Interestingly, the anti-SS-A antibody level dropped to 16,439 U/mL (from 162,143 U/mL) 2 weeks after starting plasma exchange treatment, and dropped to 257 U/mL when the platelet count returned to normal range after the completion of plasma exchange treatment.
Anti-SS-A antibody has been reported to be associated with a subtype of lupus erythematosus, chilblain lupus erythematosus, which is characterized by erythematosus lesions induced by a cold, damp climate and positive anti-SS-A serology.
Abnormal immunoglobulins in these patients may contribute to the pathogenesis of acute TTP, since the abnormal immunoglobulins (such as anti-SS-A antibody) may interrupt the normal inhibition of platelet aggregation or inhibit the activity of vWF-cleaving protease.
Whether abnormal serologic findings such as anti-SS-A antibody play a role in triggering TTP is the subject of future study.
TABLE 1 Summary Data of SLE Patients With Serologic Abrnormalities and Acute TTP Serologic Reference Abnormality SLE Pregnancy Hess et al (14) Antiphospholipid antibody + - Dixit et al (15) C2 deficiency + + Cockerell and Lewis (16) Abnormally large forms of vWF + - Our report Anti-SS-A antibody + + Reference TTP Hess et al (14) + Dixit et al (15) + Cockerell and Lewis (16) - Our report + SLE = Systemic lupus erythematosus TTP = thrombotic thrombocytopenic purpura vWF = von Willebrand's factor.