The immunomodulatory effects of 3-monochloro-1,2-propanediol on murine splenocyte and peritoneal macrophage function in vitro.

3-Monochloro-1,2-propanediol (MCPD) is a well-known by-product of acid-hydrolyzed soy sauce during its manufacturing process. MCPD has been reported genotoxic in vitro, and reproductive toxicity and carcinogenicity in rats. To evaluate the immunomodulatory effect of MCPD on murine splenocyte and macrophage in vitro, we investigated splenocyte blastogenesis by concanavalin A (Con A), anti-CD3, and lipopolyssacharide (LPS), the production of cytokines from splenocyte, and the activity of mouse peritoneal macrophages. There was a significant decrease in lymphocyte blastogenesis to Con A or anti-CD3 at subtoxic dose of MCPD. A significant decrease in splenocyte blastogenesis to LPS was also observed. The production level of interferon (IFN)-gamma on splenocyte culture with Con A was significantly reduced at the higher concentration than 1.0mM of MCPD. The levels of interleukin (IL)-4 and IL-10 were also decreased at high concentrations of MCPD. There was a significant decrease in production of nitric oxide (NO) by peritoneal macrophages treated with MCPD. MCPD also inhibits tumor necrosis factor (TNF)-alpha production of stimulated macrophages. These results indicate that MCPD might be able to reduce the functionality of lymphocytes and peritoneal macrophages in vitro.     

Beziehung zwischen dem UV-Absorptionsmuster einiger Flavone und ihrer gegen L1210-Zellen cytotoxischen Aktivität

The UV-pattern of several flavones, their cytotoxicities against L1210 cell and their Inhibiting effects on ATPase from the cell seem to be correlated. 5,2′-Dihydroxy-6,7,8,6′-tetramethoxyflavone (ED₅₀=2.3 ug/ml) and 5,2′,6′-trihydroxy-6,7,8-trimethoxyflavone (ED₅₀=4.5 ug/ml), the most active flavones studied, have shown a narrow range of the absorbance ratio, Log εII/Log εI=1.073～1.109. They have inhibited the ATPase-activity to the greatest extent. These findings suggest that a certain angle between the flavone rings B and C plays an important role for the inhibition of the enzyme activity and thus the cytotoxicity.     

Hydrogen peroxide-induced phospholipase D2 activation in lymphocytic leukemic L1210 cells

Extracellular hydrogen peroxide (H2O2) has been implicated in the activation of phospholipase D (PLD). However, it was still unclear how this activation occurs and what the molecular identity of the H2O2-stimulated PLD isozyme is. This study shows that H2O2 potently increases the PLD activity in mouse lymphocytic leukemic L1210 cells, which contain exclusively PLD2. In addition, H2O2 increased PLD activity only in PLD2-transfected COS-7 cells and not in PLD1-transfected cells. This suggests that PLD2 is selectively activated by H2O2. Depletion of extracellular Ca2+ with EGTA completely blocked the H2O2-induced PLD activation, indicating that Ca2+ influx is required. Moreover, pretreatment of the cells with the protein kinase C (PKC) inhibitors GF-109203X and RO-31-8220 and down-regulation of PKCalpha by prolonged treatment with 4beta-phorbol 12-myristate 13-acetate inhibited the H2O2-stimulated PLD2 activity, which points to the involvement of PKCalpha. Based on these new findings we suggest that PLD2 activity is specifically up-regulated by H2O2 and that the H2O2-induced PLD2 activation is mediated by Ca2+ influx and PKCalpha activation.