Background: Anti-Ro antibody may directly react against either Ro60 or Ro52 or both antigens. To be more applicable for routine laboratory practice, the specific antigen type for antibody detection should be identified before test application.
Objective: Investigate the prevalence of 60 kDa and 52 kDa Ro/SS-A antibodies in Thai patients’ sera in Siriraj Hospital.
Material and Method: Specimens for anti-Ro were requested between June and December 2005. They were tested with EUROLINE test kit for prevalence determination. The principle of the test is a qualitative in-vitroassay that contains test strips coated with parallel lines of 14 highly purified antigens. Of 84 specimens requested for anti-Ro antibody, 76 were collected and tested with the EUROLINE test kits and eight were excluded due to inadequacy.
Results: The prevalence of anti-Ro60 and anti-Ro52 of all sera tested for anti-Ro by EUROLINE test kit were 30% (95% CI: 20-40%) and 26% (95% CI: 16-36%), respectively; and, those in anti-Ro positive Thai sera were 82% (95% CI: 68-96%) and 71% (95% CI: 54-88%), respectively. The prevalence of anti-Ro52 alone in anti-Ro positive Thai sera and all specimens requested for anti-Ro was about 18% (95% CI: 4-32%) and 7% (95% CI: 1-13%), respectively. The agreement and Kappa value between the two methods were 0.9 and 0.77, respectively. The study suggests that the test for anti-Ro detection should provide both Ro 60 and Ro 52 antigens.
Conclusion: The prevalence of both anti-Ro 60 and anti-Ro 52 were quite common, therefore, the test for this specific antibody should provide both antigens for antibody detection.

Keywords: Prevalence, Anti-Ro, Anti-Ro 60, Anti-Ro 52