Anticardiolipin and anti‐β2 glycoprotein I antibodies in sera of 61 apparently healthy children at regular preventive visits

Objectives. To determine anticardiolipin (aCL) and anti‐β2 glycoprotein I antibodies (anti‐β2GPI) in apparently healthy children and express the cut‐off levels in concentrations of monoclonal antibodies, and to compare the mean values and frequencies of aCL and anti‐β2GPI in children with those in blood donors. Methods. Blood samples were collected from 29 preschool children and 32 adolescents during their routine preventive follow‐up visits. The control group consisted of 52 blood donors. aCL and anti‐β2GPI were assayed by an ELISA method. Two monoclonal β2GPI‐dependent aCL (HCAL and EY2C9) were used as calibrators. Results. The estimated cut‐off values for immunoglobulin G (IgG) and immunoglobulin M (IgM) aCL, expressed in concentrations of monoclonal antibodies and standardized international units (GPL/MPL units), were 13.9 ng/ml (7.6 GPL) and 33.1 ng/ml (3.3 MPL) for preschool children, 13.5 ng/ml (7.2 GPL) and 36.9 ng/ml (4.0 MPL) for adolescents, and 14.4 ng/ml (8.0 GPL) and 42.6 ng/ml (5.1 MPL) for blood donors. No statistically significant differences in the mean values for IgG and IgM aCL were found between the age groups. The mean value of IgA aCL was significantly higher in blood donors than in preschool children and adolescents (P