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.
Autoantibodies have been known to be detected during pregnancy. The occurrence of autoantibodies during pregnancy was studied in a group of 146 healthy pregnant women from Jan-March 1995. Serum samples were tested for antinuclear (ANA), anti-ds DNA, anti-mitochondrial, anti-smooth muscle and anti-parietal cell antibodies employing the technique of indirect immunofluorescence. Sera from 66 non-pregnant women were used as controls. Among the pregnant group, 2 (1.4%) were found to have ANA positivity in comparison to none in the control group. This difference was found to be not statistically significant. Only 1 (0.7%) was positive for anti-mitochondrial antibody in the pregnant group compared to one in the control group (p > 0.05). However, anti-ds DNA, anti-smooth muscle and anti-parietal cell antibodies were not detected in both groups. All those positive for autoantibodies were in their 2nd trimester. When these cases were followed-up at the end of their pregnancy, none had complicated pregnancies nor infant abnormalities. Our findings suggest that (a) the occurrence of autoantibodies in pregnant women was not significantly different from non-pregnant controls and that (b) maternal autoantibodies did not appear to cause complications during pregnancy or infant morbidity.