ALBERT

Description: Graft-versus-host disease (GVHD) represents the major nonrelapse complication of allogeneic hematopoietic cell transplantation. Although rare, the CNS and the eye can be affected. In this study, manifestation in the retina as part of the CNS and T-cell epitopes recognized by the allogeneic T cells were evaluated. In 2 of 6 patients with posttransplantation retina diseases and 6 of 22 patients without ocular symptoms, antigen-specific T-cell responses against retina-specific epitopes were observed. No genetic differences between donor and recipient could be identified indicating T-cell activation against self-antigens (graft versus self). Transplantation of a preexisting immunity and cross-reactivity with ubiquitous epitopes was excluded in family donors and healthy individuals. In summary, an immunological reaction against retina cells represents a mechanism of graft-versus-host interaction following hematopoietic cell transplantation.

Description: Introduction: Neurological symptoms after allogeneic hematopoietic cell transplantation (HCT) represent diagnostic challenges, since their onset can be rapid and permanent neurological damage is imminent. Little data is available on incidence, morbidity and mortality of central nervous system (CNS) complications after allogeneic HCT. Methods: We retrospectively analyzed data from 1204 patients undergoing allogeneic HCT at our center within the last 10 years. Out of this cohort, 102 patients (8.6%; 38 women and 64 men, median age 55 years, range 19-75 years) suffered from 107 post-HCT CNS complications. Underlying diagnoses were acute (ALL n=24; AML n=49) or chronic leukemia (CLL n=2; CML n=1; CMML n=2), myelodysplastic (n=8) or myeloproliferative (n=5) syndromes, non-Hodgkin lymphoma (n=10) or severe aplastic anemia (n=1). Conditioning was performed using reduced-intensity (n=61) or myeloablative (n=41) regimens. Grafts were applied from matched related (n=22), mismatched related (n=1), haploidentical (n=4), matched unrelated (n=49) or mismatched unrelated donors (n=26). 41 patients in the cohort suffered from acute (median grade 1; grades 1-4) and 41 patients from chronic GvHD (limited n=20; extensive n=21), respectively. Results: CNS complications comprised cerebrovascular events (hemorrhagic, n=26; thromboembolic, n=10), infections (n=19; viral infections including CMV and VZV n=11; bacterial n=2; toxoplasmosis n=6), toxic leukoencephalopathy (n=11), inflammatory changes without detection of underlying cause (n=14) including cerebral vasculitis or cerebral graft versus host disease (GvHD), disease relapse (n=13; meningeosis leucaemica n=10; myeloid sarcoma of the dura n=1), secondary intracerebral tumors (n=2), posterior reversible encephalopathy syndrome (PRES; n=4), seizures (n=6), migraine (n=1), or neurological and psychiatric syndromes without detection of a defined etiology (n=2). Median time between HCT and onset of CNS symptoms was 4.6 months (range, 0-155 months). CNS complications occurring early after HCT comprised hemorrhagic events (median 1.4 months after HCT; 0.2-107.9 months), seizures (median 3.0 months after HCT; 0.1-6.9 months), infections (median 4.7 months after HCT; 0.1-70.3 months), leukoencephalopathy (median 3.7 months; 0-33.6 months) and psychiatric disorders (median 1.3 months; 0.8-6.4 months). Other complications occurred later (p=0.006) comprising inflammatory disorders without a definite cause (median 7.1 months; 1.2-97.4 months), ischemia (median 29.9 months; 0.6-95.5 months), and malignant causes (median 10 months; 1.7-156 months). Treatment was guided by the respective diagnosis and symptoms including transfusion of platelet concentrates, interventional recanalization, antibiotics or virostatic drugs, immunosuppression, or systemic and/or intrathecal chemotherapy. These therapies led to complete resolution of neurological symptoms in 31 (30%) patients. In 43 patients (42%) amelioration with residual symptoms (n=15; 15%) or stabilization (n=28; 27%) was achieved. In 28 cases (27%) no response to therapy was observed resulting in a letal outcome (causes of death: cerebrovascular events n=7 (19%); infections n=10 (53%); leukencephalopathy n=2 (18% ); GvHD n=1 (7% l); CNS malignancy n=6 (40% ); unknown cause n=2). Risk factors for the development of CNS complications were thrombocytopenia (bleeding, n=18), positivity for toxoplasmosis before HCT (toxoplasma infections, n=6), arterial hypertension (PRES, n=4) and possibly irradiation of the neurocranium (inflammatory diseases; n=4). Median overall survival was 13.8 and 6.4 months after HCT and onset of CNS complications, respectively. Cumulative incidence of CNS disease related deaths was 11% and 21% at 100 days and 12 months, respectively (1% and 2% for the complete patient cohort of 1,204 patients). Conclusions: Complications and/or manifestations in the CNS account for a significant number of HCT-related complications resulting in significant mortality and morbidity. 70% of these patients will suffer from irreversible neurological damage. Therefore, precise and timely diagnosis is necessary to guide causal therapy and prevent permanent damage. Disclosures No relevant conflicts of interest to declare.

Description: Graft versus Host Disease (GvHD) is the major complication of allogeneic hematopoetic cell transplantation (HCT). It mostly affects the gastrointestinal tract, skin or liver, but may also involve the central nervous system (CNS). Although GvHD is believed to be mainly mediated by T cells recognizing HLA mismatches or minor histocompatibility antigens (MHC-restricted peptides differing in single amino acids based on protein sequence variants between donor and recipient due to genetic differences), limited evidence is known about the exact MHC-restricted T cell epitopes recognized on recipient cells. In this study, we evaluated the clinical manifestation of GvHD in the posterior eye segment (PS) as part of the CNS and characterized self-antigens mediating reactivity of allogeneic T cells. The first patient group comprised 6 individuals (3 women and 3 men, median age 40 years, range 20-58 years) with diseases of the PS after HCT. Diseases were ALL (n=4), AML (n=1) and MPS (n=1). 8 transplantations (1-2 per patient) were performed using grafts from matched related (MRD, n=1), matched unrelated (MUD, n=4), mismatched unrelated (MMUD, n=2) or haploidentical (n=1) donors. The second group included 22 patients (7 women and 15 men, median age 55 years, range 29-69 years) irrespective of ocular symptoms recruited before HCT. Diseases were AML (n=7), CML (n=1), MDS (n=4), MPS (n=5), multiple myeloma (n=1) and lymphoma (n=4). All patients received grafts from HLA-identical donors (MRD n=7, MUD n=15). GvHD prophylaxis was performed using standard protocols. Peripheral blood mononuclear cells (PBMC) and DNA were isolated from blood samples. Autologous cell samples were blood samples before or oral mucosa after HCT. Allogeneic cells were obtained from patients with complete donor chimerism. DNA sequencing was performed to identify donor-recipient single nucleotide polymorphisms (SNP). Retina specific candidate epitopes derived from the retinal guanylate cyclase 2D (GUCY2D), the retinoid binding protein (RBP) and the guanylate cyclase activating proteins A1 und B1 (GUCA1A/GUCA1B) were predicted based on known SNP and individual protein sequences using the database EpiToolKit. PBMC were prestimulated with both wildtype and SNP peptides. T cell reactivity was determined in ELISpot and intracellular cytokine staining. Moreover, T cells from 5 family donors were evaluated. All epitopes were evaluated in at least 8 healthy individuals carrying the respective HLA-subtype. Immunogenicity of MHC-I restricted candidate epitopes was determined in in vitro priming. PS diagnoses were optical atrophy (n=2), in 1 case combined with a selective dysfunction of the cones, optic neuritis (n=2), anemic retinopathy (n=1) and VZV retinitis (n=1). In two of these patients (one with selective cone dystrophy, the other with VZV retinitis) antigen specific T cells against MHC-II restricted GUCY2D epitopes could be detected 24 and 40 months after HCT. DNA sequencing did not reveal a SNP indicating recognition of self-antigens. In 6/22 patients without PS symptoms, retina-specific T cells could be detected, here directed against MHC-II restricted epitopes derived from GUCA1A (n=3), GUCA1B (n=3) and GUCY2D (n=3) between 4 and 14 months after HCT. After stimulation with the variant peptide, no T cell reactivity occurred, confirming that the observed responses were sequence specific. T cell responses tended to increase over time but could disappear at certain time points. Again, no SNP could be observed. Hence, T cell reactivity was directed against self-epitopes. Transplantation of retina-antigen specific cells and cross-reactivity against naturally occurring epitopes were excluded since no reactivity could be detected in donor samples and healthy individuals. In in vitro priming experiments, 36/55 of MHC-I restricted peptides could be confirmed as T cell epitopes. Thus, GvHD manifestations of the retina can be detected in patients after allogeneic HCT and can be mediated by antigen-specific T cells. Development of PS GvHD may be triggered by viral infections and should be considered in case of atypical ophthalmologic findings. The antigens recognized hereby can be self-antigens and do not need to be based on genetic differences between donor and recipient. In summary, recognition of self-antigens by allogeneic T cells represents a novel pathomechanism of graft-host-interaction in patients undergoing allogeneic HCT. Disclosures No relevant conflicts of interest to declare.

Description: Key Points MYD88 mutation analysis significantly improves the detection rate of vitreoretinal B-cell lymphoma. The high frequency of MYD88 mutations in primary VRL provides further evidence that VRL and primary CNS lymphoma represent the same entity.