Cytotoxic lymphocytes serve a key role in immune homeostasis by eliminating virus-infected and transformed target cells through the perforin-dependent delivery of proapoptotic granzymes. However, the mechanism of granzyme entry into cells remains unresolved. Using biochemical approaches combined with time-lapse microscopy of human primary cytotoxic lymphocytes engaging their respective targets,...

The lymphocyte pore-forming protein perforin is essential for maintaining immune homeostasis and for effective defense against intracellular pathogens. To date, there have been no reported structure-function studies to substantiate the function of any putative domains of perforin, which have been postulated totally on primary sequence similarities with domains in other proteins. In this report,...

CTLs and NK cells use the perforin/granzyme cytotoxic pathway to kill virally infected cells and tumors. Human regulatory T cells also express functional granzymes and perforin and can induce autologous target cell death in vitro. Perforin-deficient mice die of excessive immune responses after viral challenges, implicating a potential role for this pathway in immune regulation. To further inves...

Perforin-mediated cytotoxic T cell killing has been suggested to be of importance in the control of noncytopathic virus infections, based on studies with lymphocytic choriomeningitis virus (LCMV). We examined the role of perforin in a mouse model of gammaherpesvirus infection using transgenic perforin-deficient mice. Previous work from this laboratory has shown that CD8 T cells are essential fo...

We present methodologic details and operating characteristics of a procedure with whole blood for the quantitative assessment of intracellular perforin within distinct lymphocyte subsets. Using this method, we analyzed 20 healthy controls and 2 individuals with an inherited deficiency of perforin. The mean +/- standard deviation perforin contents of natural killer (NK) cells and cytotoxic T cel...

Because GALT is a major portal of entry for HIV-1 and reservoir for viral replication, we hypothesized that an ineffective cellular immune response in intestinal mucosa might partially explain the failure of immune control in AIDS. In this study, we demonstrate that the vast majority of CD8+ T cells in rectal tissue, including HIV-1-specific cells, fail to express the cytolytic protein, perfori...

Natural killer cells are important cytolytic cells in innate immunity. We have characterized human NK cells of spleen, lymph nodes, and tonsils. More than 95% of peripheral blood and 85% of spleen NK cells are CD56(dim)CD16(+) and express perforin, the natural cytotoxicity receptors (NCRs) NKp30 and NKp46, as well as in part killer cell Ig-like receptors (KIRs). In contrast, NK cells in lymph n...

The autosomal recessive immunodeficiencies Griscelli syndrome type 2 (GS2) and familial hemophagocytic lymphohistiocytosis type 3 (FHL3) are associated with loss-of-function mutations in RAB27A (encoding Rab27a) and UNC13D (encoding Munc13-4). Munc13-4 deficiency abrogates NK-cell release of perforin-containing lytic granules induced by signals for natural and antibody-dependent cellular cytoto...

Autoimmune diabetes in nonobese diabetic (NOD) mice results from destruction of pancreatic beta cells by T lymphocytes. It is believed that CD8(+) cytotoxic T lymphocytes (CTLs) effect the initial beta-cell insult in diabetes, but the mechanisms remain unclear. Studies of NOD.lpr mice have suggested that disease initiation is a Fas-dependent process, yet perforin-deficient NOD mice rarely devel...

In graft-versus-leukemia (GVL) responses, the cellular subsets and effector mechanisms responsible for cytotoxicity against leukemic cells in vivo remain poorly characterized. A murine model of syngeneic GVL that features CD4(+) and CD8(+) T-cell responses against the MMB3.19 myeloid leukemia cell line has been previously described. MMB3.19 expresses high levels of functional Fas and tumor necr...