Induction of Adenovirus Specific T-Cells in Response to 15-Mer Peptides in Cord Blood

Abstract

Human adenovirus (HAdV) infections are a serious life-threat in haematopoietic stem cell transplantation (HSCT) patients, particularly in children. In recent years, umbilical cord blood transplants (UCBT) emerged as an alternative stem cell source. The advantages are the rapid availability of donor cells, the possibility of using HLA-mismatched transplants and a lower risk of graft versus host disease. However, the immune response after UCBT is often delayed, leading to a higher risk of viral infections. Because no effective antiviral medication exists for severe HAdV infection adoptively transfer of HAdV specific T-cells from cord blood may be a promising treatment. The aim of this study was to see if it was possible to induce HAdV specific T-cells in response to five recently detected 15-mer peptides ( Haveman LM, Int. Imm. 2006), a pool of these five peptides or complete inactivated HAdV (MOI 10). Mitogen Concovalin A ( ConA) was used as control. Cord blood mononuclear cells (CBMC) derived from 34 uncomplicated full term deliveries were isolated and cultured with the different antigens. Proliferation expressed as Stimulation Index (SI) was determined. A SI>1.7 was seen as positive. In 14 neonates a response to in total 36 of the 5 different HAdV peptides could be seen and in 7 of them also a response to the pool of the peptides. Only in 3 neonates a response to complete HAdV could be detected (Figure 1). To induce HAdV specific T-cells CBMCs of 20 neonates were cultured with the different HAdV antigens in addition of interleukin 2 (40IU/ml) for 7 days. By using FACS analysis the upregulation of the activation markers CD25 and CD69 could be detected in response to the HAdV peptides (n=41) or to the complete HAdV (n=26). Induced HAdV specific T-cells expressed the cytotoxins IFN□, TNFα, perforin and granzyme B, produced by CD8+ T-cells, but in higher extent by CD4+ T-cells. This indicates that induced HAdV specific T-cells play an essential role in killing HAdV infections. No clear correlation could be seen between proliferation and the production of the cytotoxins. The induction of a specific immune response to HAdV peptides in cord blood is an important step towards adoptive therapy. [Display omitted]