Unsaturated fatty acids (UFA) are crucial for T-cell effector functions, as they can affect the growth, differentiation, survival, and function of T cells. Nonetheless, the mechanisms by which UFA... Show moreUnsaturated fatty acids (UFA) are crucial for T-cell effector functions, as they can affect the growth, differentiation, survival, and function of T cells. Nonetheless, the mechanisms by which UFA affects T-cell behavior are ill-defined. Therefore, we analyzed the processing of oleic acid, a prominent UFA abundantly present in blood, adipocytes, and the fat pads surrounding lymph nodes, in CD4+ T cells. We found that exogenous oleic acid increases proliferation and enhances the calcium flux response upon CD3/CD28 activation. By using a variety of techniques, we found that the incorporation of oleic acid into membrane lipids, rather than regulation of cellular metabolism or TCR expression, is essential for its effects on CD4+ T cells. These results provide novel insights into the mechanism through which exogenous oleic acid enhances CD4+ T-cell function. Show less
Chimeric antigen receptor (CAR) T cell therapies have resulted in profound clinical responses in the treatment of CD19-positive hematological malignancies, but a significant proportion of patients... Show moreChimeric antigen receptor (CAR) T cell therapies have resulted in profound clinical responses in the treatment of CD19-positive hematological malignancies, but a significant proportion of patients do not respond or relapse eventually. As an alternative to CAR T cells, T cells can be engineered to express a tumor-targeting T cell receptor (TCR). Due to HLA restriction of TCRs, CARs have emerged as a preferred treatment moiety when targeting surface antigens, despite the fact that functional differences between engineered TCR (eTCR) T and CAR T cells remain ill-defined. Here, we compared the activity of CAR T cells versus engineered TCR T cells in targeting the B cell malignancy-associated antigen CD20 as a function of antigen exposure. We found CAR T cells to be more potent effector cells, producing higher levels of cytokines and killing more efficiently than eTCR T cells in a short time frame. However, we revealed that the increase of antigen exposure significantly impaired CAR T cell expansion, a phenotype defined by high expression of coinhibitory molecules and effector differentiation. In contrast, eTCR T cells expanded better than CAR T cells under high antigenic pressure, with lower expression of coinhibitory molecules and maintenance of an early differentiation phenotype, and comparable clearance of tumor cells. Show less
Since multiple different T-cell receptor (TCR) sequences can bind to the same peptide-MHC combination and the number of TCR-sequences that can theoretically be generated even exceeds the number of... Show moreSince multiple different T-cell receptor (TCR) sequences can bind to the same peptide-MHC combination and the number of TCR-sequences that can theoretically be generated even exceeds the number of T cells in a human body, the likelihood that many public identical (PUB-I) TCR-sequences frequently contribute to immune responses has been estimated to be low. Here, we quantitatively analyzed the TCR-repertoires of 190 purified virus-specific memory T-cell populations, directed against 21 epitopes of Cytomegalovirus, Epstein-Barr virus and Adenovirus isolated from 29 healthy individuals, and determined the magnitude, defined as prevalence within the population and frequencies within individuals, of PUB-I TCR and of TCR-sequences that are highly-similar (PUB-HS) to these PUB-I TCR-sequences. We found that almost one third of all TCR nucleotide-sequences represented PUB-I TCR amino-acid (AA) sequences and found an additional 12% of PUB-HS TCRs differing by maximally 3 AAs. We illustrate that these PUB-I and PUB-HS TCRs were structurally related and contained shared core-sequences in their TCR-sequences. We found a prevalence of PUB-I and PUB-HS TCRs of up to 50% among individuals and showed frequencies of virus-specific PUB-I and PUB-HS TCRs making up more than 10% of each virus-specific T-cell population. These findings were confirmed by using an independent TCR-database of virus-specific TCRs. We therefore conclude that the magnitude of the contribution of PUB-I and PUB-HS TCRs to these virus-specific T-cell responses is high. Because the T cells from these virus-specific memory TCR-repertoires were the result of successful control of the virus in these healthy individuals, these PUB-HS TCRs and PUB-I TCRs may be attractive candidates for immunotherapy in immunocompromised patients that lack virus-specific T cells to control viral reactivation. Show less
In this thesis I have firstly applied gene transfer technologies to the redirection of T cell specificity, by trying to overcome limitations related to non-viral gene transfer systems. In the... Show moreIn this thesis I have firstly applied gene transfer technologies to the redirection of T cell specificity, by trying to overcome limitations related to non-viral gene transfer systems. In the second part of my PhD work, I focused on genetic screens, which, I applied to understanding molecular mechanisms of escape from T cell attack and to reveal mechanisms of PD-L1 regulation. The work presented in this thesis may on the one hand facilitate the clinical application of non-viral-based gene transfer systems in T cells. On the other hand, the more fundamental discoveries related to IFN-γ-mediated tumor cell killing and PD-L1 regulation may help to further understand resistance toward immunotherapies and how to overcome them. Show less
Cancer immunotherapy has taken up its place in oncological practice and it is likely there to stay. Although the field has come from far, much is still to learn as oncologists observe that not... Show moreCancer immunotherapy has taken up its place in oncological practice and it is likely there to stay. Although the field has come from far, much is still to learn as oncologists observe that not all patients with the same disease type respond to cancer immunotherapy, Furthermore, in some cancer types, no clinical benefit is observed at all, despite the presence of an abundant local immune infiltrate, indicating that our understanding of cancer – immune interaction is still incomplete. The overall goal of this thesis is to help address these matters in three ways. First, we have retrospectively analyzed a cohort of melanoma patients treated with ipilimumab, an anti-CTLA-4 antibody, for markers of responsiveness and review the literature to explore the limitations and curative potential of treatment strategies currently used in the clinic or under development. Second, we have developed several technology platforms that allow us to characterize and compare different types of T-cell responses that are directed against tumor-specific antigens in patient tumor material. Third, we aim to increase our understanding of the potential of cancer immunotherapy in ovarian and colorectal cancer, by analysis of the tumor-reactive compartment within these diseases. Show less
Uchtenhagen, H.; Abualrous, E.T.; Stahl, E.; Allerbring, E.B.; Sluijter, M.; Zacharias, M.; ... ; Achour, A. 2013
The minor histocompatibility (mH) antigen HA-1 is expressed by cells of hematopoietic origin only. The sequences of the immunogenic CTL epitope VLHDDLLEA (HA-1H) and the VLRDDLLEA (HA-1R)... Show moreThe minor histocompatibility (mH) antigen HA-1 is expressed by cells of hematopoietic origin only. The sequences of the immunogenic CTL epitope VLHDDLLEA (HA-1H) and the VLRDDLLEA (HA-1R) counterpart differ by one aminoacid. Selectively infusing HA-1H specific donor cytotoxic T cells may mediate a strong GvL effect with a low risk for GvHD. However, this HA-1H specific immunotherapy is currently feasible only for HLA-A2 HA-1HH or HA-1HR patients who relapsed following an SCT from an HLA-A2 HA-1RR donor. In addition, the therapy is not guaranteed for all of these patients. For instance, the anonymous umbilical cord blood (UCB) donors cannot be traced again for use of DLI or adoptive immunotherapy following transplantation. Moreover, the success rate of HA-1H specific HLA2 restricted CTL induction is donor dependent. This thesis describes the following important features, which may lead to extension of the patient population that may benefit from HA-1 specific immunotherapy: - The instable natural presentation of HA-1R in HLA-A2. - A novel HLA-B60 restricted HA-1H epitope. - Hematopoietic-specific CTLs from UCB directed against HA-1H in the context of HLA-A2. - HA-1 specific TCR transfer directing non- HA-1 TCR expressing adult and UCB CD8+ T cells to hematopoietic-specific cytolytic activity. Show less
