Structure, function, and regulation of the interleukin-2 receptor and identification of a novel immune activation gene

Anti-CD25 (daclizumab) monoclonal antibody therapy in relapsing-remitting multiple sclerosis

Following the recent approval of the first oral therapy for multiple sclerosis (MS), fingolimod, multiple other oral compounds, and also a number of monoclonal antibodies (mab) are currently in phase III clinical testing. One of these is daclizumab, a humanized mab against the interleukin-2 receptor alpha chain (IL2RA or CD25). Efficacy to block clinical and inflammatory activity of relapsing-remitting MS (RR-MS) has been shown for daclizumab in several small phase IIa studies and one large phase IIb clinical trial, and phase III testing is ongoing. Different from prior expectations about its mechanism of action that anticipated that daclizumab would block the activation and expansion of autoreactive T cells, we and others have shown that the expansion of regulatory natural killer (NK) cells, which express high levels of the marker CD56, appears to be the most important biological effect of CD25 blockade. From these data CD25 inhibition is one of the most promising upcoming treatments of RR-MS and possibly also other autoimmune conditions. Clinical and mechanistic data will be summarized in this short review.

Intratumoral delivery of IL-18 naked DNA induces T-cell activation and Th1 response in a mouse hepatic cancer model

BACKGROUND

The novel cytokine, interleukin (IL)-18, is a strong interferon-gamma inducer and costimulatory factor in Th1 cell activation. IL-18 triggers IFN-gamma production and enhances cytolytic activity in both T and NK cells. However, the exact mechanism of antitumor action of IL-18 remains to be clarified. To determine the effects of IL-18 plasmid DNA on hepatic cancer in mice, CT26 murine colon adenocarcinoma cells were established in mouse liver.

METHODS

Plasmid vectors encoding IL-18 were transferred directly into the liver 7 days after tumor injection to restrict IL-18 expression within the tumor site. The IL-18 protein level was increased in the liver 4 days after plasmid injection, and a marked antitumoral effect was observed at day 7. Antitumor effects were evaluated by measuring tumor regression, immune cell population, and IFN-gamma production.

RESULTS

The IL-18 plasmid controlled the growth of hepatic tumors and proliferation of splenic immune cells. Moreover, treatment of CT26 tumors with the IL-18 plasmid significantly enhanced the population of the effector T and NK cells in the spleen and peripheral blood. In spleen, the population of CD4+CD62Low cells was augmented in response to IL-18 on day 7. These results are consistent with the increase in CD4+ T cells secreting IFN-gamma, but not CD8+ T cells. The marked reduction of tumor growth in tumor-bearing mice was associated with the maintenance of IFN-gamma production in spleen in response to IL-18. These antitumoral effects were maintained until 14 days after plasmid injection.

CONCLUSION

Our results suggest that direct plasmid DNA transfer of IL-18 with no accompanying reagents to augment transfection efficiency may be useful in tumor immunotherapy.

Differential transcription factor expression in human mononuclear cells in response to amphotericin B: identification with complementary DNA microarray technology

STUDY OBJECTIVE

To identify genes differentially expressed in human monocytic cells exposed to amphotericin B in vitro.

DESIGN

In vitro experiment.

SETTING

Hospital laboratory.

MATERIAL

Human mononuclear cell line, THP-1.

INTERVENTION

Human mononuclear cells were exposed to amphotericin B or media alone for 6 hours. After exposure, total RNA was isolated and reverse transcribed to complementary DNA. Differences in probe hybridization observed during blotting were measured, and genes with altered regulation were described by using human complementary DNA microarray technology.

MEASUREMENTS AND MAIN RESULTS

Of 588 genes represented on the array, 16 transcripts were found to be upregulated and 4 transcripts were downregulated in response to amphotericin B. These findings suggest that amphotericin B alters the expression of genes in human monocytic cells that play a role in many cellular functions, including immune response, signal transduction, and cell differentiation.

CONCLUSION

Amphotericin B induces alterations in human cell gene transcription. These changes could be used to evaluate differences in toxicity or efficacy observed in patients receiving this agent.

Increase in gamma interferon-secreting CD8(+), as well as CD4(+), T cells in lungs following aerosol infection with Mycobacterium tuberculosis

Although it is well established that CD4(+) T cells are required for the protective immune response against tuberculosis (TB), there is some evidence that CD8(+) T cells are also involved in the host response to Mycobacterium tuberculosis. There is, however, a paucity of information on the pulmonary CD8(+) T-cell response during infection. We therefore have compared the changes in both CD8(+) and CD4(+) T cells following aerosol infection with M. tuberculosis. There was an observed delay between the peak of infection and the activated T-cell response in the lung. The kinetics of CD8(+) and CD4(+) T-cell responses in the lung were identical, both peaking at week 8, 4 weeks later than the peak of cellular response in draining lymph nodes. Similar changes in activation/memory phenotypes occurred on the pulmonary CD8(+) and CD4(+) T cells. Following in vitro restimulation, both subsets synthesized gamma interferon, a cytokine essential for controlling M. tuberculosis infection. Since lung CD8(+) T cells are actively expanded during aerosol M. tuberculosis infection, it is important that both CD8(+) and CD4(+) T cells be targeted in the design of future TB vaccines.