Reconstitution of CMV-specific T-cells following adoptive T-cell immunotherapy and haematopoietic stem cell transplantation

This thesis investigated reconstitution of CMV-specific T-cells in two cohorts of HSCT patients and studied the potential role of Tumour Necrosis Factor Receptor 2 (TNFR2) in regulation of CMV-specific T-cell expansion post HSCT. The first cohort included patients of a randomized phase II trial of adoptive cellular therapy for CMV-specific CD8\(^+\) T-cells. Cellular therapy resulted in earlier and greater expansion of CMV-specific CD8\(^+\) T cells and also reconstitution of CMV-specific CD4\(^+\) and non-infused CMV-specific CD8\(^+\) T-cells. The number of infused therapeutic T-cells and circulating levels of Alemtuzumab were found to influence immunotherapy. Additionally, reconstitution of CMV-specific CD4\(^+\) T-cells was studied using HLA-class II tetramers. CMV-specific CD4\(^+\) T-cell count of >0.7x10\(^3\)/ml was found to protect from recurrent CMV reactivation. One third of specific CD4\(^+\) T-cells were perforin and granzyme-B positive indicating cytotoxic potential, whilst the majority expressed T-bet. Expression of CD57 molecule on CD4\(^+\) T-cells was demonstrated as a potential biomarker of immune response to CMV. Also, distinct cytokine receptor expression patterns in naïve versus memory T-cells were observed. The results showed rapid decrease in IL-6R and increase in expression of TNFR2 after T-cell differentiation from naïve to effector cells and engagement of TNFR2 led to the apoptosis of CMV-specific T-cells