title: Recombinant staphylokinase variants with altered immunoreactivity. IV: Identification of variants with reduced antibody induction but intact potency.
abstract: BACKGROUND
  The thrombolytic potency and antibody induction of selected variants of recombinant staphylokinase (SakSTAR), including SakSTAR(K74) with Lys74, SakSTAR(E75) with Glu75-, SakSTAR(EER) with Glu38, Glu75, and Arg77, and SakSTAR(K74ER) with Lys74, Glu75, and Arg77 replaced by Ala, were studied.
  
  
  RESULTS
  In rabbits, SakSTAR(74) and SakSTAR(EER) elicited significantly less circulating neutralizing activity than SakSTAR and SakSTAR(E75) (P = .005 and P = .0002 versus SakSTAR, respectively). In baboons, SakSTAR(K74) induced significantly fewer antibodies than wild-type SakSTAR (P < .05). Intra-arterial administration in patients with peripheral arterial occlusion of SakSTAR(K74) (n = 11) or SakSTAR(K74ER) (n = 6) induced significantly fewer circulating neutralizing antibodies [median values and interquartile ranges, 20 (3.8 to 26) and 2.4 (0.2 to 59) micrograms compound neutralized/mL plasma after 3 to 4 weeks (P = .01 and P = .035 versus SakSTAR, respectively)] than SakSTAR (n = 9) [median value and interquartile range, 93 (24 to 110) micrograms compound neutralized/mL plasma]. Overt neutralizing antibody induction (> 10 micrograms compound neutralized/mL plasma) occurred in all 9 patients given wild-type SakSTAR, in 6 of the 11 SakSTAR(K74ER) patients (P = .038 versus SakSTAR), and in 2 of the 6 SakSTAR(K74ER) patients (P = .011 versus SakSTAR).
  
  
  CONCLUSIONS
  SakSTAR(K74), a variant of recombinant staphylokinase with a single substitution of Lys74 with Ala, and SakSTAR(K74), with Lys74, Glu75, and Arg77 substituted with Ala, have intact thrombolytic potencies but induce significantly less antibody formation in patients.
authors.affiliation: Center for Molecular and Vascular Biology, University of Leuven, Belgium. desire.collen@med.kuleuven.ac.be
authors.forename: D
authors.initials: D
authors.lastname: Collen
authors.forename: L
authors.initials: L
authors.lastname: Stockx
authors.forename: H
authors.initials: H
authors.lastname: Lacroix
authors.forename: R
authors.initials: R
authors.lastname: Suy
authors.forename: S
authors.initials: S
authors.lastname: Vanderschueren
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D000906:Antibodies / Q000276:immunology*; D000917:Antibody Formation; D001157:Arterial Occlusive Diseases / Q000188:drug therapy; D005343:Fibrinolytic Agents / Q000276:immunology*; D014644:Genetic Variation; D006801:Humans; D007114:Immunization; D007269:Injections, Intra-Arterial; D008666:Metalloendopeptidases / Q000235:genetics* / Q000276:immunology* / Q000627:therapeutic use; D008875:Middle Aged; D010215:Papio; D011817:Rabbits; D011994:Recombinant Proteins
chemical_list: D000906:Antibodies; D005343:Fibrinolytic Agents; D011994:Recombinant Proteins; D008666:Metalloendopeptidases; C022653:auR protein, Staphylococcus aureus