Anti-Cardiolipin, Anti-Cardiolipin Plus Bovine, or Human β 2Glycoprotein-I and Anti-Human β 2Glycoprotein-I Antibodies in a Healthy Infant Population

Abstract

Background Pathogenic antiphospholipid antibodies studies are usually conducted on populations of adults. Studies involving normal children are scant. Methods Antibody reactivity against CL alone (true aCL), CL-complexed to bovine β 2GP-I (aCL-bovine β 2GP-I), or human (aCL-human β 2GP-I) β 2GP-I, or to phospholipid-free human β 2GP-I (anti-human β 2GP-I) was determined by ELISA in serum samples from 360 Mexican children ranging from 1 month through 8 years of age. Results Statistical analysis of variance and rankings of Kruskal-Wallis demonstrated no significant difference in all tested antibody activities between ages and genders of the study population. Values are presented as a percentile distribution included between 5 and 99, corresponding to the percentages of the studied population. Normal arbitrary units (AU) for IgG, IgA, and IgM true aCL that correspond to the 95 and 99 percentiles are as follows: 2.15 and 3.5; 2.35 and 5.0, and 3.15 and 4.5, respectively. IgG, IgA, and IgM aCL-bovine β 2GP-I activities are 2.6 and 5.0, 3.0 and 5.0, and 2.7 and 6.0 AU, respectively, while IgG activities of aCL-bovine and human β 2GP-I are 1.45 and 1.80, respectively. Normal values for IgG anti-human β 2GP-I are 1.85 AU. Conclusions While elevated serum levels of antibodies to CL and/or β 2GP-I have been associated with thrombotic and hematologic manifestations, the majority of reports deal with adult populations. We report the cut-off values (in AU, international PL units, and international units for β 2GP-I) of the specific serologic response of true aCL, aCL-bovine β 2GP-I, aCL-human β 2GP-I, and anti-human β 2GP-I in healthy Mexican children.