Phosphorylated STAT3 expression in hematopoietic stem cell transplant-associated large granular lymphocytic leukemia

Persistent Large Granular Lymphocyte Clonal Expansions: “The Root of Many Evils”—And of Some Goodness

Simple Summary

Large granular lymphocyte leukemia (LGLL) is a chronic disorder of either mature T or NK lymphocytes. As clonal expansions of the immune system cells, difficulties in the distinction between a true neoplasia and a physiological reactive process have been common since its description. We review here the different conditions associated with persistent clonal LGL expansions and discuss their potential origin and whether they can modulate the clinical features.

Abstract

Large granular lymphocyte leukemia (LGLL) is a chronic disease of either mature phenotype cytotoxic CD3+ T lymphocytes or CD3- NK cells. LGLL diagnosis is hampered by the fact that reactive persistent clonal LGL expansions may fulfill the current criteria for LGLL diagnoses. In addition to the presence of characteristic clinical and hematological signs such as anemia or neutropenia, LGLL/LGL clonal expansions have been associated with an array of conditions/disorders. We review here the presence of these persistent clonal expansions in autoimmune, hematological disorders and solid neoplasms and after hematopoietic stem cell transplantation. These associations are a unique translational research framework to discern whether these persistently expanded LGL clones are causes or consequences of the concomitant clinical settings and, more importantly, when they should be targeted.

Florid Pulmonary Mycobacterium avium-intracellulare Infection in a Patient With Large Granular Lymphocytic (LGL) Leukemia on Chronic Cyclophosphamide

Large granular lymphocytic (LGL) leukemia is a rare form of incurable chronic leukemia frequently complicated by life-threatening cytopenias. The less common NK-cell variant of this disorder poses a diagnostic challenge and its etiologic basis is poorly understood. Here we present the case of an elderly man diagnosed with LGL leukemia after presenting with severe Coombs-negative hemolytic anemia, who had a robust durable response to oral cyclophosphamide. Close to two years after initial diagnosis, he developed a florid Mycobacterium avium-intracellulare (MAI) infection of the lungs. We discuss the clinical and pathologic features of this case, highlighting aspects common to this disorder and areas of clinical uncertainty. We hope to both raise awareness of the risk for pulmonary MAI infection in patients treated with lymphodepleting drugs and to motivate the prospective evaluation of strategies to prevent opportunistic infections in LGL leukemia.

Large Granular Lymphocytosis With Cytopenias After Allogeneic Blood or Marrow Transplantation: Clinical Characteristics and Response to Immunosuppressive Therapy

Large granular lymphocytosis (LGL)-or LGL leukemia-is a T- or NK-cell lymphoproliferative disorder that often results in cytopenias and autoimmune phenomena. Several studies have described LGL in a subset of patients after allogeneic blood or marrow transplantation (alloBMT), almost exclusively in the setting of asymptomatic lymphocytosis. Some have suggested an association with improved transplant-related outcomes. In contrast, clinically significant LGL after alloBMT is only described in small case reports. This study sought to assess the characteristics, significance, and response to treatment of LGL associated with unexplained anemia, thrombocytopenia, or neutropenia after alloBMT. We performed a retrospective analysis of 150 patients who were evaluated for LGL by peripheral blood flow cytometry (LGL flow) for unexplained cytopenias following initial engraftment after alloBMT from January 1 2012 to July 1, 2019. We identified patients with abnormally increased populations of LGL cells (LGL+) as assessed by Johns Hopkins Hematopathology. We collected demographic, transplantation, and LGL treatment information from electronic medical records. We compared LGL+ patients to patients with unexplained cytopenias with negative flow cytometry for LGL (LGL-) in this cohort. We also assessed change in blood counts after 4 weeks of immunosuppressive therapy in LGL+ patients. Cytopenias occurred at a median of 5.7 months (range 1-81) after alloBMT. The majority of the transplants were nonmyeloablative from haploidentical donors, and all patients received post-transplantation cyclophosphamide for graft-versus-host disease prophylaxis, consistent with the overall alloBMT characteristics at our center. We identified 70 patients with LGL and cytopenias, representing 47% of those evaluated by flow cytometry. There were no significant demographic or transplant-related differences between LGL+ patients and LGL- patients. The median age was 59, and 63% were male. LGL+ patients were more likely to have had cytomegalovirus (CMV) viremia (73% versus 28%, P < .0001), but not acute or chronic graft-versus-host disease. LGL+ patients had higher absolute lymphocyte counts (1500 versus 485/ mm³, P < .0001), a trend toward lower absolute neutrophil count (660 versus 965/mm³, P = .17), and lower neutrophil to lymphocyte ratio (0.39 versus 1.71, P < .001). There were no differences in overall survival or relapse-free survival. Of those with T-cell LGL, 45 were assessed for T-cell receptor clonality. In all, 22% were clonal, 53% oligoclonal, 4% polyclonal, and 20% indeterminate. Thirty (43%) LGL+ patients received immunosuppressive therapy (IST) for cytopenias. First-line treatment was corticosteroids for 25 (83%). Among those treated, there was an increase in median absolute neutrophil count from 720 before treatment to 1990/mm³ after 4 weeks (P = .0017). Thrombocytopenia and anemia showed at most a mild improvement with IST. LGL was a common association with otherwise unexplained cytopenias after alloBMT, almost always after prior CMV infection. LGL in the setting of cytopenias did not predict improved transplantation outcomes compared to those with cytopenias without presence of LGL. IST was effective at improving neutropenia associated with LGL after alloBMT.

Intra-hydrogel culture prevents transformation of mesenchymal stem cells induced by monolayer expansion

In this study, we report that the intra-hydrogel culture system mitigates the transformation of mesenchymal stem cells (MSCs) induced by two-dimensional (2D) expansion. MSCs expanded in monolayer culture prior to encapsulation in collagen hydrogels (group eMSCs-CH) featured impaired stemness in chondrogenesis, comparing with the freshly isolated bone marrow mononuclear cells seeded directly in collagen hydrogels (group fMSCs-CH). The molecular mechanism of the in vitro expansion-triggered damage to MSCs was detected through genome-wide microarray analysis. Results indicated that pathways such as proteoglycans in cancer and pathways in cancer expansion were highly enriched in eMSCs-CH. And multiple up-regulated oncoma-associated genes were verified in eMSCs-CH compared with fMSCs-CH, indicating that expansion in vitro triggered cellular transformation was associated with signaling pathways related to tumorigenicity. Besides, focal adhesion (FA) and mitogen-activated protein kinase (MAPK) signaling pathways were also involved in in vitro expansion, indicating restructuring of the cell architecture. Thus, monolayer expansion in vitro may contribute to vulnerability of MSCs through the regulation of FA and MAPK. This study indicates that intra-hydrogel culture can mitigate the monolayer expansion induced transformation of MSCs and maintain the uniformity of the stem cells, which is a viable in vitro culture system for stem cell therapy.

Large granular lymphocytosis after transplantation

Post-transplant lymphoproliferative disorders (PTLD) represent a heterogeneous group of diseases that occur following transplantation. Large granular lymphocytic (LGL) lymphocytosis is one type of PTLD, ranging from reactive polyclonal self-limited expansion to oligo/monoclonal lymphocytosis or even to overt leukaemia. LGL lymphocytosis in transplant recipients may present as a relatively indolent version of the condition and may be more common than reported, but its natural history and clinical course have not been well described, and the lack of a reliable classification system has limited studies on this disease. Patients with unexplained cytopenias, autoimmune manifestations, or unexpected remissions may be mislabelled. The purpose of this review was to evaluate the clinical features, immunophenotypes, etiopathogenesis, diagnosis, outcomes and treatment of post-transplantation LGL lymphocytosis. In conclusion, LGL lymphocytosis is a frequent occurrence after transplantation that correlates with certain procedural variables and post-transplant events. LGL lymphocytosis should be considered in patients with unexplained lymphocytosis or when pancytopenia develops after transplantation. The diagnosis of LGL lymphocytosis requires a demonstration of monoclonality, but clonality does not indicate malignancy. Additional studies are necessary to further delineate the potential effects of large granular lymphocytes in the long-term prognosis of post-transplant patients.