are CD14(+) macrophages expressing both chemokine receptors and DC-SIGN, a dendritic cell-specific receptor for HIV-1. The R5-type macrophage-tropic HIV-1 isolate NL(AD8) infected such breast-milk macrophages and caused them to secrete virus particles efficiently; however, the secreted virions showed only a weak transmissibility to their susceptible target, MAGIC-5 cells.

Endogenously expressed HIV-1 nef down-regulates antigen-presenting molecules, not only class I MHC but also CD1a, in immature dendritic cells.

The effects of Nef molecules on immature dendritic cells (iDCs) were analyzed using recombinant human immunodeficiency virus type 1 (HIV-1) with intact nef gene, pseudotyped with vesicular stomatitis virus glycoprotein, HIV/VSV-G/+Nef. When iDCs were infected with HIV/VSV-G/+Nef, the surface expression of CD1a, a molecule for presenting glycolipid/lipid antigens, was selectively down-regulated among CD1 molecules (CD1a, -b, -c, and -d) as well as class I MHC. Moreover, the CD1a molecules were also down-modulated and co-localized with DsRed2-tagged-Nef in CD1a-transfected cells.

Perforin-dependent killing of tumor cells by Vgamma1Vdelta1-bearing T-cells.

The T-cell subset expressing Vdelta2 paired primarily with Vgamma2 comprises a majority of gammadelta T-cells in human adult peripheral blood and expands significantly during a variety of infectious diseases. In contrast, the other subset of gammadelta T-cells that express Vdelta1 is rare among circulating T-cells and its function is poorly understood. Here, we show that a Vgamma1Vdelta1(+) T-cell line, 3-D, established from human peripheral blood by immortalization with Herpesvirus saimiri was able to specifically recognize tumor cells, such as K562 cells, and release cytotoxic granules containing perforin for target cell killing.