title: Acquired activated protein C resistance is associated with lupus anticoagulants and thrombotic events in pediatric patients with systemic lupus erythematosus.
abstract: Acquired activated protein C resistance (APCR) has been hypothesized as a possible mechanism by which antiphospholipid antibodies (APLAs) cause thrombotic events (TEs). However, available evidence for an association of acquired APCR with APLAs is limited. More importantly, an association of acquired APCR with TEs has not been demonstrated. The objective of the study was to determine, in pediatric patients with systemic lupus erythematosus (SLE), whether (1) acquired APCR is associated with the presence of APLAs, (2) APCR is associated with TEs, and (3) there is an interaction between APCR and APLAs in association with TEs. A cross-sectional cohort study of 59 consecutive, nonselected children with SLE was conducted. Primary clinical outcomes were symptomatic TEs, confirmed by objective radiographic tests. Laboratory testing included lupus anticoagulants (LAs), anticardiolipin antibodies (ACLAs), APC ratio, protein S, protein C, and factor V Leiden. The results revealed that TEs occurred in 10 (17%) of 59 patients. Acquired APCR was present in 18 (31%) of 58 patients. Acquired APCR was significantly associated with the presence of LAs but not ACLAs. Acquired APCR was also significantly associated with TEs. There was significant interaction between APCR and LAs in the association with TEs. Presence of both APCR and LAs was associated with the highest risk of a TE. Protein S and protein C concentrations were not associated with the presence of APLAs, APCR, or TEs. Presence of acquired APCR is a marker identifying LA-positive patients at high risk of TEs. Acquired APCR may reflect interference of LAs with the protein C pathway that may represent a mechanism of LA-associated TEs. (Blood. 2001;97:844-849)
authors.affiliation: Hamilton Civic Hospitals Research Centre, Hamilton, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Male
authors.forename: L
authors.initials: L
authors.lastname: Mitchell
authors.forename: J
authors.initials: J
authors.lastname: Julian
authors.forename: P
authors.initials: P
authors.lastname: Vegh
authors.forename: P
authors.initials: P
authors.lastname: Joshua
authors.forename: M
authors.initials: M
authors.lastname: Adams
authors.forename: M
authors.initials: M
authors.lastname: David
authors.forename: M E
authors.initials: ME
authors.lastname: Andrew
mesh_terms: D020016:Activated Protein C Resistance / Q000097:blood / Q000209:etiology*; D000293:Adolescent; D000328:Adult; D017153:Antibodies, Anticardiolipin / Q000097:blood*; D001327:Autoimmune Diseases / Q000097:blood / Q000150:complications*; D001779:Blood Coagulation Factors / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D016167:Integrin alphaXbeta2 / Q000032:analysis; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000150:complications*; D008297:Male; D008954:Models, Biological; D011446:Prospective Studies; D011486:Protein C / Q000032:analysis; D017293:Protein S / Q000032:analysis; D011859:Radiography; D012189:Retrospective Studies; D013923:Thromboembolism / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D019851:Thrombophilia / Q000097:blood / Q000209:etiology*; D014463:Ultrasonography
chemical_list: D017153:Antibodies, Anticardiolipin; D001779:Blood Coagulation Factors; D016167:Integrin alphaXbeta2; D016682:Lupus Coagulation Inhibitor; D011486:Protein C; D017293:Protein S