Levamisole regulates the proliferation of murine liver T cells through Kupffer-cell-derived cytokines.

We have previously shown that levamisole increases the cytotoxic, cytostatic, and proliferative activity of murine nonparenchymal liver cells (NPC) in vitro. We have also shown that the nonadherent subpopulation of NPC, which are composed predominantly of T lymphocytes, is very responsive to this agent when administered to mice. Kupffer cells or immigrant macrophages are also responsive to levamisole but to a lesser extent. These findings prompted us to investigate changes in cytokine production by NPC following-treatment of mice with levamisole (25 mg/kg, i.p.), which may help explain the observed alterations in the immune functions of these cells. We found that levamisole treatment of mice causes a threefold increase in production of interferon (IFN) alpha/beta by adherent NPC (more than 80%-90% Kupffer cells) in vitro. When IFN alpha/beta was added to cultured cells, it decreased the proliferative capacity of liver T cells in a dose-dependent manner. In contrast, the addition of anti-IFN alpha/beta was shown to augment levamisole-induced proliferation of unfractionated NPC and Kupffer cells. NPC production of interleukin 1 (IL-1) and interleukin-6 (IL-6) in vitro was also increased threefold following treatment of mice with levamisole. IL-6 added in vitro to cells significantly augmented levamisole-induced proliferation of liver T cells while anti-IL-6 reduced proliferative activity to control levels. These findings suggested that IFN alpha/beta, IL-6, and IL-1 play important regulatory roles in controlling the proliferative response of murine liver-associated T lymphocytes to levamisole. Finally, the proliferation of bone marrow cells was increased in mice given 5-fluorouracil (5FU). On the other hand, the proliferation of NPC was dramatically suppressed when 5FU was administered. However, the proliferation of these cells was restored when levamisole was given after 5FU.

Combination of cyclosporine and splenectomy suppresses interleukin-6 production and major histocompatibility complex class II expression and prolongs cardiac xenograft survival.

Although untreated Lewis rat recipients will reject a transplanted hamster heart in 3 days, accommodation of heart xenografts can be induced by treatment with cyclosporine and splenectomy, improving graft survival to greater than 50 days. Both humoral and cellular arms of the immune system may be involved in the mechanisms responsible for the prolongation of graft survival. Our objective was to study the impact of cyclosporine and splenectomy on the deposition of antibodies, complement, or both within the graft. We also compared the cellular component of inflammation in treated recipients with that in untreated controls. Inbred male Lewis rats given cyclosporine 15 mg/kg per day were splenectomized 2 days after they had received heterotopic heart transplants from Golden Syrian hamsters. Recipients of syngeneic grafts or untreated xenografts served as controls. Plasma interleukin-6 activity was measured in a standard proliferation assay with 7TD1 hybridoma cells. Deposition of immunoglobulin M, immunoglobulin G, and complement in heart tissue was evaluated by immunofluorescence. Cells infiltrating the graft that expressed major histocompatibility complex class II antigens were identified by immunohistochemical staining with OX6 antibodies. In xenograft recipients receiving immunosuppression, interleukin-6 activity, immunoglobulin M and complement deposition were significantly reduced, graft infiltration was mild, and cardiac function was good compared with the results in those without treatment 3 and 10 days after implantation. Inflammatory cells expressing major histocompatibility complex class II antigens were significantly reduced in immunosuppressed xenograft recipients (2.8 +/- 0.4 cells/high power field) compared with those in xenogeneic controls (9.5 +/- 0.6 cells/high power field; p < 0.0005). The significant decrease in deposition of humoral components (immunoglobulin M and complement), interleukin-6 plasma levels, and expression of major histocompatibility complex class II antigens by inflammatory cells within the nonrejecting grafts suggests that the synergistic benefit of cyclosporine and splenectomy depends on the attenuation of both cellular and humoral mechanisms of xenograft rejection.

Hepatic metastasis alters the immune function of murine liver nonparenchymal cells.

To examine the effect of a single hepatic focus of metastatic colon tumor on the immune function of liver non-parenchymal cells (NPCs) from C57Bl/6 mice, we injected 2.5 x 10(5) liver-derived murine colon adenocarcinoma (LD-MCA-38) cells beneath the liver capsule. Three weeks following injection of the tumor cells, the immune function of the NPCs was studied. The NPCs from tumor-bearing mice exhibited increased cytotoxic and proliferative activity. The NPCs from tumor-bearing mice also contained a greater percentage of CD8+ and T-cell receptor gamma/delta+ liver-associated T lymphocytes. Levels of interleukin 6 and tumor necrosis factor were increased in the NPC supernatant, and interleukin 6 levels were increased in serum from tumor-bearing mice. We conclude that the presence of a single hepatic focus of metastatic tumor results in augmented immune function of murine liver NPCs.

Augmentation of the immune response of the murine liver by levamisole.

Murine hepatic nonparenchymal cells (NPC) were studied following in vivo treatment with levamisole. This agent was found to increase the cytolytic action of these cells against YAC-1 and P815 target cells. An increase in the cytostatic activity against liver-derived murine colon adenocarcinoma 38 tumor cells was also observed. Treatment with levamisole also augmented the proliferation of the hepatic NPC. Supernatants generated by these cells contained an agent capable of stimulating the proliferation of bone marrow cells from the same mice. The effect of levamisole on different subsets of NPC derived from the liver in this model is discussed.