Abstract

Down syndrome (chromosome 21 trisomy) is the most frequent chromosomal disorder with diverse clinical signs. Many of these are due to dysfunction of the immune system.
Aim. To study the prevalence of common autoantibodies in 145 Down syndrome patients (aged 1 months to 45 years; 68 female) and to compare these data to autoantibody prevalence in age and sex matched controls; to analyse peripheral blood cellular immunity characteristics in comparison to controls in order to find out possible causes of autoimmunity predisposition in Down syndrome patients.
Methods. Indirect immunofluorescence for detection of nuclear, mitochondrial, reticulin, gastric parietal cell, thyroid microsomal and pancreatic islet cell antibodies, immunoblot for detection of cytochrome P450 21-hydroxylase antibodies, and flow cytometry with fluorochrome marked monoclonal antibodies for peripheral blood lymphocytes phenotyping.
Results. In the younger Down syndrome patient group (age below 15 years) autoantibodies were detected in single cases. Patients 15 years of age or older had a significantly higher prevalence of  nuclear and reticulin antibodies than the controls (P = 0.0001 and P <0.0001, respectively). Mitochondrial antibodies and antibodies to cytochrome P450 21-hydroxylase were not found in any of the 145 Down syndrome patients. Among cellular immunity characteristics, the most prominent difference was revealed in the amount of T lymphocytes with the memory (CD45RO+)  phenotype being much higher in Down syndrome patients compared to the controls (P = 0.0005).
Conclusion. Down syndrome patients may have several common autoantibodies among which some have significantly higher prevalence compared to age and sex matched controls. Down syndrome patients have more memory T lymphocytes in peripheral blood, witch might be a sign of propensity to develop such autoantibodies.