ABSTRACT
Interleukin-7 is a cytokine essential for T cell homeostasis. IL-7 binds to cellular IL-7 receptors in competition with a soluble form of the receptor (sIL-7Rα). We hypothesized that altered sIL-7Rα levels may cause adverse outcomes in patients undergoing HSCT. In parallel, we investigated the impact of the IL-7Rα SNP rs6897932, which has been associated with release of IL-7R. The sIL-7Rα levels decreased during HSCT (from 114ng/ml before to 48ng/ml at day +14 (P<0.0001)). This pattern was inversely mirrored by IL-7. The IL-7/sIL-7Rα ratio at day +14 was significantly higher in patients developing grades II-IV aGVHD (OR=4.3, P=0.026). Furthermore, donor carriage of the rs6897932 T allele was associated with reduced sIL-7Rα levels, increased risk of grades II-IV aGVHD (OR=2.4, P=0.055) and increased transplant-related mortality (CC=4.5%, CT=21.4% and TT=27.3%, P=0.0037). In conclusion, this study suggests an impact of sIL-7Rα levels and rs6897932 donor genotype on alloreactivity and outcome after HSCT.
Subject(s)
Graft vs Host Disease/immunology , Hematopoietic Stem Cell Transplantation , Interleukin-7 Receptor alpha Subunit/immunology , Interleukin-7/immunology , Leukemia/therapy , Lymphoma, Non-Hodgkin/therapy , Myelodysplastic-Myeloproliferative Diseases/therapy , Acute Disease , Adolescent , Adult , Aged , Child , Child, Preschool , Female , Graft vs Host Disease/epidemiology , Humans , Infant , Male , Middle Aged , Mortality , Polymorphism, Single Nucleotide , T-Lymphocytes/immunology , Thrombocythemia, Essential/therapy , Transplantation, Homologous , Young AdultABSTRACT
BACKGROUND: IL-7 is an essential cytokine in T-cell development and homeostasis. It binds to the IL-7R receptor, a complex of the IL-7Ralpha (CD127) and common gamma (CD132) chains. There is significant interest in evaluating the expression of CD127 on human T-cells as it often decreased in medical conditions leading to lymphopenia. Previous reports showed the usefulness of CD127 as a prognostic marker in viral infections such as HIV, CMV, EBV and HCV. A soluble CD127 (sCD127) is released in plasma and may contribute to disease pathogenesis through its control on IL-7 activities. Measuring sCD127 is important to define its role and may complement existing markers used in lymphopenic disease management. We describe a new quantitative assay for the measurement of sCD127 in plasma and report sCD127 concentrations in healthy adults. METHODOLOGY/PRINCIPAL FINDINGS: We developed a quantitative bead-based sCD127 capture assay. Polyclonal CD127-specific antibodies were chosen for capture and a biotinylated monoclonal anti-CD127 antibody was selected for detection. The assay can detect native sCD127 and recombinant sCD127 which served as the calibrator. The analytical performance of the assay was characterized and the concentration and stability of plasma sCD127 in healthy adults was determined. The assay's range was 3.2-1000 ng/mL. The concentration of plasma sCD127 was 164+/-104 ng/mL with over a log variation between subjects. Individual sCD127 concentrations remained stable when measured serially during a period of up to one year. CONCLUSIONS/SIGNIFICANCE: This is the first report on the quantification of plasma sCD127 in a population of healthy adults. Soluble CD127 plasma concentrations remained stable over time in a given individual and sCD127 immunoreactivity was resistant to repeated freeze-thaw cycles. This quantitative sCD127 assay is a valuable tool for defining the potential role of sCD127 in lymphopenic diseases.
