This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunity, Subject name: Pathology
Most common antibody in sjogren syndrome 
Select and explain. 
A. Anti-DNA topoisomerase, B. Anti-Centromere, C. Anti-RNA polymerase, D. Anti-Ribonucleoprotein
D: Anti-Ribonucleoprotein
Answer: D: Anti-Ribonucleoprotein 
Explanation: Ans. (d) Anti-Ribonucleoprotein(Ref: Robbins 9th/pg218; 8th/pg213)Autoantibodies in Sjogren's syndrome:Anti SS-A (Ro) and SS-B (La) Q: Most important, present in 90% patients;High titers of Anti SS-A - more likely to have early disease onset, longer disease duration, and extra- glandular manifestations (eg cutaneous vasculitis and nephritis)Rheumatoid factor (an antibody reactive with self IgG): in 75% Q, ANA: in 50% to 80%