The fate of adoptively transferred quiescent encephalitogenic T cells in normal and antigen-tolerized mice

Glioma stem cells and immunotherapy for the treatment of malignant gliomas

Stem cell research has led to the discovery of glioma stem cells (GSCs), and because these cells are resistant to chemotherapy and radiotherapy, analysis of their properties has been rapidly pursued for targeted treatment of malignant glioma. Recent studies have also revealed complex crosstalk between GSCs and their specialized environment (niche). Therefore, targeting not only GSCs but also their niche may be a principle for novel therapies of malignant glioma. One possible novel strategy for targeting GSCs and their niches is immunotherapy with different antitumor mechanism(s) from those of conventional therapy. Recent clinical studies of immunotherapy using peptide vaccines and antibodies have shown promising results. This review describes the recent findings related to GSCs and their niches, as well as immunotherapies for glioma, followed by discussion of immunotherapies that target GSCs for the treatment of malignant glioma.

Cross-priming of T cells to intracranial tumor antigens elicits an immune response that fails in the effector phase but can be augmented with local immunotherapy

Central nervous system (CNS) tumors are thought to be poorly immunogenic. However, whether defective anti-tumor immunity is a consequence of a relative failure of T cell priming versus a deficient effector phase of the anti-tumor immune response is not clear. We utilized a well-defined model system of B16 melanoma expressing the model antigen SIY-GFP to evaluate tumor antigen cross-priming and tumor rejection from the CNS versus subcutaneous compartments. We observed that B16-SIY cells implanted in the CNS were capable of inducing T cell priming as measured by IFN-gamma ELISPOT in the spleen. Cross-priming occurred in the absence of detectable systemic dissemination of the tumor. Despite the induction of a T cell response, CNS tumors grew progressively and were fatal, whereas the same tumor implanted in the flank was rejected. To study the effector phase of the immune response in more detail, in vitro primed 2C/RAG2-/- TCR transgenic CD8+ cells, which recognize the SIY peptide, were adoptively transferred. In addition, the CNS microenvironment was modulated by intracranial delivery of IL-2. While mice that received primed 2C cells alone showed an increase in survival, co-administration of intracranial IL-2 led to a marked prolongation of survival, with 20% of mice surviving at least 120 days. Our results demonstrate that CD8+ T cell cross-priming does indeed occur in response to a CNS tumor, but that manipulation of the brain tumor microenvironment may be necessary to support the effector phase of the anti-tumor immune response.

Comparison of ventricular and lumbar cerebrospinal fluid T cells in non-inflammatory neurological disorder (NIND) patients

The aim of the present study was to define the cellular composition of ventricular, as compared with lumbar, cerebrospinal fluid (CSF) in patients with non-inflammatory neurological disorders (NIND). We addressed this issue by determining the cellular composition of lumbar CSF from patients with normal pressure hydrocephalus (NPH) who were undergoing lumbar CSF drainage during evaluation for shunting procedures, and evaluating ventricular CSF from a subset of these who underwent subsequent placement of ventriculoperitoneal shunts. We determined the cellular composition of lumbar CSF from 18 patients with NPH, and found that the leukocyte differentials, and relative proportions of CD4+ and CD8+ central memory (TCM), effector memory (TEM) and naive cell (TNaive) populations, were equivalent to those found previously in studies of CSF from patients with NIND. We further evaluated cells in the ventricular CSF of five patients who had previously undergone lumbar drainage. Leukocyte differential counts, as well as CD4+ and CD8+ TCM, TEM, and TNaive proportions, were equivalent in matched ventricular and lumbar CSF samples. These observations support the hypothesis that leukocytes enter the CSF in a selective fashion, at its site of formation in the choroid plexus. The results implicate CSF T cells in the immune surveillance of the central nervous system.

Immunoregulation of CNS autoimmunity by helminth and mycobacterial infections

The 'hygiene hypothesis' has been proposed to explain apparent increases in autoimmune disease and allergy in areas of the world with improved health care and sanitation. This hypothesis proposes that the lack of serious childhood infections impairs development of an appropriately educated immune response. Imbalance of Th1 and Th2 responses and lack of regulatory T-cell populations are two of many proposed potential mechanisms for immune failures such as autoimmunity and allergy. We summarize the literature evidence for the influence of infectious organisms on autoimmunity with focus on helminth and mycobacterial infections. We also demonstrate that Schistosoma mansoni ova pretreatment, Mycobacterium bovis (BCG) infection, and lyophilized Mycobacterium tuberculosis all modify the course of clinical disease in mice induced for experimental autoimmune encephalomyelitis (a mouse model for human multiple sclerosis (MS)). Our data supports the applicability of the hygiene hypothesis to CNS autoimmune disease.

Basic principles of immunological surveillance of the normal central nervous system

Unlike most bodily organs, the central nervous system (CNS) exists behind a blood-tissue barrier designed to minimize the passage of cells and macromolecules into the neural parenchyma. Yet, the CNS is routinely and effectively surveyed by the immune system. This review examines the mechanisms and participants in this immunological surveillance mechanism. The nature of the healthy blood-brain barrier, factors modifying it, and its central position in determining the number and nature of leukocytes permitted to enter, are considered. In addition the role in surveillance played by lymphatic drainage, migrating T and B lymphocytes, and elements of the monocyte/macrophage/microglia family are considered. While all these participants are known to be important in responding to a CNS antigen and/or establishing a site of inflammation in the nervous system, they also are major elements in maintaining the homeostasis of the CNS and permitting the necessary immunological surveillance of that organ.

Regulation of experimental autoimmune encephalomyelitis in the C57BL/6J mouse by NK1.1+, DX5+, alpha beta+ T cells

C57BL/6 (B6) mice with targeted mutations of immune function genes were used to investigate the mechanism of recovery from experimental autoimmune encephalomyelitis (EAE). The acute phase of passive EAE in the B6 mouse is normally resolved by partial recovery followed by mild sporadic relapses. B6 TCR beta-chain knockout (KO) recipients of a myelin oligodendrocyte glycoprotein p35-55 encephalitogenic T cell line failed to recover from the acute phase of passive EAE. In comparison with wild-type mice, active disease was more severe in beta(2)-microglobulin KO mice. Reconstitution of TCR beta-chain KO mice with wild-type spleen cells halted progression of disease and favored recovery. Spleen cells from T cell-deficient mice, IL-7R KO mice, or IFN-gamma KO mice were ineffective in this regard. Irradiation or treatment of wild-type spleen cell population with anti-NK1.1 mAb before transfer abrogated the protective effect. Removal of DX5(+) cells from wild-type spleen cells by anti-DX5 Ab-coated magnetic beads before reconstitution abrogated the suppressive properties of the spleen cells. TCR-deficient recipients of the enriched DX5(+) cell population recovered normally from passively induced acute disease. DX5(+) cells were sorted by FACS into DX5(+) alpha beta TCR(+) and DX5(+) alpha beta TCR(-) populations. Only recipients of the former recovered normally from clinical disease. These results indicate that recovery from acute EAE is an active process that requires NK1.1(+), DX5(+) alpha beta(+) TCR spleen cells and IFN-gamma.