Characterization of interleukin 2-dependent cytotoxic T-cell clones. IV. Production of alpha, beta and gamma interferons and interleukin 2 by Lyt-2+ T cells

Th1: mediator lymphocytes in experimental autoimmune labyrinthitis

A previous study on experimental autoimmune labyrinthitis (EAL) consistently demonstrated transient infiltration of lymphocytes only into the inner ear of mice. To clarify the profile of lymphocytes in the initiation of EAL, the present study investigated cell surface antigens, as well as cytokines, from Day 4 to Day 35, using immunohistochemical techniques. Many CD4+ cells mainly infiltrated the endolymphatic sac as early as Day 4 and gradually spread to the rest of the inner ear. Infiltration peaked on Day 12 and persisted in most animals until Day 35, although the number of cells gradually decreased. In contrast, very few CD8+ cells were found to have appeared in the inner ear of all animals on Day 10, and the number of cells rapidly decreased. Many cells positive for IFN-gamma and IL-2 were identified in the endolymphatic sac on Day 4. These results suggest that helper T1 lymphocytes, rather than cytotoxic T lymphocytes, may play a central role in the initiation of EAL.

Target cell specificity of immunosuppression in murine lymphocytes exposed to 1,4-bis[(2-aminoethyl)amino]-5,8-dihydroxy-9,10-anthracenedione dihydrochloride (AEAD)

Exposure of murine lymphocytes to the highly-substituted anthraquinone 1,4-bis[(2-aminoethyl)amino]-5,8-dihydroxy-9,10-anthracenedione dihydrochloride (AEAD) results in a profound suppression of cytotoxic T-lymphocyte function. This immunosuppression is confined to CTL induction and cannot be restored by addition of exogenous interleukin-2 (IL-2), suggesting a defect at the level of the cytotoxic T-lymphocyte precursor (CTLp) cell. Production of both IL-1 and IL-2 were normal, and responsiveness to IL-1 was unaltered, although lymphocytes displayed a reduced responsiveness to IL-2. Cell surface marker analysis demonstrated no changes in relative numbers of lymphoid cell subsets, implying functional rather than population changes. The ability to activate CTLp with lectins was markedly reduced, as was CTL induction in thymocytes lacking functional T-helper cells. These data suggest that CTL suppression following in vivo or in vitro exposure to AEAD is due primarily to a direct effect on the CTLp cell.

Production of interferon-beta by murine T-cell lines induced by 10-carboxymethyl-9-acridanone

Besides the established T-cell property of producing gamma interferon (IFN-gamma), murine T cells additionally possess the ability to produce IFN-alpha and IFN-beta when appropriate inducers such as 10-carboxymethyl-9-acridanone (CMA) or Newcastle disease virus (NDV) are used. Interleukin 2 (IL-2)-dependent murine T-cell lines, but not purified resting splenic T cells, responded to CMA and NDV with production of IFN-alpha, beta. The IFN production by these T cells was not restricted to a special subset, since T cells expressing the Lyt 1+2- and the Lyt 1-2+ phenotype responded to these inducers with IFN production. After prolonged passaging of the T-cell lines in IL-2-containing medium, the ability to respond to CMA with production of antiviral activity was sustained longer than the ability for concanavalin A-induced IFN-gamma production. Whereas the NDV-induced T-cell supernates contained both IFN-alpha and IFN-beta, the induction with CMA resulted exclusively in the synthesis of IFN-beta by the T-cell lines.

Biology of cloned cytotoxic T lymphocytes specific for lymphocytic choriomeningitis virus: clearance of virus and in vitro properties

We have generated lymphocytic choriomeningitis virus-specific, H-2-restricted cytotoxic thymus-derived lymphocyte (CTL) clones. By using these reagents in several in vitro assays with infected target cells, we show that CTLs by themselves prevent the release of infectious virus into culture fluids and significantly lower the titers of infectious virus previously produced. This ability of cloned CTLs is not influenced by monensin. However, monensin does abrogate the ability of CTLs from spleens of mice primed 6 to 8 days previously with virus to kill virus-infected syngeneic targets. When tested for the participation of lymphokines in this system, the CTLs proliferate when reacted with syngeneic lymphocytic choriomeningitis virus-infected macrophages but fail to make interleukin-2. These CTLs make gamma interferon when reacted with syngeneic virus-infected targets. However, the production of interferon does not directly correlate with CTL-mediated killing. The number of H-2K and D molecules expressed on the target cell surface is not altered during the course of lymphocytic choriomeningitis virus infection. Electron microscopy shows finger-like projections of the CTL clone thrust into the infected cell and lesions bearing an internal diameter of approximately 15 nm in those membranes, illustrating the lytic process.

Characterization of interleukin 2 (IL-2)-dependent cytotoxic T-cell clones. V. Transfer of resistance to allografts and tumor grafts requires exogenous IL-2

The adoptive transfer of resistance to tumor grafts with cloned interleukin 2 (IL-2)-dependent cytotoxic T-cell lines was examined. Two clones were used: clone CTLL-A2 which recognizes H-2Dd determinants and clone CTLL-R5 which recognizes a unique cell surface antigen of BALB/c leukemia RL male 1. Systemic transfer of resistance with these clones was accomplished only when exogenous (rat or human) IL-2 was administered at the same time. Intraperitoneal injection of CTLL-A2 cells accelerated rejection of sarcoma Meth A (H-2Dd), but not ascites sarcoma BP8 (H-2k) or leukemia EL4 (H-2b) inoculated subcutaneously into C57BL/6 mice. CTLL-R5 cells were examined in local (Winn tests) as well as systemic transfer experiments. When mixed with leukemia cells before subcutaneous injection, they suppressed the growth of leukemia RL male 1 without exogenous IL-2. When injected intraperitoneally, CTLL-R5 cells inhibited the growth of subcutaneous grafts of leukemia RL male 1 only when exogenous IL-2 was administered at the same time. CTLL-R5 did not inhibit the growth of other radiation-induced BALB/c leukemias.

Biological and antigenic similarities of murine interferon-gamma and macrophage-activating factor

Murine peritoneal exudate cells (PEC) treated with murine recombinant interferon-gamma (IFN-gamma) (greater than 99% estimated purity), or concanavalin A-stimulated spleen cell supernatants developed tumoricidal properties (macrophage activation factor [MAF] activity). MAF activity was found to occur with treatments of 10 U/ml IFN-gamma, and at levels as low as 1 U/ml IFN-gamma if a second signal (5 ng/ml endotoxin) was present in the MAF assay. Endotoxin (lipopolysaccharide [LPS]) alone at these levels failed to induce MAF; induction of MAF was observed at 1,000-fold greater levels. The ability of IFN-gamma to stimulate murine PEC was species specific. Various sources of materials that displayed MAF activity, including supernatants from interleukin 2-dependent cloned cytotoxic murine T lymphocyte lines that did not display detectable antiviral activity, were neutralized by antibody raised and affinity purified against recombinant IFN-gamma. Thus, IFN-gamma, although never detectable by antiviral assays, appears to be present in many lymphokine preparations and has potent macrophage activation capability.