Simultaneous quantification of recent thymic T-cell and bone marrow B-cell emigrants in patients with primary immunodeficiency undergone to stem cell transplantation

Peripheral accumulation of newly produced T and B lymphocytes in natalizumab-treated multiple sclerosis patients

“…Quantification of TRECs, KRECs, average number of B-cell divisions, and TCR repertoire analysis KRECs and TRECs were simultaneously quantified, together with the reference gene, a segment of TCR constant alpha chain (TCRAC), by a duplex quantitative Real-Time PCR performed on the 7500 Fast Real-Time PCR. The sequences and the quantity of primers and probes used for the assay, as well as the amplification schedule, were described elsewhere [12,13]. KREC, TREC, and TCRAC copy numbers have been calculated by extrapolating the respective sample quantities from the standard curve obtained by tenfold dilutions (from 10 6 to 10) of a linearized plasmid DNA, containing three inserts corresponding to fragments of KRECs, TRECs and TCRAC.…”

“…Furthermore, the different expression of VLA-4 on lymphocyte subpopulations, with its basal levels higher on B than on T cells, on CD8 + than on CD4 + T cells, and on memory than on naïve cells [10,11] could also imply that natalizumab treatment can differentially influence the homeostasis of lymphocyte subsets. To verify these possibilities, we monitored the changes in the number of T and B lymphocytes recently released from thymus and BM in patients treated with natalizumab by quantifying the number of T-cell receptor (TCR) excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs) [12,13]. KRECs and TRECs are DNA excision products generated during B-and T-cell receptor gene rearrangements.…”

“…KRECs and TRECs are DNA excision products generated during B-and T-cell receptor gene rearrangements. Because they do not replicate when cells proliferate in the periphery, and are lost when the cells die, their quantification is considered a reliable estimate of the amount of newly produced B and T lymphocytes [12,13]. The composition of peripheral lymphocyte pool was studied by phenotyping T-and B-cell subsets, and by analyzing the heterogeneity of the TCR repertoire [12] and the replication history of B lymphocytes [14].…”

Newborn Screening for Severe Combined Immunodeficiency in Taiwan

“…A combined TREC/KREC approach has been able to identify patients with severe B cell disorders such as X-linked agammaglobulinemia [30] and delayed-onset ADA deficiency [36]. To identify other forms of primary immunodeficiency, such as X-linked agammaglobulinemia (XLA) [37][38][39], we have tested the feasibility of performing a KREC assay as previous described [40]. The KREC assay could accurately indicate SCID with a RAG1 mutation and other situations such as newborns with pancytopenia or B lymphopenia, but the correlation in newborns with a IL2RG mutation was low.…”

The Different Extent of B and T Cell Immune Reconstitution after Hematopoietic Stem Cell Transplantation and Enzyme Replacement Therapies in SCID Patients with Adenosine Deaminase Deficiency

“…In the present retrospective longitudinal study, we compared the extent of immune recovery in ADA-deficient patients who received HSCT or were treated with PEG-ADA. The evaluation of the release of new B and T cells from the bone marrow and the thymus was performed using a duplex quantitative real-time PCR protocol that combines the well-established and widely used method of measuring thymic function, the TCR excision circle (TREC) assay (16), and the more recently proposed k-deleting recombination excision circle (KREC) assay (17)(18)(19).…”