The interaction of recombinant IL-2 with human resting lymphocytes: blocking effects of monoclonal antibodies to IL-2 receptors

Effect of FK506 on the activation state of hepatic macrophages in Propionibacterium acnes-treated rats

Activated hepatic macrophages can provoke massive liver necrosis following endotoxin stimulation through microcirculatory disturbances due to sinusoidal fibrin deposition in rats pretreated with heat-killed Propionibacterium acnes. In these rats, FK506 (tachlorinus) administered 24 h before and at the time of endotoxin injection, significantly attenuated liver injury compared with the rats given no FK506. The effect of FK506 on hepatic macrophage activation and its action sites were studied in Propionibacterium acnes-treated rats. When rats received Propionibacterium acnes intravenously, hepatic-mRNA expression of interferon-γ-inducing factor and interleukin-2 and splenic-mRNA expression of interferon-γ were significantly increased compared with normal rats. Hepatic-mRNA expression of CD14, a receptor for lipopolysaccharide and its binding protein complex, was also increased preceding the expressions of the three cytokines in the liver and spleen. FK506 administration attenuated hepatic-mRNA expression of interleukin-2 and both superoxide anions as well as tumour necrosis factor-α production by hepatic macrophages, but did not change CD14-mRNA expression in Propionibacterium acnes-treated rats. It is suggested that a cytokine network through interferon-γ-inducing factor, interferon-γ and interleukin-2 may operate during activation of hepatic macrophages in rats treated with heat-killed Propionibacterium acnes, while CD14 expression on the cells may increase independently of this network. FK506 seems to attenuate such activation by suppressing hepatic interleukin-2 expression, without affecting CD14 expression on the cells.

Contribution of CD14 to endotoxin-induced liver injury may depend on types of macrophage activation in rats

Activated Kupffer cells and hepatic macrophages can produce massive liver necrosis through microcirculatory disturbance due to sinusoidal fibrin deposition. This mechanism is involved in the development of liver injury after endotoxin administration in rats pretreated with heat-killed Propionibacterium acnes (P.acnes) or undergoing 70% liver resection. The significance of CD14, a receptor for lipopolysaccharide and its binding protein, was evaluated in both models in relation to the activation mechanisms of Kupffer cells and hepatic macrophages. Northern blot analysis revealed that CD14 mRNA expression was increased in the liver of rats following P.acnes administration. In these rats, hepatic macrophages immediately after isolation showed marked increased of CD14 mRNA expression compared to Kupffer cells from normal rats. In contrast, CD14 mRNA expression was minimal in partially resected liver. Interleukin (IL)-18 and IL-2 mRNA expression in the liver and interferon (IFN)-gamma mRNA expression in the spleen were significantly increased in P.acnes-treated rats compared to normal rats, while these increases were absent in partially hepatectomized rats. Thus, CD14 expressed on hepatic macrophages after activation through a cytokine network of IL-18, IFN-gamma, and IL-2 may contribute to endotoxin-induced liver injury in P.acnes-treated rats. In contrast, in partially hepatectomized rats, this network may not operate during Kupffer cell activation, and the liver injury might develop through endotoxin receptors other than CD14 on the cells.

Cytotoxic effectors in human peripheral blood mononuclear cells induced by a mannoprotein complex of Candida albicans: a comparison with interleukin 2-activated killer cells

In this study, the major histocompatibility complex-unrestricted cytotoxic effectors elicited in human peripheral blood mononuclear cells (PBMC) by a mannoprotein (MP) component from the cell wall of the human indigenous microorganism Candida albicans have been compared with those obtained by stimulation with interleukin 2. (Interleukin 2-activated killer cells: LAK). It has been found that MP-induced lytic effectors were substantially similar to LAK in potency, target specificity, and type of precursor/effector cells. In both cases, natural killer (NK)-susceptible and NK-resistant targets as well as fresh tumor (glioma) cells were efficiently killed by a population of effectors showing a predominant CD3-, CD16+ phenotype. However, the precursors of MP-induced killers were highly sensitive to the lysosomotropic toxic drug L-leucine methyl ester (Leu-OME) whereas the generation of LAK cells was unaffected by this drug. The Leu-OME sensitivity of MP-induced cytotoxicity generation was not due to a nonspecific effect on antigen-presenting cells or inhibition of cell proliferation. In addition, the generation of MP-induced killer cells was totally abrogated by treatment with CD16 antibodies and complement, whereas a minor but significant fraction of LAK precursors was not susceptible to the above treatment. These results indicate that a defined component(s) of the cell wall of C. albicans has some properties of biological response modifiers in cultures of human PBMC in vitro.

Lymphokine-activated killer (LAK) activity against autologous malignant tumors of the skin

When peripheral blood mononuclear cells (PBMC) cultured with interleukin 2 (IL-2) develop the ability to lyse fresh tumor cells, such activity is referred to as lymphokine-activated killer (LAK) activity. In this paper, we examined LAK activity against the autologous skin tumors, malignant melanoma (MM), squamous cell carcinoma (SCC), and basal cell epithelioma (BCE), which have distinct clinical characteristics. Similar levels of LAK activity against Daudi 1A4, an NK resistant cell line were significantly obtained from all cancer patients. However, different levels of LAK activity against autologous tumor cells were found from three kinds of cancer patients using mixtures of autologous tumors and LAK. The levels of cytotoxicity were 29.8 +/- 7.0% in five MM, 15.9 +/- 4.9% in seven SCC, and 4.0 +/- 2.3% in five BCE patients at an effector/target ratio of 50/1. Allogeneic MM targets were lysed by LAK from all three types of cancer patients at similar levels, implying that LAK is not restricted to major histocompatibility complex (MHC) antigens. These results indicate that the levels of autologous LAK activity were significantly associated with the magnitude of clinical malignancy of the tumor targets, and suggested the selective lysis of tumor targets by LAK. NK activity of cancer patients bearing tumors was also examined prior to therapy. The levels of NK activity observed in MM patients were considerably lower than those in two other cancer patients.