This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Following all are antigens for antiphospholipid antibody except ? 
Select and explain. 
A. Prothrombin, B. Erythrocyte membrane, C. Phospholipid, D. Beta 2 glycoprotein
B: Erythrocyte membrane
Answer: B: Erythrocyte membrane 
Explanation: Ans. is 'b' i.e., Erythrocyte membraneAntiphospholipid syndromeAntiphospholipid syndrome develops in patients expressing antibodies to anionic phospholip. i.e., antiphospholipid antibody or lupus anticoagulant.These antibodies not only act against phospholipid, as it was believed, but also against epitopes of plasma proteins.A variety of protein have been implicated; 2-glycoprotein paicularly impoant, i.e., antiphospholipid antibody is directed against the phospholipid - 2-glycoprotein complex.Other proteins are prothrombin, protein S, protein C, annexin V.Three antibody are paicularly impoant :Antiphospholipid (anti Cardiolipin)Anti-2-glycoprotein (i.e., against 2-glycoprotein component of phosphilipid-2-glycoprotein complex).A nti-prothrombin