In adults, one-haplotype-mismatched haematopoietic SCT (haploidentical HSCT) is associated with slow immune recovery due to decaying thymic function and extensive T-cell depletion of the graft. Although essential for preventing GVHD, T-cell depletion underlies the major reasons for transplant failure: leukemia relapse and infections, with infection-related mortality accounting for about 40% of non-leukemic deaths. Adoptive T-cell therapy would be helpful for these patients but to administer it without causing GVHD, alloreactive T cells need to be eliminated from donor T lymphocytes before infusion. In a preclinical study, to address this problem, we determined the efficacy of photodynamic purging of alloreactive T cells, by investigating combinations of parameters in order to achieve maximum allodepletion, preservation of T-regulatory cells and of pathogen and leukemia-specific T-cell responses in donor-vs-recipient MLR. We also needed to identify an optimal method to quantify the Ag-specific T-cell repertoires. Optimal procedures were identified. In particular, we compared limiting-dilution analyses (LDA) of proliferating T cells with H(3)-thymidine incorporation by bulk T cells and with flow cytometry CD25 expression, which is accepted as a T-cell activation marker. This study demonstrated that LDA is a reliable, predictable and sensitive method for measuring alloreactive, pathogen- and leukemia-specific T-cell frequencies.
Optimizing a photoallodepletion protocol for adoptive immunotherapy after haploidentical SCT / K. Perruccio ; F. Topini ; A. Tosti ; A. Carotti ; E.Burchielli ; L.Ruggeri ; A.Mancusi ; E.Urbani ; F.Aversa ; MF. Martelli ; A. Velardi.. - In: BONE MARROW TRANSPLANTATION. - ISSN 0268-3369. - 47:9(2012), pp. 1196-1200. [10.1038/bmt.2011.237]