| BackgroundAnticardiolipin antibody(ACA)includes beta 2-glycoprotein Ⅰ(β2-GPⅠ)-dependent and β2-GPⅠ-independent forms.The former mainly exists in the patients with antiphospholipid antibody syndrome and other autoimmune diseases,and it could cause abnormal blood coagulation manifestations such as arterial and/or venous thrombosis and thrombocytopenia.β2-GPⅠ-independent ACA is almost found in infectious diseases patients and the ACA is not related to the aforementioned clinical manifestations.In addition,studies have stated that patients with certain infectious diseases may suffer from blood coagulation disorder,and the coagulation function of syphilis patients has not been reported.However,some recent studies have been reported that β2-GP Ⅰdependent ACA may exist in infectious diseases patients.Positive nontreponemal antibody is both in syphilis and biological false-positive(BFP)subjects,and the characteristics of ACA,which is the major component of nontreponemal antibody,as well as their blood coagulation remains to be further clarified.Thus,the present study aimed to determine the characteristics of ACA in the syphilis and BFP subjects,and to explore the association between the autoimmune antibody and blood coagulation status.MethodsIn total,675 subjects including 465 syphilis patients,146 BFP subjects and 64 APS patients,were enrolled,and their levels of serum β2-GPⅠ-dependent ACA IgA/IgG/IgM and anti-β2-GP ⅠIgA/IgG/IgM antibodies were detected using a novel chemiluminescence assay.Meantime,conventional blood coagulation indices were measured to analyze their associations with the antoantibodies including activated partial thromboplastin time(APTT),prothrombin time(PT),thrombin time(TT),fibrinogen concentration(FIB)and platelet counts.Besides,eight New Zealand male rabbits were selected to detect their serum β2-GPⅠ-dependent ACA by self-built ELISA,and the nontreponemal antibody were tested by venereal disease research laboratory(VDRL)simultaneously.ResultsThe positive rates of β2-GPⅠ-dependent ACA and anti-β2-GP antibody in the ⅠBFP and APS subjects were significantly elevated than those in the syphilis patients respectively(syphilis: 3.87%,1.08%;BFP: 22.60%,28.77%;APS: 32.81%,32.81%;P<0.001).There were no significant differences in positive autoantibody rates between BFP subjects and APS patients(P=0.119,P=0.556).Besides,there were no associations between the levels of positive β2-GPⅠ-dependent ACA and the rapid plasma regain(RPR)titers in syphilis and BFP subjects(P>0.05).The dominant β2-GPⅠ-dependent ACA and anti-β2-GP antibody isotypes identified Ⅰin the syphilis patients were IgM.While the key autoantibody isotypes identified in the BFP and APS subjects were both IgG,and the positive rates of IgA were also significant.Compared to the syphilis patients,BFP and APS subjects had longer APTTs(P<0.001)and PTs(P<0.001)but reduced FIB(P=0.022)and platelet counts(P<0.001).The APTTs were extended in syphilis,BFP and APS subjects with positive autoantibodies compared with those in the subjects with negative autoantibodies(P<0.05).β2-GPⅠ-dependent ACA could be induced by immunizing cardiolipin-bovine serum albumin in New Zealand male rabbits and keep the results of VDRL be positive partly.ConclusionsThe ACAs in syphilis patients and BFP subjects are heterogeneous.The syphilitic ACA is β2-GPⅠ-independent type,while β2-GPⅠ-dependent ACA constitutes a significant proportion in BFP subjects which close to that in the positive control APS patients.Meanwhile,β2-GPⅠ-dependent ACA might be one of the reasons for biological false-positive syphilis reaction.In addition,the consistency between β2-GPI-dependent ACA and ACA is extremely poor.Positive β2-GPⅠ-dependent ACA is independent of nontreponemal antibody titers.The β2-GPⅠ-dependent ACA and the ACA tested by nontreponemal antibody test are different.Furthermore,BFP subjects are more prone to blood coagulation disorder than syphilis patients,and theβ2-GPⅠ-dependent ACA and anti-β2-GP antibody Ⅰcould impact intrinsic coagulation cascades in these subjects. |
