Anticardiolipin and antinuclear antibodies in the adult healthy Omani individuals

Objective: To investigate the prevalence and normal versus abnormal levels of anticardiolipin antibodies (aCL) in a healthy adult population of Omanis and whether a correlation exists between aCL and antinuclear antibodies (ANA) in this Omani population. Methods: A total of 521 healthy Omani individuals (333 males and 188 females), aged between 17-54-years were investigated for the presence and quantities of anticardiolipin antibodies (immunoglobulin G (IgG)) and IgM isotypes using a conventional enzyme linked immunosorbent assay. Antinuclear antibodies were detected, in this group, using standard indirect immunofluorescence techniques. This study was conducted during the period 2002 through to 2003 at the Immunology Laboratories, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman. Results: The prevalence of aCL in the healthy Omani population was estimated to be 2.5% for IgG and 3.1% for IgM. The cut off points for IgG and IgM were determined for the whole population as 22.5 IgG phospholipid (GPL) units and 15.7 IgM phospholipid (MPL) units, using the mean plus 5 standard deviations. Using these cut off values, aCL were not detected in the majority of individuals (97%) and in the remaining 3%, the levels were not very high. There was no significant difference between the levels of aCL in either the male or female groups and no significant correlation for the presence of aCL with the age in this studied population. Antinuclear antibodies were detected in 76/521 (14.6%) of the population studied, with some individuals (0.8%) showing titers of 1:640, but there was no association with aCL. Conclusion: Although, ANA is present in this healthy Omani population at high frequency and in some individuals at high levels, high levels of aCL do not occur and their presence may be an indicator of autoimmune mediated pathology.