To investigate the question of whether lytic granules share a common biogenesis with lysosomes, cloned cytolytic T cell lines were derived from a patient with I-cell disease. The targeting of two soluble lytic granule components, granzymes A and B, was studied in these cells which lack a functional mannose-6-phosphate (Man-6-P) receptor-mediated pathway to lysosomes. Using antibodies and enzyma...

Circulation Research is available at http://circres.ahajournals.org DOI: 10.1161/CIRCRESAHA.116.304734 Rationale: CD4+ natural killer T (NKT) cells augment atherosclerosis in apolipoprotein E–deficient (ApoE)−/− mice but their mechanisms of action are unknown. Objectives: We investigated the roles of bystander T, B, and NK cells; NKT cell–derived interferon-γ, interleukin (IL)-4, and IL-21 cyto...

In tumor cells, the serine protease granzyme B is the primary mediator of apoptosis induced by cytotoxic T lymphocytes (CTLs)/natural killer (NK) cells. The human intracellular serpin proteinase inhibitor 9 (PI9) is the only known human protein able to inhibit the proteolytic activity of granzyme B. When present in the cytoplasm of T lymphocytes, PI9 is thought to protect CTLs against apoptosis...

Granzyme B (GranB), a serine protease stored in the granules of cytotoxic T lymphocytes and natural killer cells, can initiate target cell apoptosis. To produce large amounts of purified active enzyme, recombinant murine granzyme B (rGranB) was expressed from baculovirus in insect cells. The expressed rGranB is secreted into the culture medium and can be readily purified to homogeneity by one-s...

Reactive oxygen species (ROS) are involved in cell signaling, aging, and death and play a role in carcinogenesis. However, whether ROS are bystanders or active effectors of apoptosis was unclear until recently. New evidence shows that the killer lymphocyte protease granzyme B activates a conserved biochemical pathway centered on respiratory chain disruption to trigger mitocentric ROS-dependent ...

Glioblastoma multiforme (GBM), is the most common adult brain tumor and despite many new therapies, remains largely incurable. Regulatory T cells (Treg) are highly immunosuppressive cells that accumulate within glioma microenvironment, and reduction of their function or trafficking has been previously shown to enhance survival in pre-clinical models of GBM. One of the principal mechanisms of Tr...

An interaction that gets things started he nuclear envelope clearly helps regulate eukaryotic DNA replication, but many of the molecular pieces of this process are still unknown. On page 177, Martins et al. describe a novel, direct interaction between the nuclear envelope and the genome, mediated by the inner nuclear membrane protein LAP2b and the nuclear matrix– associated protein HA95, that i...

Killer lymphocytes induce apoptosis by the release of cytotoxic mediators from specialized secretory lysosomes, called cytotoxic granules, into the immunological synapse formed with a cell targeted for elimination. Methods are presented here for isolating CTL and NK cell cytotoxic granules using cell disruption by nitrogen cavitation followed by continuous Percoll density gradient fractionation...