Search

Boric acid was not mitogenic for human fibroblasts and it did not change cell viability until 0.5% (w/v). Boric acid treatment affected the metabolism of human dermal fibroblasts in culture, decreasing the synthesis of extracellular matrix macromolecules such as proteoglycans, collagen, and total proteins. It also increased the release of these molecules into the culture medium. The principal proteins secreted into the medium after boric acid treatment had molecular masses of 90, 70, 58, 49, and 43 kDa and faint bands were detected by electrophoresis between 14 and 30 kDa. hsp 70 and TNF alpha were detected among the secreted proteins by immunoblotting, and the amount of TNF alpha released was quantified by radioimmunoassay. Total mRNA levels were higher after boric acid treatment and peaked after 6 h of treatment. TNF alpha mRNA was undetectable in unstimulated fibroblasts and two TNF alpha mRNA bands were detected after stimulation: immature mRNA (4.8 kb) and mature TNF alpha mRNA (1.9 kb). Thus, the effects of boric acid observed in wound repair in vivo may be due to TNF alpha synthesis and secretion.

The recently cloned cytotoxic lymphocyte maturation factor [CLMF] also called NK cell stimulatory factor [NKSF] or interleukin-12 [IL-12] has been described as a growth factor for mature lymphoid cells. The present study investigated whether purified recombinant human IL-12 could stimulate CFU colony growth. Source of progenitor cells were peripheral blood cells depleted of adherent, CD2- and CD56-positive cells. RhIL-12 was investigated either alone or in combination with rhIL-3, rhIL-6 and rhGM-CSF. RhIL-12 alone did not support colony formation of myeloid or erythroid progenitors. RhIL-12 in combination with rhIL-3 increased the numbers of BFU-E and CFU-GM. No synergism or additive effect was seen with the combination of rhIL-12 and rhGM-CSF or rhIL-12 and rhIL-6. An additive increase in the number of granulocytic colonies was observed when rhIL-3, rhIL-6 and rhGM-CSF were used together with rhIL-12. Our result therefore suggest that, in addition to being a potent lymphopoietic stimulator, IL-12 acts synergistically with IL-3 in enhancing the sensitivity of hemopoietic progenitors to IL-3.

To gain additional informations on the role played by Natural Killer cells (NK) in the differentiation of human hematopoietic precursors, we have studied the effect of NK-cell depletion on the in vitro proliferation of hematopoietic cells. NK cells were depleted from blood mononuclear cells by FACS using anti CD3 and anti CD56 monoclonal antibodies. Depletion of NK cells suppressed CFU-GM up to 69% (P < 0,01), while no significant effect on either BFU-E and CFU-Mix growth was observed. To define the threshold of CD56+ cells required to support CFU-GM formation, NK cells were added to NK-depleted cells in a titrated fashion. Enhancement of CFU-GM colony growth was observed at NK/NK - depleted cells ratio of 0.15/1. A dose dependent suppression of CFU growth was observed at ratios ranging from 0.25/1 to 0.5/1. Addition of neutralizing antibodies against IL3 and GM-CSF abrogate the stimulating effect of NK cells. Our results suggest that cells with LGL morphology and NK markers play an important role in differentiation of myeloid precursors and exert a moderate influence on erythroid progenitors. The modulatory effect on hematopietic progenitors depend on the number of NK cells present in the mixed culture. © 1994 Wiley-Liss, Inc.