Key molecules involved in receptor-mediated lymphocyte activation

Artificial antigen-presenting cells: the booster for the obtaining of functional adoptive cells

Adoptive cell therapy (ACT) achieves substantial efficacy in the treatment of hematological malignancies and solid tumours, while enormous endeavors have been made to reduce relapse and extend the remission duration after ACT. For the genetically engineered T cells, their functionality and long-term anti-tumour potential depend on the specificity of the T cell receptor (TCR) or chimeric antigen receptor (CAR). In addition, the therapeutic benefit is directly to sufficient activation and proliferation of engineered T cells. Artificial antigen-presenting cells (aAPCs), as powerful boosters for ACT, have been applied to provide sustained stimulation of the cognate antigen and facilitate the expansion of sufficient T cells for infusion. In this review, we summarize the aAPCs used to generate effector cells for ACT and underline the mechanism by which aAPCs enhance the functionality of the effector cells. The manuscript includes investigations ranging from basic research to clinical trials, which we hope will highlight the importance of aAPCs and provide guidance for novel strategies to improve the effectiveness of ACT.

Oligodeoxynucleotides expressing polyguanosine motifs promote antitumor activity through the upregulation of IL-2

The primary goal of cancer immunotherapy is to elicit an immune response capable of eliminating the tumor. One approach toward accomplishing that goal uses general (rather than tumor-specific) immunomodulatory agents to boost the number and activity of pre-existing CTLs. We find that the intratumoral injection of polyguanosine (poly-G) oligonucleotides (ODN) has such an effect, boosting antitumor immunity and promoting tumor regression. The antitumor activity of poly-G ODN was mediated through CD8 T cells in a TLR9-independent manner. Mechanistically, poly-G ODN directly induced the phosphorylation of Lck (an essential element of the T cell-signaling pathway), thereby enhancing the production of IL-2 and CD8 T cell proliferation. These findings establish poly-G ODN as a novel type of cancer immunotherapy.

Human immunodeficiency virus type 1 envelope gp120-induced partial T-cell receptor signaling creates an F-actin-depleted zone in the virological synapse

Cell-to-cell transmission of human immunodeficiency virus type 1 (HIV-1) occurs via a virological synapse (VS), a tight cell-cell junction formed between HIV-infected cells and target cells in which the HIV-1-infected cell polarizes and releases virions toward the noninfected target cell in a gp120- and intercellular adhesion molecule 1 (ICAM-1)-dependent process. The response of the target cell has been less studied. We utilized supported planar bilayers presenting gp120 and ICAM-1 as a reductionist model for the infected-cell membrane and investigated its effect on the target CD4 T cell. This study shows that HIV-1 gp120 interaction with its receptors is initially organized into microclusters that undergo F-actin-dependent consolidation into a central supramolecular activation complex (cSMAC). Src kinases are active in both gp120 microclusters and in the VS cSMAC. The early T-cell receptor (TCR) signaling machinery is partially activated at the VS, and signaling does not propagate to trigger Ca(2+) elevation or increase CD69 expression. However, these partial TCR signals act locally to create an F-actin-depleted zone. We propose a model in which the F-actin-depleted zone formed within the target CD4 T cell enhances the reception of virions by releasing the physical barrier for HIV-1 entry and facilitating postentry events.

A comprehensive review of immunosuppression used for liver transplantation

Since liver transplantation was approved for the treatment of end stage liver disease, calcineurin inhibitors (CNI's) have played a critical role in the preservation of allograft function. Unfortunately, these medications cause a variety of Side effects such as diabetes, hypertension and nephrotoxicity which in turn result in significant morbidity and reduced quality of life. A variety of newer immunosuppressants have been evaluated over the last decade in an attempt to either substitute for CNI's or use with reduced dose CNI's while still preserving allograft function However, current data does not recommend complete cessation of CNI's due to unacceptably high rates of allograft rejection. As these medications have their own unique adverse effects, a careful assessment on their risks and benefits is essential, particularly when additive or synergistic effects with CNI's may occur. Furthermore, the impact of these newer medications on the risk of hepatitis C recurrence and progression remains to be elucidated. Controlled trials are urgently required to assist transplant physicians with choosing the optimum immunosuppressive regimen for their patients. This review will discuss commonly used immunosuppressants prescribed in liver transplantation, emerging therapties and where appropriate, the impact of these medications on the recurrence of hepatitis C after liver transplantation.