The prevalence of antinuclear, anti-dsDNA, anti-Sm and anti-RNP antibodies in a group of healthy blood donors

We studied the prevalence of antinuclear (ANA), anti-double stranded DNA (dsDNA), anti-Sm and anti-RNP antibodies in a group of 93 blood donors (age range: 18-58 years). Antinuclear and anti-ds DNA antibodies were detected by immunofluorescence (IF) using HEp2 cells and Crithidia luciliae as substrates, respectively, while anti-Sm and anti-RNP antibodies were assayed by ELISA. ANA was found in 6.5% while anti-dsDNA antibodies were not detected in any of the subjects. The 98th percentile was used as cut off where values greater than 0.651 for anti-Sm and 0.601 for anti-RNP antibodies were taken to be positive. This gives a frequency of 1.1% for both antibodies. There was no significant association of antibody positivity with sex or race. We conclude that certain autoantibodies are present in low titres in the normal Malaysian Individuals, at a different frequency compared to other studies probably due to genetic, ethic or environmental factors.