In vitro HIV-specific CTL activity from HIV-seropositive individuals is augmented by interleukin-12 (IL-12)

Activation of HIV type 1 specific cytotoxic T lymphocytes from semen by HIV type 1 antigen-presenting dendritic cells and IL-12

Seminal HIV-1-specific cytotoxic T lymphocytes (CTLs) could provide an important immune defense against local HIV-1 infection, and be important in impeding the spread of HIV-1 infection. In this study, we demonstrate that autologous blood-derived dendritic cells (DCs) loaded in vitro with synthetic HIV-1 peptides representing known CTL epitopes activated HLA class I restricted, anti-HIV-1 CTLs and interferon gamma responses in seminal CD8+ T cells from subjects with chronic HIV-1 infection on antiretroviral therapy. CTLs specific for the same HLA-restricted epitopes were detected in semen and blood of the same individuals by stimulation with peptide-loaded DCs. Anti-HIV-1 CTL responses from semen were enhanced by stimulation with DCs loaded with HIV-1 peptides and interleukin 12. Our results suggest that blood-derived DCs have HIV-1 antigen-presenting capacity for seminal CTL in HIV-1-infected subjects. The DC-T cell system can serve as a model for immunotherapy of HIV-1 infection in the local genital tract as well as systemic blood circulation.

CD8+ T cells specific for EBV, cytomegalovirus, and influenza virus are activated during primary HIV infection

Primary viral infections, including primary HIV infection, trigger intense activation of the immune system, with marked expansion of CD38(+)CD8(+) T cells. Whether this expansion involves only viral-specific cells or includes a degree of bystander activation remains a matter of debate. We therefore examined the activation status of EBV-, CMV-, and influenza virus (FLU)-specific CD8(+) T cells during primary HIV infection, in comparison to HIV-specific CD8(+) T cells. The activation markers CD38 and HLA-DR were strongly expressed on HIV-specific CD8(+) T cells. Surprisingly, CD38 expression was also up-regulated on CD8(+) T cells specific for other viruses, albeit to a lesser extent. Activation marker expression returned to normal or near-normal values after 1 year of highly active antiretroviral therapy. HIV viral load correlated with CD38 expression on HIV-specific CD8(+) T cells but also on EBV-, CMV-, and FLU-specific CD8(+) T cells. In primary HIV infection, EBV-specific CD8(+) T cells also showed increased Ki67 expression and decreased Bcl-2 expression, compared with values observed in HIV-seronegative control subjects. These results show that bystander activation occurs during primary HIV infection, even though HIV-specific CD8(+) T cells express the highest level of activation. The role of this bystander activation in lymphocyte homeostasis and HIV pathogenesis remains to be determined.

Expansion of EBV latent membrane protein 2a specific cytotoxic T cells for the adoptive immunotherapy of EBV latency type 2 malignancies: influence of recombinant IL12 and IL15

BACKGROUND

EBV-associated malignancies with a Type II latency gene expression pattern, such as EBV-positive HD, or nasopharyngeal carcinoma, frequently express the EBV latency Ag LMP2a. Hence, they provide a potential target for adoptive immunotherapy using in vitro-generated LMP2a-specific cytotoxic T lymphocytes (CTL). In this study, LMP2a-specific CTL were specifically amplified and the influence of rIL12 and rIL15 on the culture outcome was tested.

METHODS

PBMC from donors were stimulated twice with autologous DC transduced with an adenovirus vector expressing LMP2a. This led to a significant expansion of LMP2a-tetramer-specific CTL, which were subsequently further expanded with autologous EBV-transformed B-lymphoblastoid cells (LCL). The addition of rIL12 and rIL15 to the standard IL2-containing culture medium enhanced the proliferation of LMP2a-specific CTL.

RESULTS

While rIL15 did not change the pattern of cytokines secreted by LMP2a-CTL, rIL12 enhanced the production of Th1/Tc1 cytokines, such as IFN-n, while suppressing the production of the Th2/Tc2 cytokine IL5.

DISCUSSION

Stimulation of CTL cultures with rIL12 or rIL15 will generate CTL more rapidly, facilitating the application of this approach for patients with these EBV-associated disorders.

Interleukin 12-augmented T cell proliferation of peripheral blood mononuclear cells from HIV-seropositive individuals is associated with interleukin 12 receptor beta 2 upregulation

Interleukin 12 (IL-12) production is believed to be impaired in individuals with HIV infection and this impairment manifests early in disease, when the CD4(+) cell counts are within normal values. The reduced antigen-specific and mitogen-stimulated T cell-proliferative responses that occur in HIV infection can be corrected by the addition of recombinant human interleukin 12 (rhIL-12). As the IL-12 receptor (IL-12R) is central to the IL-12 signaling pathway, we examined whether the augmentation of antigen-specific proliferation of HIV(+) peripheral blood mononuclear cells (PBMCs) related to altered IL-12R expression. rhIL-12 augmented antigen-specific proliferation of HIV(+) PBMCs but not of HIV(-) PBMCs. Examination of resting PBMCs from HIV(+) and HIV(-) donors showed that neither of these populations expressed IL-12R beta 1 or IL-12R beta 2 chains on their cell surface as detected by flow cytometry. However, examination of mRNA showed that both IL-12R beta 1 and IL-12R beta 2 mRNAs were markedly reduced in HIV(+) PBMCs when compared with HIV(-) PBMCs. After mitogen activation there was an increase in IL-12R beta 1 expression on the cell surface of HIV(+) and HIV(-) PBMCs and this level was not altered by coculture with rhIL-12 or interferon gamma (IFN-gamma). However, coculture of phytohemagglutinin (PHA)-activated HIV(+) or HIV(-) PBMCs with rhIL-12 (but not IFN-gamma) increased IL-12R beta 2 expression on the cell surface of both populations. Examination at the message level showed a correction of IL-12R beta 1 to normal levels with activation that was further enhanced by rhIL-12 coculture for both the HIV(+) and HIV(-) PBMCs. However, although the level of IL-12R beta 2 for the HIV(+) PBMCs was normalized by PHA, rhIL-12 caused a further augmentation. This information provides a strong link between IL-12R upregulation, and the significant improvement in antigen-specific HIV-proliferative responses seen with the addition of rhIL-12. It also reveals that the dysfunction in IL-12R expression seen in cells from HIV(+) patients occurs at the transcriptional level. In addition, we provide further evidence that IL-12R beta 1 and IL-12R beta 2 regulation in human PBMCs is independent of IFN-gamma.

Active cellular infection of myeloid cells is required for HIV-1-mediated suppression of interleukin-12 p40 expression

Immunodeficiency during HIV infection is associated with impaired production of interleukin-12 (IL-12). Here we examine the requirement for active cellular infection, the role of other cytokines, and the molecular target of HIV-mediated suppression of IL-12. The reduction in LPS-induced IL-12 p40 protein and mRNA following acute in vitro HIV infection of THP-1 cells and monocytes was not attributed to IL-10 or TGF-beta activity and was not restored by priming with IL-4, IL-13, or IFN-gamma. Suppression of IL-12 was dependent upon active cellular infection and replication and not due to any soluble host or viral factors in HIV-infected cultures. Significant reduction in transcription of IL-12 p40 was observed following acute HIV infection. These results suggest that impaired IL-12 production in HIV-infected myeloid cells occurs, in part, via disruption of IL-12 p40 gene expression in a manner that requires cellular infection, highlighting the need to study myeloid cells in isolation during acute HIV-1 infection.

Administration of recombinant rhesus interleukin-12 during acute simian immunodeficiency virus (SIV) infection leads to decreased viral loads associated with prolonged survival in SIVmac251-infected rhesus macaques

The ability of recombinant rhesus interleukin-12 (rMamu-IL-12) administration during acute simian immunodeficiency virus SIVmac251 infection to influence the quality of the antiviral immune responses was assessed in rhesus macaques. Group I (n = 4) was the virus-only control group. Group II and III received a conditioning regimen of rMamu-IL-12 (10 and 20 microg/kg, respectively, subcutaneously [s.c.]) on days -2 and 0. Thereafter, group II received 2 microg of IL-12 per kg and group III received 10 microg/kg s.c. twice a week for 8 weeks. On day 0 all animals were infected with SIVmac251 intravenously. While all four group I animals and three of four group II animals died by 8 and 10 months post infection (p.i.), all four group III animals remained alive for >20 months p.i. The higher IL-12 dose led to lower plasma viral loads and markedly lower peripheral blood mononuclear cell and lymph node proviral DNA loads. During the acute viremia phase, the high-IL-12-dose monkeys showed an increase in CD3(-) CD8 alpha/alpha(+) and CD3(+) CD8 alpha/alpha(+) cells and, unlike the control and low-IL-12-dose animals, did not demonstrate an increase in CD4(+) CD45RA(+) CD62L(+) naive cells. The high-IL-12-dose animals also demonstrated that both CD8 alpha/alpha(+) and CD8 alpha/beta(+) cells produced antiviral factors early p.i., whereas only CD8 alpha/beta(+) cells retained this function late p.i. Long-term survival correlated with sustained high levels of SIV gag/pol and SIV env cytotoxic T lymphocytes and retention of high memory responses against nominal antigens. This is the first study to demonstrate the capacity of IL-12 to significantly protect macaques from SIV-induced disease, and it provides a useful model to more precisely identify correlates of virus-specific disease-protective responses.