Evaluation of functional activity of thymus and bone marrow of newborns using the method of TREC and KREC quantitation

Abstract

IntroductionWith inborn errors of immunity, production of T- and B-lymphocytes is disrupted, as a result of which lymphopenia is developed, which is a life-threatening sign of a child's primary immunodeficiency. It is possible to evaluate functional activity of thymus and bone marrow for early detection of primary immunodeficiency using the TREC/KREC method. Materials and methodsWe have studied DNA from a DBS of 100 preterm infants gestating from 23.5 to 37.0 weeks by RQ-PCR. The number of TREC/KREC copies has been calculated using the formula: [1,000,000 × SQ TREC (KREC)/SQ ALB/2]. ResultsThe lowest number of TREC copies has been observed in the group of preterm infants 28.0 weeks or less TRECs-mediana – 1 × 103(3 × 102–3,8 × 103copies/106leukocytes), the lowest number of KREC copies has been observed in the group of children 29–32 weeks of gestation TRECs-mediana – 4.8 x103 (3.2–8.4 x103/106leukocytes). TREC copy numbers were significantly lower for preterm infants from 23.5 to 35.0 weeks’ gestation (p < 0.05) comparing to TRECs number of mature newborns. The number of KREC copies was significantly lower from 23.5 to 32.0 weeks of gestation (p < 0.05) comparing to full-term infants. Evaluation of TREC/KREC has been carried out in dynamics for very preterm infants with the lowest TREC and KREC rates upon reaching their gestational age of 37.0 weeks. With an increase in gestational age, the quantitative rate of TREC/KREC for children increased, which indicated normal neonatal lymphopoiesis and exclusion of genetically determined primary immunodeficiency. Obtaining low indicators in dynamics may indicate a violation of the bone marrow function, as well as the function of thymus, which requires an in-depth immunological study to identify genetically determined immunological disorders. ConclusionTREC and KREC can be used as markers of functional activity of thymus and bone marrow for newborns.