Interleukin-2-dependent augmentation of the anti-TNP antibody production by sodium butyrate in cultured murine splenic B cells.

Previously we found that sodium butyrate (NaBu) markedly enhanced production of the antibody specific for a T-cell-dependent antigen, sheep red blood cells (SRBC) in murine splenocytes (Kishiro, Y., Ueda, K., Fujiwara, M. and Yamamoto, I., Jpn J. Phamacol., 1994 66, 369-376. To gain a better understanding of the target cells for NaBu's action on antibody responses, we have utilized the T-cell-independent antigen, trinitrophenyl-lypopolysaccharide (TNP-LPS) as a stimulant and have examined an effect of NaBu on the anti-TNP antibody production in vitro. NaBu markedly increased the anti-TNP plaque-forming cell (PFC) responses in murine whole splenocytes, but not in murine splenic B cells. Addition of T-cells or the concanavalin A supernatant (CAS) from murine splenocytes to the B cell cultures completely restored the enhancing effect of NaBu. This effect of CAS was totally blocked by an anti-interleukin (IL)-2 antibody and partially by an anti-IL-1 beta or anti-IL-4 antibody. The full enhancing effect of NaBu was also detected when IL-2 was added to the B cell cultures, while IL-2 alone had no stimulatory effect on the control PFC response. IL-1 beta alone significantly stimulated the antibody production and adding NaBu to this IL-1 beta-supplemented culture caused a further increase. Neither IL-4 alone nor NaBu plus IL-4 had any effect on the PFC response. NaBu did not affect the expression of the IL-2 receptor alpha- and beta-chains in B cells stimulated with TNP-LPS. These results suggest that NaBu is an agent that promotes B cell differentiation in vitro in an IL-2-dependent manner.

Induction of hepatocyte growth factor in human skin fibroblasts by epidermal growth factor, platelet-derived growth factor and fibroblast growth factor.

Hepatocyte growth factor (HGF) is a potent mitogen for rat and human hepatocytes in primary culture and appears to be the physiological hepatotrophic factor that triggers or modulates liver regeneration. Regulation of HGF gene expression and the protein production in human skin fibroblasts was examined. Addition of epidermal growth factor (EGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), acidic fibroblast growth factor (aFGF) and transforming growth factor-alpha (TGF-alpha) to confluent cultures of the cells markedly stimulated HGF secretion from the cells. The stimulating effect of EGF, PDGF and bFGF was further investigated. The effect of all three growth factors was maximal at 3-30 ng/ml and was accompanied by an increase in HGF mRNA levels. The mRNA levels were not elevated at 5 h but were at 10 h or more after addition of EGF. The levels of HGF mRNA in fibroblasts treated with the optimal doses of EGF, PDGF, bFGF, aFGF and TGF-alpha for 24 h were 6, 4, 5, 4 and 5 times that of control cultures incubated in medium only, respectively. The growth factor-induced HGF mRNA expression and HGF secretion was inhibited by addition of TGF-beta 1 or dexamethasone. Pretreatment with a high dose of phorbol 12-myristate 13-acetate (PMA), which causes down-regulation in protein kinase C (PKC) activity and PMA-induced HGF secretion, did not reduce the effects of the growth factors on HGF mRNA expression and HGF secretion, but rather enhanced them.(ABSTRACT TRUNCATED AT 250 WORDS)