EFFECTS OF SYNTHETIC OLIGONUCLEOTIDES ON HUMAN-COMPLEMENT AND COAGULATION

Oligodeoxynucleotide phosphorothioates (PS-oligos) are being studied a s novel therapeutic agents based on their ability to inhibit gene expr ession. Preclinical studies produced unanticipated complement and coag ulation effects in monkeys receiving high-dose PS-oligo. In the presen t in vitro studies, PS-oligo inhibited normal human blood clotting as well as subsequent assays for prothrombin fragment PF1+2 and hemolytic complement. PS-oligo treatment of normal donor plasma produced concen tration-dependent prolongations of clotting times, with the activated partial thromboplastin time more sensitive than prothrombin time or th rombin clotting time. PS-oligo treatment of normal donor serum similar ly reduced hemolytic complement activity in a concentration-dependent manner. Reduced hemolysis correlated with increased levels of compleme nt fragment C4d. The anti-heparin drug protamine sulfate inhibited in vitro effects of PS-oligo in both complement and coagulation assays, s uggesting that charged residues in internucleotide linkages of PS-olig o mediated the observed activities. Therefore, oligonucleotides with v arying internucleotide linkages, nucleotide sequence, or secondary str ucture were compared. Both complement and coagulation effects appeared to be independent of nucleotide sequence but were strongly related to the nature of internucleotide linkages. Several of these modified oli gonucleotides have been shown previously to retain potent antisense ac tivity and thus may represent viable alternatives for antisense therap eutics. (C) 1997 Elsevier Science Inc.