ROLE OF BIOLOGICAL RESPONSE MODIFIERSIN THE REGULATION OF THROMBOPLASTIN SYNTHESIS IN MONOCYTES AND ENDOTHELIAL CELLS
A rabbit polyclonal antibody which was monospecific for thromboplastin (TP) apoprotein from human brain according to a number of criteria was used to screen two human placenta cDNA libraries in the expression vector Agtll, one randomly primed and one oligo-dT primed, by the method of Young and Davis. 23 positive clones expressing TP related antigen were isolated and plaque purified. DNA from the different clones was isolated and the TPcDNA inserts released by EcoRl digestion. The inserts could be classified into11 size classes ranging from approx. 300-1100 base pairs.The largest insert (1100 bp) was subcloned intothe plasmid vector pGEM-1. When the nick-translated plasmid (pTP4-l) was used as a probe to screen the phage clones by slot blot hybridization all the 23clones hybridized to the 1100 bp insert. A XgtllTP4 lysogen expressed B-galactosidase- TP4 fusion peptide upon IPTG induction as shown by immunobinging studied using two different antibodies to TP apoprotein: the rabbit antibody originally used to screen the libraries and an antibody raised in goat against human brain TP purified by affinity chromatography on a Factor Vll-antiVII-agarose column.Cytokines mediate many of the cellular interactions in the inflammatory and immune response systems and have a variety of actions. We have investigated the effect of rIL-1a/$,rIL-2, rlFNa/y and rTNFa on thromboplastin synthesis (TPL) in monocytes (M) and human umbilical vein endothelial cells (HUVEC). Recombinant IL- 1a and IL-16 both induced a dose dependent increase in TPL activity of monocyte (8-fold) and HUVEC cultures (15-fold) at 6h. The increase levelled off at interleukinconcentrations of 50-100u/ml. Recombinant IL-2 at 50u/ml induced a 5-fold rise in monocytes TPL. The effect of rIL-2 on HUVEC TPL synthesis at 6 h was smaller than on monocytes but still clearly significant at dose dependent. Recombinant IFN-Y (10 -10 u/ml) increased.TPL activity in HUVEC at 6h and 16 h in adose dependent manner, whereas no effect of rIFN-Y and IFN-a (1-10 u/ml) on M TPL was seen. When LPS (5pg/ml) was used to induce TPL synthesis, additional stimulation with rIFN-Y further enhanced HUVEC TPL activity, but decreased M TPL activity. Recombinant IFNa also decreased LPS induced TPL synthesis in M andhad no effect on HUVEC TPL. Recombinant TNFa (0.3x104u/ml) increased HUVEC TPL 7-fold at 6h. There wasno effect on M TPL synthesis. No endotoxin was detected in any of these preparations. CONCLUSIONS: Some biological response modifiers induced thromboplastin synthesis in monocytes (IL-ia, IL-13, IL-2) and in human umbilical vein endothelial cells (IL-ia, IL-18, IL-2, TNFa and IFNY). Some had no direct effect on TPL synthesis but inhibited the response to monocytes to other thromboplastin-inducing agents like LPS (IFNa and IFNY).