Intrahepatic myeloid-cell aggregates enable local proliferation of CD8+ T cells and successful immunotherapy against chronic viral liver infection

Abstract Abstract 1321 Following T cell depleted (TCD) allogeneic stem cell transplantation (alloSCT) more patients (pts) show mixed chimerism (MC) as compared to non-TCD transplantation. MC is frequently measured in bone marrow (BM) leukocytes and it is thought to reflect the persistence of recipient hematopoietic stem cells including the malignant hematopoietic cell lineages. MC is associated with increased relapse rate, for which pre-emptive donor lymphocyte infusion can be administered. Most pts are transplanted for myeloid or B cell derived hematological malignancies, and it is unclear whether MC in BM leukocytes truly reflects the persistence of recipient cells in these B or myeloid cell lineages, since the total leukocyte fraction is a composite measurement of chimerism status in different hematopoietic cell lineages. Since T cell neogenesis is almost absent in the first 6 months after alloSCT, T cell chimerism probably reflects survival and expansion of residual recipient and/or donor T cells. Therefore we hypothesize that leukocyte MC may be strongly influenced by T cell chimerism. Furthermore, increasing leukocyte MC has been thought to be associated with expansion of the potentially malignant compartment. However, we hypothesize that increasing leukocyte MC will be influenced by factors controlling T cell chimerism. In this study we investigated whether overall leukocyte chimerism after TCD alloSCT corresponds with leukemia lineage specific (B cell or myeloid) chimerism and whether T cell chimerism was influenced by immunological factors such as the conditioning regimen, antigenic stimulation during viral infection or graft versus host disease (GvHD), complicating the interpretation of leukocyte MC. Detailed lineage specific chimerism analysis was performed in 49 pts receiving a TCD alloSCT after a myeloablative (MA) (n=24) or non myeloablative (NMA) conditioning regimen (n=25) for hematological malignancies. Pts with relapses within the first year after alloSCT were excluded. At 3 months after alloSCT PB was collected, and B cells, monocytes and granulocytes (myeloid cells), CD4+ and CD8+ T cells were sorted. Red blood cell lysis was performed to obtain the unseparated leukocyte fraction. Subsequently, DNA was isolated to perform chimerism analysis using short tandem repeats - PCR. In 71% of the pts analyzed MC was detected in the T cell compartment, with a median percentage of 25.3% (range 1–100), whereas only 21% of the pts were MC in the B and myeloid cell lineages, with a median percentage of 6% (2.1-29.2). In the BM leukocyte compartment, 38% of the pts were MC with a median percentage of 4% (2-46). Of the pts with MC in the BM leukocyte compartment, 33% showed MC in the T cell compartment and complete donor chimerism in the B and myeloid compartment, demonstrating that lineage specific chimerism frequently does not correspond with leukocyte chimerism, since it is influenced by T cell chimerism. In NMA transplanted pts, a significantly higher percentage of recipient T cells (42% (0-99.5) compared to MA transplanted pts (1.6% (0-99.5) was detected. In MA transplanted pts, a higher percentage (14% (0-99.5) of recipient cells was detected if pts were transplanted with a related donor, compared to pts transplanted with an unrelated or mismatch related donor (0% (0-5.7) receiving additional alemtuzumab treatment as part of the conditioning regimen. Pts developing GvHD grade I-II before 2 months after alloSCT showed a significant lower percentage of recipient T cells at 3 months after alloSCT (1.7% (0-86.4) as compared to pts without GvHD (61.4% (7.1-99.5). To analyze the influence of pre-transplantation recipient CMV serostatus on T cell chimerism, pts transplanted with a CMV seronegative donor were selected. CMV seropositive pts showed higher percentages recipient CD8 T cells (30.5% (0-99.5) compared to CMV seronegative pts (3.1% (0-97.9), indicating the persistence of residual memory CD8 T cells after alloSCT. In conclusion, these results illustrate that BM leukocyte chimerism frequently does not correspond with B and myeloid cell chimerism, since it was strongly influenced by T cell chimerism, which was in turn influenced by the conditioning regimen and immunological events such as GvHD and CMV serostatus. Therefore, to analyze the persistence of recipient hematopoietic stem cells including the malignant hematopoietic cell lineages, lineage specific chimerism analysis should be performed. Disclosures: No relevant conflicts of interest to declare.

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A Point Mutation in the Juxtamembrane Wedge of CD45 Impacts Myeloid Development and Generates a Novel Model for Hemophagocytic Disorders in the Context of a MHC I-Restricted Transgene.

Blood ◽

10.1182/blood.v110.11.317.317 ◽

2007 ◽

Vol 110 (11) ◽

pp. 317-317 ◽

Cited By ~ 1

Author(s):

Michelle L. Hermiston ◽

Fleur R. de Graaf ◽

Art Weiss

Keyword(s):

T Cells ◽

T Cell ◽

Point Mutation ◽

Cd8 T Cells ◽

Adoptive Transfer ◽

Macrophage Activation ◽

Tyrosine Phosphatase ◽

Myeloid Cell ◽

Premature Death ◽

Regulatory Function

Abstract The receptor like-protein tyrosine phosphatase CD45 is highly expressed on all nucleated hematopoietic cells and functions by modulating the activity of Src family kinases. We previously generated mice containing a point mutation in the juxtamembrane wedge of CD45 that leads to constitutive phosphatase activity. Demonstrating the critical negative regulatory function of the wedge, the CD45E613R mutation led to a lymphoproliferative disorder, lupus-like autoimmune syndrome, and premature death at 9–12 months of age. To address the intrinsic effects of the wedge mutation on the CD8 T cell lineage, we introduced a CD8 restricted T-cell receptor (TCR) transgene, OT1, specific for the antigen ovalbumin, into CD45E613R mice. Surprisingly, 100% of the CD45E613R/OT1+ mice succumb by 6 weeks of age to a rapidly progressive disease characterized by severe cachexia, hemophagocytosis, and markedly elevated interferon gamma levels. This phenotype shares similarity to the human hemophagocytic syndromes hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS). The aims of this study are to identify the mechanistic basis and the cell type(s) responsible for this phenotype. Using a genetic approach, we demonstrate that the phenotype is maintained in CD45E613R/OT1+mice on a Rag1−/− background, thus implicating myeloid and/or CD8 T cells in disease pathogenesis. Analysis of myeloid cell development, phagocytic function, and signaling indicate that the wedge mutation operates in this lineage. Despite the intrinsic hyperresponsiveness of CD45E613R macrophages, adoptive transfer experiments demonstrate they are not essential for disease. However, adoptive transfer of purified CD45E613R/OT1+ CD8 T cells into either CD45 mutant or CD45 wildtype (wt) is sufficient to initiate disease. Interestingly, CD45E613R CD8 OT+ T cells are not dominant over CD45wt CD8+ cells. In addition we show that transfer of CD45wt CD8+ T cells into ill mice can delay disease progression. We hypothesize that, in the setting of the wedge mutation, the restricted repertoire of the CD8 T cells in CD45E613R/OT1+ mice might not be able to limit macrophage activation. We believe these mice may represent a useful model for understanding the molecular pathogenesis of hemophagocytic disorders, devastating and often fatal diseases in humans.

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Tumor microenvironment associated with increased pretreatment density of activated PD-1+ LAG-3+/− TIM-3− CD8+ T cells facilitates clinical response to axicabtagene ciloleucel (axi-cel) in patients (pts) with large B-cell lymphoma.

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.15_suppl.3022 ◽

2020 ◽

Vol 38 (15_suppl) ◽

pp. 3022-3022

Author(s):

Jerome Galon ◽

Nathalie Scholler ◽

Regis Perbost ◽

Sarah Turcan ◽

Corinne Danan ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Clinical Response ◽

Cd8 T Cells ◽

Objective Response ◽

Cell Subset ◽

Myeloid Cell ◽

B Cell Lymphoma ◽

T Cell Subsets ◽

Tumor Biopsy

3022 Background: Axi-cel is a US and EU-approved autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy for pts with relapsed/refractory large B cell lymphoma after ≥ 2 prior therapies. In ZUMA-1 (NCT02348216), the objective response rate was 83% (58% complete response rate; Locke et al. Lancet Oncol. 2019). T cell-related biology (Immunosign 21; Immunoscore) measured pretreatment in the tumor microenvironment (TME) was associated with response to axi-cel (Rossi et al. AACR 2018. #LB-016; Rossi et al. AACR 2019. #CT153). This expanded analysis characterized the pretreatment TME immune contexture and examined associations between immune cell subsets and response. Methods: In ZUMA-1, pts received axi-cel at a target dose of 2.0 × 106 CAR T cells/kg. Archival pretreatment tumor biopsy samples were analyzed by multiplex immunohistochemistry (Brightplex). Two panels were developed and applied to assess T cell (CD3, CD8, FoxP3, PD-1, LAG-3, TIM-3) and myeloid cell (CD11b, CD14, CD15, LOX1, S100A9, CD68) subsets (n = 14 total). The association between T cell and myeloid cell subset density, prespecified immune scores (Immunosign 21; Immunoscore), and objective response was evaluated. T test values were based on Brightplex analysis. Results: Pretreatment tumor biopsy samples from 18 pts were analyzed (14 objective responders and 4 nonresponders). The pretreatment TME comprised all major myeloid and T cell subsets, with diverse distribution across samples analyzed. The median TME density of monocytes (CD11b+ CD15− CD14+; 1215 cells/mm2) and macrophages (CD68+; 530 cells/mm2) was greater than that of the total CD8+ T cell subset (312 cells/mm2). The pretreatment Immunosign 21 and Immunoscore scores associated positively with the density of all major T cell subsets and some myeloid subsets. The density of activated CD8+ T cells (PD-1+ LAG-3+/− TIM-3−) was most significantly associated with clinical response versus other T cell subsets. The density of nonactivated CD8+ T cells (PD-1− LAG-3− TIM-3−) and exhausted CD8+ T cells (PD-1+ LAG-3+ TIM-3+) were not significantly associated with response. Additional characterization of the immune contexture and correlative analysis of cell subsets will be presented. Conclusions: These results suggest that a TME associated with increased density of activated PD-1+ LAG-3+/− TIM-3− CD8+ T cells, measurable pretreatment, facilitates clinical response in pts post–axi-cel.

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