Comparison of major lymphocyte subpopulations and recent thymic emigrants in patients with ataxia telangiectasia and age-matched healthy groups.

BACKGROUND Ataxia telangiectasia (A-T) is a genetic disorder caused by the homozygous mutation of the A-T mutated gene. It is frequently associated with variable degrees of cellular and humoral immunodeficiency. However, the immune defects in A-T patients are not well characterized. To the best of our knowledge, no studies have focused on the major lymphocyte subpopulations and recent thymic emigrants of A-T patients in comparison with age-matched healthy controls. METHODS Following the European Society for Immunodeficiencies criteria, 17 patients diagnosed with A-The, and 12 age-matched healthy children were assigned to the study. Both patients and healthy controls were grouped as 1-5, 6-10, 11-15, and 15+ years. By using a flow cytometer, major lymphocyte subpopulations and CD4+CD45RA+CD31+ recent thymic emigrants were determined as percentage and absolute cell numbers and compared. RESULTS No significant differences in all lymphocyte subpopulations were observed between the age groups of A-T patients. Compared to the healthy controls, there was a decrease in T cells, effector memory T4 cells, B cells, naïve B cells, naïve T4 cells, switched B cells, and recent thymic emigrants and an increase in active T8 cells and non-switched B cells in the percentage and absolute number of some cell populations in the A-T group. CONCLUSIONS This study showed that effector functions in some cell lymphocyte populations were decreased in A-T patients.