Autoimmunity and B-cell dysfunction in chronic proliferative disorders of large granular lymphocytes/natural killer cells

Neutropenia and Large Granular Lymphocyte Leukemia: From Pathogenesis to Therapeutic Options

Large granular lymphocyte leukemia (LGLL) is a rare lymphoproliferative disorder characterized by the clonal expansion of cytotoxic T-LGL or NK cells. Chronic isolated neutropenia represents the clinical hallmark of the disease, being present in up to 80% of cases. New advances were made in the biological characterization of neutropenia in these patients, in particular STAT3 mutations and a discrete immunophenotype are now recognized as relevant features. Nevertheless, the etiology of LGLL-related neutropenia is not completely elucidated and several mechanisms, including humoral abnormalities, bone marrow infiltration/substitution and cell-mediated cytotoxicity might cooperate to its pathogenesis. As a consequence of the multifactorial nature of LGLL-related neutropenia, a targeted therapeutic approach for neutropenic patients has not been developed yet; moreover, specific guidelines based on prospective trials are still lacking, thus making the treatment of this disorder a complex and challenging task. Immunosuppressive therapy represents the current, although poorly effective, therapeutic strategy. The recent identification of a STAT3-mediated miR-146b down-regulation in neutropenic T-LGLL patients emphasized the pathogenetic role of STAT3 activation in neutropenia development. Accordingly, JAK/STAT3 axis inhibition and miR-146b restoration might represent tempting strategies and should be prospectively evaluated for the treatment of neutropenic LGLL patients.

Myasthenia Gravis and Large Granular Lymphocytic Leukemia: a rare association

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disorder sometimes observed in hematologic malignancies as a paraneoplastic syndrome. T-cell Large Granular Lymphocytic Leukemia (T-LGLL) is a rare lymphoproliferative clonal frequently associated with autoimmune disorders. Here we report two patients with T-LGLL who developed MG. In both patients the MG was bulbar without generalized weakness and did not involve the thymus. The treatment of T-LGLL led to the resolution of MG symptoms and decrease in acetylcholine receptor antibody titers in both patients suggesting a causative association.

Dysfunction of immune system in the development of large granular lymphocyte leukemia

OBJECTIVES

Large granular lymphocyte (LGL) leukemia is a rare type of lymphoproliferative disease caused by clonal antigenic stimulation of T cells and natural killer (NK) cells.

METHODS

In this review, we focus on the current knowledge of the immunological dysfunctions associated with LGL leukemia and the associated disorders coexistent with this disease. Novel therapeutic options targeting known molecular mechanisms are also discussed.

RESULTS AND DISCUSSION

The pathogenesis of LGL leukemia involves the accumulation of gene mutations, dysregulated signaling pathways and immunological dysfunction. Mounting evidence indicated that dysregulated survival signaling pathways may be responsible for the immunological dysfunction in LGL leukemia including decreased numbers of neutrophils, dysregulated signal transduction of NK cells, abnormal B-cells, aberrant CD8+ T cells, as well as autoimmune and hematological abnormalities.

CONCLUSION

A better understanding of the immune dysregulation triggered by LGL leukemia will be beneficial to explore the pathogenesis and potential therapeutic targets for this disease.

Rational management approach to pure red cell aplasia

Pure red cell aplasia is an orphan disease, and as such lacks rationally established standard therapies. Most cases are idiopathic; a subset is antibody-mediated. There is overlap between idiopathic cases and those with T-cell large granular lymphocytic leukemia, hypogammaglobulinemia, and low-grade lymphomas. In each of the aforementioned, the pathogenetic mechanisms may involve autoreactive cytotoxic responses. We selected 62 uniformly diagnosed pure red cell aplasia patients and analyzed their pathophysiologic features and responsiveness to rationally applied first-line and salvage therapies in order to propose diagnostic and therapeutic algorithms that may be helpful in guiding the management of prospective patients, 52% of whom were idiopathic, while the others involved large granular lymphocytic leukemia, thymoma, and B-cell dyscrasia. T-cell-mediated responses ranged between a continuum from polyclonal to monoclonal (as seen in large granular lymphocytic leukemia). During a median observation period of 40 months, patients received a median of two different therapies to achieve remission. Frequently used therapy included calcineurin-inhibitors with a steroid taper yielding a first-line overall response rate of 76% (53/70). Oral cyclophosphamide showed activity, albeit lower than that produced by cyclosporine. Intravenous immunoglobulins were effective both in parvovirus patients and in hypogammaglobulinemia cases. In salvage settings, alemtuzumab is active, particularly in large granular lymphocytic leukemia-associated cases. Other potentially useful salvage options include rituximab, anti-thymocyte globulin and bortezomib. The workup of acquired pure red cell aplasia should include investigations of common pathological associations. Most effective therapies are directed against T-cell-mediated immunity, and therapeutic choices need to account for associated conditions that may help in choosing alternative salvage agents, such as intravenous immunoglobulin, alemtuzumab and bortezomib.

Gamma heavy chain disease associated with large granular lymphocytic leukemia: A report of two cases and review of the literature

OBJECTIVE AND IMPORTANCE

Gamma heavy chain diseases (γHCD) and large granular lymphocyte (LGL) leukemia are two rare lymphoproliferative diseases, respectively with B and T phenotype. Both γHCD and LGL leukemia share some similar clinical features, such as cytopenias, splenomegaly, and recurrent infections. Association of these two diseases is exceptional and suggest pathogenic link. We report two cases of γHCD associated with T-LGL leukemia.

CLINICAL PRESENTATION

Patient 1 was a 70-year-old woman, with lymphoplasmacytic lymphoma, refractory to chlorambucil-rituximab treatment. She developed during the follow up a γHCD with T-LGL leukemia, unresponsive to melphalan, thalidomide, and steroids, requiring supportive care. Patient 2 was a 40-year-old man with chronic severe asymptomatic neutropenia, revealing both γHCD and T-LGL leukemia. He is still well without any treatment nor complications, with 7 years follow up.

CONCLUSION

Several types of B lymphoproliferative disease are associated with LGL leukemia. Although exceptional, this association of two rare lymphoproliferative disorders, with a different phenotype, does not seem fortuitous.

Large granular lymphocytic leukemia presenting late after solid organ transplantation: a case series of four patients and review of the literature

Post-transplantation lymphoproliferative disorder (PTLD) is a significant complication of solid organ transplantation. Most PTLD is of the B-cell subtype, although T-cell subtype PTLD uncommonly occurs. T-cell PTLDs are usually aggressive neoplasms and shorten patient and allograft survivals significantly. We present a single-center case series of 4 patients who developed T-cell large granular lymphocytic (LGL) leukemia, a rare T-cell PTLD characterized by large granular lymphocytes that have characteristic azurophilic granules and a highly variable clinical course.

Natural killer cell lymphoproliferative disease associated with combined peripheral and autonomic neuropathy

Natural killer cell proliferation is an uncommon haematological disorder that has a number of different clinical manifestations. There have been only two prior reports linking this process with neurological disease, both reports describing peripheral neuropathy. We report the case of a young man presenting with a short history of lethargy, lower limb paraesthesia and marked weight loss who was found to have a natural killer cell lymphocytosis and features of both an autonomic and a peripheral neuropathy. The patient's clinical features responsed to a combination of cytotoxic and immunosuppressive therapy, and the patient is now clinically stable with mild ongoing lymphocytosis, diarrhoea and postural hypotension. We review the possible pathological link between natural killer cells and neurological disease.

Scleritis and multiple systemic autoimmune manifestations in chronic natural killer cell lymphocytosis associated with elevated TCRalpha/beta+CD3+CD4-CD8- double-negative T cells

BACKGROUND/AIMS

Chronic natural killer lymphocytosis (CNKL) has been associated with systemic autoimmunity; however, its association with scleritis or ocular autoimmunity has not been characterised. The natural killer (NK) cell function and immunophenotype of a patient with CNKL who developed bilateral scleritis and multiple systemic autoimmune findings were evaluated.

METHODS

The ophthalmic records of a patient with CNKL and scleritis were reviewed over a 6-year period. Flow cytometry was performed to evaluate T cell, NK and B cell populations. NK cellular functions (ie, NK cytotoxicity and cytokine/chemokine production following interleukin 2 (IL2) stimulation) were evaluated.

RESULTS

A 56-year-old woman with vitiligo, psoriatic arthritis, thyroiditis, erythema nodosum, bilateral anterior scleritis and Sjogren syndrome was managed with multiple immunosuppressive medications, including prednisone, mycophenolate mofetil and methotrexate. Flow cytometry showed a persistent elevation of CD56(+)CD3(-) NK cells greater than 40%, which was consistent with CNKL. NK cell cytotoxicity assay identified a deficiency of K562 cell lysis in the patient (1.46 mean-fold greater in control vs patient). NK cytokine/chemokine production following IL2 stimulation was also deficient (2.5-32.5-fold greater in control). Cytokines/chemokines assessed included pro-inflammatory (interferon gamma, tumor necrosis factor alpha, IL1, monocyte chemotactic protein 1) and immunoregulatory cytokines (IL4, IL5 and IL10). An abnormal elevation of TCRalpha/beta(+) CD3(+)CD4(-)CD8(-) T cells suggestive of autoimmune lymphoproliferative syndrome was observed; however, apoptosis dysfunction was not found.

CONCLUSION

The association of increased but dysfunctional NK cells in the context of multiple systemic and ocular manifestations suggests a role of NK cells in the pathogenesis of our patient's disease. Further studies regarding NK cell dysfunction and ocular autoimmunity are needed.

A critical role for DAP10 and DAP12 in CD8+ T cell-mediated tissue damage in large granular lymphocyte leukemia

Large granular lymphocyte (LGL) leukemia, or LGLL, is characterized by increased numbers of circulating clonal LGL cells in association with neutropenia, anemia, rheumatoid arthritis, and pulmonary artery hypertension (PAH). Emerging evidence suggests that LGLL cells with a CD8(+)CD28(null) phenotype induce these clinical manifestations through direct destruction of normal tissue. Compared with CD8(+)CD28(null) T cells from healthy controls, CD8(+)CD28(null) T cells from LGLL patients have acquired the ability to directly lyse pulmonary artery endothelial cells and human synovial cells. Here, we show that LGLL cells from patients possess enhanced cytotoxic characteristics and express elevated levels of activating natural killer receptors as well as their signaling partners, DAP10 and DAP12. Moreover, downstream targets of DAP10 and DAP12 are constitutively activated in LGLL cells, and expression of dominant-negative DAP10 and DAP12 dramatically reduces their lytic capacity. These are the first results to show that activating NKR-ligand interactions play a critical role in initiating the DAP10 and DAP12 signaling events that lead to enhanced lytic potential of LGLL cells. Results shown suggest that inhibitors of DAP10 and DAP12 or other proteins involved in this signaling pathway will be attractive therapeutic targets for the treatment of LGLL and other autoimmune diseases and syndromes.

Cold antibody autoimmune hemolytic anemias

The cold antibody autoimmune hemolytic anemias (AIHAs) are primarily comprised of cold agglutinin syndrome (CAS) and paroxysmal cold hemoglobinuria (PCH) but, in addition, there are unusual instances in which patients satisfy the serologic criteria of both warm antibody AIHA and CAS ("mixed AIHA"). CAS characteristically occurs in middle-aged or elderly persons, often with signs and symptoms exacerbated by cold. The responsible antibody is of the IgM immunoglobulin class, is maximally reactive in the cold but with reactivity up to at least 30 degrees C. Therapy is often ineffective, but newer agents such as rituximab have been beneficial in some patients. PCH occurs primarily in children, often after an upper respiratory infection. The causative antibody is of the IgG immunoglobulin class and is a biphasic hemolysin that is demonstrated by incubation in the cold followed by incubation at 37 degrees C in the presence of complement. Acute attacks are frequently severe but the illness characteristically resolves spontaneously within a few days to several weeks after onset and rarely recurs. Treatment consists of supportive care, with transfusions frequently being needed.

Diseases of large granular lymphocytes

BACKGROUND

Clonal diseases of large granular lymphocytes (LGLs) are rare lymphoproliferative malignancies that arise from either mature T-cell (CD3+) or natural killer (NK)-cell (CD3-) lineages. They manifest a distinct biologic behavior that ranges from indolent to very aggressive.

METHODS

We discuss four distinct diseases involving LGLs: indolent T-cell LGL leukemia, aggressive T-cell LGL leukemia, chronic NK-cell leukemia, and aggressive NK-cell leukemia. Furthermore, we present an up-to-date systematic review of therapies for each entity.

RESULTS

Sustained LGLs, characteristic immunophenotype, clonal origin of leukemic cells, and clinical presentation are the most important features that distinguish indolent from aggressive subtypes of LGL leukemia and guide the selection of therapy. Patients with symptomatic indolent T-cell or NK-cell LGL leukemia are usually treated with immunosuppressive therapies in contrast to aggressive T-cell and NK-cell LGL leukemia, which require intensive chemotherapy induction regimens. Novel targeted therapies using monoclonal antibodies against receptors, including CD2, CD52, the beta subunit of the interleukin-2 receptor, and small molecules such as tipifarnib, are undergoing evaluation in clinical trials.

CONCLUSIONS

Future scientific advances focusing on the delineation of molecular pathogenic mechanisms and the development of new targeted therapies for each distinct LGL leukemia entity should lead to improved outcomes of patients with these disorders.

Hairy cell leukemia: an elusive but treatable disease

Hairy cell leukemia (HCL) is a unique chronic lymphoproliferative disorder that can mimic or coexist with other clonal hematologic disorders and has been associated with autoimmune disorders. It should be entertained as an alternative diagnosis in patients with cytopenias being assigned the diagnosis of aplastic anemia, hypoplastic myelodysplastic syndrome, atypical chronic lymphocytic leukemia, B-prolymphocytic leukemia, or idiopathic myelofibrosis. Causative etiology or molecular defects remain unclear, although nonspecific chromosomal and molecular changes have been described. The typical presentation is that of a middle-aged man with an incidental finding of pancytopenia, splenomegaly, and inaspirable bone marrow. Treatment with a purine analogue, cladribine or pentostatin, results in extremely high, durable, overall, and complete response rates, although resistance and relapses do occur. A variant subtype exists and is frequently associated with a poor response. Because of its simplified dosing schedule, cladribine is commonly used as the initial therapy. Treatment of relapsed HCL is dictated by the duration of the preceding remission. Relapsed disease after a prolonged remission can often be successfully retreated with the same initial agent. Resistance in typical HCL is treated with the alternate purine analogue. New agents, such as rituximab and BL22, are actively being evaluated and show promising results in both HCL subtypes. This article uses two patients diagnosed with aplastic anemia and recently seen in consultation at our institution as a springboard to discuss the biology, pathogenesis, clinical presentation, diagnostic evaluation, and treatment options of HCL.

A patient with paroxysmal nocturnal hemoglobinuria, T cell large granular lymphocyte clonal expansion, and monoclonal gammopathy of undetermined significance

Paroxysmal nocturnal hemoglobinuria (PNH) has been described in association separately with T cell large granular lymphocyte (LGL) clonal expansions and plasma cell dyscrasias. We describe a patient with anemia related to hemolytic PNH, with concurrent T cell LGL oligoclonal expansion and IgG lambda monoclonal gammopathy of undetermined significance. Peripheral blood flow cytometry revealed decreased expression of CD55 and CD59 on erythrocytes and decreased expression of CD55 and CD66 on neutrophils. An LGL population was present in the peripheral blood and was characterized as oligoclonal by polymerase chain reaction-based analysis of the T cell receptor gamma-chain variable region. Serum protein electrophoresis with immunofixation showed a low level IgG lambda monoclonal protein. We describe the diagnostic evaluation of this patient and provide a brief review of the reported associations among PNH, LGL clonal expansion, and monoclonal gammopathy.

Large Granular Lymphocyte Leukemia

Clonal disorders of large granular lymphocytes (LGLs) represent a spectrum of biologically distinct lymphoproliferative diseases originating either from mature T cells (CD3+) or natural killer (NK) cells (CD3-). Both subtypes, T-cell and NK-cell LGL leukemia, can manifest as indolent or aggressive disorders. The majority of patients with T-cell LGL leukemia have a clinically indolent course with a median survival time >10 years. Immunosuppressive therapy with low-dose methotrexate, cyclophosphamide, or cyclosporine A can control symptoms and cytopenias in more than 50% of patients, but this approach is not curative. Several cases of an aggressive variant (CD3+ CD56+) of T-cell LGL leukemia with a poor prognosis have also been reported. Aggressive NK-cell LGL leukemia is usually a rapidly progressive disorder associated with Epstein-Barr virus (EBV), with a higher prevalence in Asia and South America. This disease is usually refractory to conventional chemotherapy, with a median survival time of 2 months. Chronic NK-cell leukemia/lymphocytosis is a rare EBV-negative disorder with an indolent clinical course. The malignant origin of this subtype is uncertain because clonality is difficult to determine in LGLs of NK-cell origin.

Clinicobiological, immunophenotypic, and molecular characteristics of monoclonal CD56-/+dim chronic natural killer cell large granular lymphocytosis

Indolent natural killer (NK) cell lymphoproliferative disorders include a heterogeneous group of patients in whom persistent expansions of mature, typically CD56(+), NK cells in the absence of any clonal marker are present in the peripheral blood. In the present study we report on the clinical, hematological, immunophenotypic, serological, and molecular features of a series of 26 patients with chronic large granular NK cell lymphocytosis, whose NK cells were either CD56(-) or expressed very low levels of CD56 (CD56(-/+dim) NK cells), in the context of an aberrant activation-related mature phenotype and proved to be monoclonal using the human androgen receptor gene polymerase chain reaction-based assay. As normal CD56(+) NK cells, CD56(-/+dim) NK cells were granzyme B(+), CD3(-), TCRalphabeta/gammadelta(-), CD5(-), CD28(-), CD11a(+bright), CD45RA(+bright), CD122(+), and CD25(-) and they showed variable and heterogeneous expression of both CD8 and CD57. Nevertheless, they displayed several unusual immunophenotypic features. Accordingly, besides being CD56(-/+dim), they were CD11b(-/+dim) (heterogeneous), CD7(-/+dim) (heterogeneous), CD2(+) (homogeneous), CD11c(+bright) (homogeneous), and CD38(-/+dim) (heterogeneous). Moreover, CD56(-/+dim) NK cells heterogeneously expressed HLA-DR. In that concerning the expression of killer receptors, CD56(-/+dim) NK cells showed bright and homogeneous CD94 expression, and dim and heterogeneous reactivity for CD161, whereas CD158a and NKB1 expression was variable. From the functional point of view, CD56(-/+dim) showed a typical Th1 pattern of cytokine production (interferon-gamma(+), tumor necrosis factor-alpha(+)). From the clinical point of view, these patients usually had an indolent clinical course, progression into a massive lymphocytosis with lung infiltration leading to death being observed in only one case. Despite this, they frequently had associated cytopenias as well as neoplastic diseases and/or viral infections. In summary, we describe a unique and homogeneous group of monoclonal chronic large granular NK cell lymphocytosis with an aberrant activation-related CD56(-/+dim)/CD11b(-/+dim) phenotype and an indolent clinical course, whose main clinical features are related to concomitant diseases.

Clinical features of large granular lymphocyte leukemia

The spectrum of large granular lymphocyte (LGL) proliferations consists of four distinct entities: reactive/transient LGL expansion, chronic LGL lymphocytosis, classical indolent LGL leukemia, and aggressive LGL leukemia. LGL leukemias are classified as lymphoid malignancies. They are divided into CD3(+)/T-cell LGL (85% of cases) and CD3(-)/natural killer (NK) cell LGL leukemia (15% of cases). Recent progress in the comprehension of the leukemogenesis has shown a dysregulation of survival signals in leukemic cells. Identification of LGL expansion has been improved using T-cell receptor (TCR)beta/gamma polymerase chain reaction (PCR) analysis and a combination of Vbeta and killer cell immunoglobulin-like receptor (KIR)-specific monoclonal antibodies. LGL leukemias are characterized by a clonal LGL infiltration of the bone marrow, spleen, and liver. Monoclonality is recognized by phenotypic, molecular, and karyotypic analysis. T-LGL leukemias affect the elderly and display a relatively indolent behavior. Approximately 60% to 70% of patients are symptomatic: recurrent infections secondary to chronic neutropenia, anemia, and autoimmune disease such as rheumatoid arthritis are the main clinical manifestations. Long-lasting remission can be obtained with low-dose methotrexate, cyclosporine A, or cyclophosphamide. Conversely, NK LGL leukemias behave aggressively, and most patients do not respond to chemotherapy.

A unique case of splenic marginal zone-cell lymphoma with synchronous clonal T-cell large granular lymphocyte proliferation: an immunologic, immunohistochemical and genotypic study

We describe a case of synchronous splenic marginal zone-cell lymphoma (SMZL) and T-cell large granular lymphocyte leukemia involving the spleen, liver, bone marrow and peripheral blood. The synchronous occurrence of these two processes was documented by morphological, immunophenotypical and molecular (PCR) analyses of all affected tissues. The pathogenetic mechanisms which may be responsible for the concomitant appearance of these two rather infrequent entities in the same anatomic sites are discussed.

Abnormal NK cell lymphocytosis detected after splenectomy: association with repeated infections, relapsing neutropenia, and persistent polyclonal B-cell proliferation

We report the case of a boy with hereditary spherocytosis who presented with mild microcytic hypochromic anemia and recurrent leg ulcers that had been present since childhood. Chronic natural killer (NK) cell and B-cell lymphocytosis was detected 1 year after therapeutic splenectomy during investigation of recurrent episodes of neutropenia and persistent lymphocytosis. NK cells proved to be abnormal at immunophenotyping studies, and B-cells were polyclonal and displayed a normal immunophenotype. Genotypic analysis of T-cell receptor (TCR)-beta and TCR-gamma genes showed a germ-line pattern. The clinical course of this patient was characterized by multiple pulmonary infections and amygdalitis. We discuss the potential roles of persistent immune stimulation due to chronic hemolysis and severe leg ulcers and of splenectomy in the origin of NK cell lymphocytosis and the relationship between NK cells and recurrent infections, relapsing neutropenia, and polyclonal B-cell response.

Retrospective cohort study of 148 patients with polyclonal gammopathy

OBJECTIVE

To quantify clinical conditions and laboratory values associated with moderate to marked polyclonal gammopathy.

PATIENTS AND METHODS

Patient characteristics, laboratory correlates, evolving disease states, and survival of all patients seen at the Mayo Clinic, Rochester, Minn, during 1991 with a polyclonal gamma globulin level of 3.0 g/dL or higher were reviewed in this retrospective cohort study.

RESULTS

One hundred forty-eight patients were identified (median age, 58 years; 59% female). In 130 patients (88%), only 1 diagnosis was identified. Liver disease was the most common single disease association in 79 (61%) of 130 patients, followed by connective tissue diseases in 28 (22%), chronic infections in 8 (6%), hematologic disorders in 6 (5%), and nonhematologic malignancies in 4 (3%). No difference in gamma globulin levels existed between groups. With a median follow-up of 67 months, 90 (63%) of 143 patients for whom follow-up was available were alive. By multivariate analysis, age, albumin concentration, disease group, and platelet count were predictive of survival. No patient developed myeloma or a clonal plasmaproliferative disorder.

CONCLUSION

Moderate to marked polyclonal gammopathy may reflect an underlying condition: liver disease, connective tissue disease, hematologic disorder, infection, or malignancy.

Current concepts: large granular lymphocyte leukemia

Clonal diseases of large granular lymphocyte (LGL) disorders can arise from a CD3+ T-cell lineage or from a CD3- NK-cell lineage. CD3+ LGL leukemia is the most frequent form of LGL leukemia. T-LGL leukemia usually affects elderly people. Approximately 60% of patients are symptomatic; recurrent infections secondary to chonic neutropenia, anemia, and rheumatoid arthrititis are the main clinical manifestations. The most common phenotype is CD3+, alphabeta+, CD8+, CD57+. Clonality is detected by clonal rearrangement of the T-cell receptor gene. NK-cell LGL proliferative disorders include NK LGL leukemia which is a very aggressive disease and NK chronic lymphocytosis. Serologic findings show frequent reactivity to the BA21 epitope of HTLV-I env p21e, suggesting that a cellular or retroviral protein with homology to BA21 may be important in pathogenesis of these diseases. Clonal expansion may be facilitated by IL12 and IL15 cytokines expressed by leukemic LGL, and also by a defective Fas (CD95) apoptotic pathway. Leukemic LGL constitutively express Fas and Fas-Ligand but they are resistant to Fas-induced apotosis. Neutropenia could be due to soluble Fas-Ligand which is highly secreted in the patient's sera. Clinical and molecular remission can be obtained with oral low-dose methotrexate. Leukemic LGL express a multi-drug resistance phenotype (PgP+/LRP+) that could partly explain the chemoresistance observed in aggressive cases. It is suggested that LGL leukemia can serve as a useful model of dysregulated apoptosis as an underlying mechanism for both malignancy and autoimmune disease.

The immunoregulatory effects of NK cells: the role of TGF-beta and implications for autoimmunity

The cytotoxic activities of natural killer (NK) cells--important in innate immunity--have received considerable attention, but NK cells also regulate T- and B-cell functions as well as hematopoiesis. Here, David Horwitz and colleagues focus on the capacity of NK cells to regulate antibody production positively and negatively, and in particular on the role of NK-cell transforming growth factor beta (TGF-beta) in downregulation of B-cell activity.

Clonal populations of T-cells in patients with B-cell malignancies

Patients with B-cell malignancies are often immunosuppressed and have defective T-cell function in vitro. In addition they frequently have unusual T-cell populations in the peripheral blood including an increase in the number of activated T-cells and an inverted CD4:CD8 ratio. More recently several reports have documented the presence of large, monoclonal populations of T-cells in patients with paraproteinaemia, B-CLL and hairy cell leukemia. Such cells can reach very high levels in the peripheral blood, occasionally representing over 50% of all CD8+ T-cells. These clonally expanded cells have a characteristic morphology and phenotype in that they are often large, granular cells with natural killer cells markers. Their properties have not been studied in detail but they appear to suppress immunoglobulin production and kill cell targets in an MHC-unrestricted manner. The relationship of clonal T-cells to the B-cell tumour is unclear. They may be directly interacting with the malignant clone or alternatively be nonspecifically activated secondary to a disruption of the immune homeostasis by tumour cells. If they indeed represent an attempt by the immune response to control the malignant cells it is possible that they may be utilised in future attempts at immunotherapy.

T cell receptor alpha-chain and beta-chain junctional region homology in clonal CD3+, CD8+ T lymphocyte expansions in Felty's syndrome

OBJECTIVE

Up to 42% of patients with Felty's syndrome (FS) have peripheral blood expansions of CD3+,CD8+ large granular lymphocytes (LGLs). The aim of this study was to determine whether the T cell receptor (TCR) alpha- and beta-chain sequences of these expansions from different patients have features in common that would support the hypothesis of an antigen-driven process.

METHODS

Extraction of RNA from peripheral blood lymphocytes followed by synthesis of complementary DNA, inverse polymerase chain reaction (PCR) with TCR-specific primers, bacteriophage transformation, and sequencing of PCR products.

RESULTS

Structural analysis of TCR beta-chain usage in such patients demonstrated a junctional region motif comprising the amino acids -LG- or -RG- in 7 of 14 clonal sequences and the motif -GXG- in 8 of 14. A biased alpha-chain junctional region usage of a hydrophobic and/or basic amino acid at position 2 was seen in 5 of 8 expanded sequences. These features differed significantly from control sequences.

CONCLUSION

Given current models of TCR-peptide-major histocompatibility complex interaction, these observations are consistent with an antigen-driven, rather than a superantigen-driven, process in at least a subgroup of patients with FS.

Humoral immune abnormalities in T-cell large granular lymphocyte leukemia

The prevalence of humoral immune dysfunction has not been defined in a large series of patients with T-cell large granular lymphocyte leukemia (T-LGL) confirmed to be clonal by T-cell receptor analysis. Therefore we evaluated the presence of multiple autoantibodies in 27 patients with this disease. Humoral immune abnormalities included: rheumatoid factor (RF) (15/27 patients), antinuclear antibody (ANA) (13/27 patients), polyclonal hypergammaglobulinemia (15/24 patients), elevated serum immunoglobulins (17/26 patients), immune complex formation (18/25 patients), elevated beta-2 microglobulin (13/18 patients) and neutrophil-reactive IgG (18/20 patients). Disease manifestations in these patients were due to complications of cytopenia or autoimmune abnormalities. Infection was a common finding (21/27 patients) and likely reflected their neutropenia. Rheumatoid arthritis (11/27 patients), anemia (12/27 patients) and thrombocytopenia (10/27 patients) were less common but still frequently observed. This study demonstrates the presence of multiple autoantibodies in a large series of patients with documented clonal T-LGL proliferations.

Resolution of autoimmune hemolytic anemia following splenectomy in CD3+ large granular lymphocyte leukemia

A 24 year old female with a 4 year history of anemia and absolute lymphocytosis was evaluated and found to have T cell large granular lymphocyte (T-LGL) leukemia associated with autoimmune hemolytic anemia, neutropenia, mild thrombocytopenia and splenomegaly. In an effort to ameliorate her symptomatic cytopenias, she was treated with prednisone and subsequently methotrexate without success. In February 1993, she underwent splenectomy for symptomatic anemia. Splenectomy resulted in an increased hemoglobin concentration to normal levels, resolution of all laboratory evidence of hemolysis, and disappearance of thrombocytopenia. This response has been durable despite persistence of the abnormal LGL clone. We suggest that splenectomy may be an effective treatment for autoimmune hemolytic anemia and/or thrombocytopenia often associated with T-LGL leukemia. As this disease often exhibits a chronic clinical course with morbidity resulting from consequences of resultant cytopenias rather than visceral involvement with leukemic LGL, effective treatment of cytopenias despite persistence of the abnormal LGL clone is beneficial.

Chronic natural killer cell lymphocytosis

Chronic proliferations of natural killer (NK) cells (CD3- CD16+) are identified initially by detecting large granular lymphocyte (LGL) excess in a peripheral blood smear and subsequent lymphocyte immunophenotyping by flow cytometry. A related disease, T-LGL leukemia, has an indolent clinical course with chronic neutropenia and a close association with rheumatoid arthritis. Herein are described the clinical presentation and long-term clinical course of patients with chronic NK cell lymphocytosis (CNKL). The majority of the 14 patients followed up for a median of 4 years presented with severe cytopenias or vasculitic syndromes that were responsive to immunosuppressive therapy. Other manifestations included fever and arthralgias. In general, the disease was nonprogressive and had a course similar to that of T-LGL leukemia.

Silicone-induced modulation of natural killer cell activity

Current controversy regarding the effects of silicone gel mammary implants on the immune system has led to increased focus on the potential biological activity of silicone materials. Studies were undertaken in the B6C3F1 mouse to evaluate the immunotoxicological effects of the following components of a mammary gel prosthesis: polydimethylsiloxane fluid, silicone gel, elastomer shell and a polyurethane implant cover. Material was implanted subcutaneously (s.c.) for either 10 or 180 days. The only toxicological or immunological parameter which differed from control values was the natural killer (NK) cell activity in gel implanted mice. In these animals, basal NK activity was decreased. NK activity was comparably inhibited in female Fischer 344 rats implanted with silicone gel following short term (14 or 30 days) as well as chronic (1 year) exposure. The response was variable in both the rat and mouse. Host resistance to B16F10 melanoma in the mouse is known to be related to NK activity. Despite suppression of NK activity following gel implantation, host resistance was unaltered. Inhibition of NK activity by the administration of anti-asialo GM1 indicated that resistance was not adversely affected until NK activity was decreased by 40 to 50%. As with basal NK activity, augmented NK activity was inhibited in gel implanted rats when compared to controls. Administration of polyinosinic:polycytidylic acid to gel implanted rats resulted in an increase of approximately 65% in NK activity compared to gel implanted controls. This level of augmented NK activity was significantly less than the level of augmented NK activity in vehicle implanted animals where 100% enhancement in NK activity was noted. The results of these studies indicate that (1) NK cytolytic activity is altered in two animal models, the mouse and rat, although the results were variable, that (2) the level of suppression noted in the mouse is ineffective when compared to the level of suppression required to alter host resistance to B16F10 melanoma and that (3) the gel implanted animals exhibit a suppressed response to NK augmentation.

Longstanding proliferation of CD3 negative large granular lymphocytes preceding the development of high grade non-Hodgkin's lymphoma

A patient with a persistent CD3 negative large granular lymphocyte (LGL) proliferation with immunophenotypic and functional characteristics of natural killer cells is described. The LGL proliferation persisted and six years after diagnosis the patient developed a high grade B cell non-Hodgkin's lymphoma. Molecular studies demonstrated clonal B cell populations in the peripheral blood, distinct from that identified in the lymphoma, both at presentation with non-Hodgkin's lymphoma and at complete remission following combination chemotherapy. It is postulated that T cell dysregulation associated with the CD3 negative LGL proliferation may have led to B cell dysfunction and loss of normal B cell control, with the subsequent development of a clonal B cell lymphoproliferative disorder.

T-cell large granular lymphocytic leukemia and pure red cell aplasia in a patient with type I autoimmune polyendocrinopathy: response to immunosuppressive therapy

Clonal proliferations of large granular lymphocytes (LGLs) of T-cell origin characterize T-cell LGL leukemia. This disorder has been described in association with rheumatoid arthritis and other autoimmune phenomena. The presence of endocrinologic abnormalities in patients with T-cell LGL leukemia has not been previously reported, nor has T-cell LGL leukemia been described in patients with endocrinologic abnormalities. Herein we describe a young woman with type I autoimmune polyendocrinopathy, in whom pure red cell aplasia developed in association with clonal proliferation of LGLs. Immunosuppressive therapy with cyclophosphamide resulted in remission of pure red cell aplasia, transient improvement in hypocalcemia, and disappearance of the LGL clone. Clonal proliferation of LGLs may be associated with autoimmune endocrinopathies. Clinicians who are responsible for the care of such patients should be aware of this possible association.

Etiology of neutrophilic granulocytic hypoplasia in a case of large granular lymphocytic leukemia with paraproteinemia

The association between large granular lymphocytic leukemia (LGLL) and neutropenia is poorly understood. We attempted to assess whether neutropenia in LGLL with paraproteinemia has a different etiology than LGLL without paraproteinemia. We found neither direct serum inhibition of granulocyte/monocyte-colony forming units in vitro nor increased immunoglobulin binding to granulocytic neutrophils, neutrophil precursors, or granulocyte/monocyte-colony stimulating factor. Clonogenic assay experiments suggested that suppression of the patient's granulocyte/monocyte-colony forming units by the neoplastic T-cells and decreased granulocyte/monocyte-colony stimulating factor production contributed to the pathogenesis of neutropenia in this particular case.

Lymphoproliferative disease of "LAK cell" precursor large granular lymphocytes in association with celiac disease

We have investigated a case of lymphoproliferative disease of large granular lymphocytes (LDGL) occurring in association with celiac disease, anemia, neutropenia, and carcinomas of the endometrium, breast, and skin. The large granular lymphocyte (LGL) proliferation was monoclonal, T cell in origin, with T cell receptor beta-chain gene rearrangement, and a CD3+, CD8+, CD16+/- phenotype. In spite of the high frequency of LGL, natural killer (NK) cell activity was absent. Stimulation with interleukin-2 in vitro, however, resulted in high lymphokine-activated killer (LAK) cell activity against NK-resistant targets. The T-cell nature of the LAK precursor cells is in contrast to the majority seen in normal peripheral blood. Therapeutic trials of cyclosporin A, low-dose cyclophosphamide, and levamisole were unsuccessful in reducing transfusion requirements. This case is unique in the association of LDGL with celiac disease. It is also unique in that the patient had been followed for several years prior to the onset of the LDGL. The case extends the list of lymphoproliferative disorders documented to be associated with celiac disease and, conversely, adds to our knowledge of lymphoproliferative disorder of LGL and its "dysimmune" manifestations.

[Lymphoproliferative syndrome with granular lymphocytes of CD8+ phenotype: a clonal pathology with a chronic course]

The syndrome of CD8 hyperlymphocytosis with neutropenia is a heterogeneous disorder ranging from reactive benign state to neoplastic pathology. The prognosis for LGL (Large Granular Lymphocyte) leukemia depends likely on its phenotype:-NK phenotype, extremely poor prognosis and rapidly fatal-T phenotype (CD8+), chronic disease with slow progression. Here, we report four cases of CD8+ hyperlymphocytosis with neutropenia, which are CD2+/-, CD3+, CD4-, CD8+, CD16-, CD56+/-, CD57+ phenotype. These lymphocytic proliferations were associated with clonal rearrangement of T-cell receptor b gene. In two cases, characteristic blood hyperlymphocytosis appeared only after splenectomy, but retrospective bone marrow analysis showed that the CD8+, CD57+ lymphocyte proliferation previously existed. These lymphocytes had a low natural killer activity against K562 cell line. HTLV1 proviral sequence was not integrated in leukemic cell DNA. This monoclonal pathology has a chronic clinical course, with a thirteen year evolution in one case. Splenectomy did not correct neutropenia but allowed the control of hemolytic anemia and auto-immune thrombocytopenia in one case.

Felty's and pseudo-Felty's syndromes

Felty's syndrome, consisting of rheumatoid arthritis, leukopenia, and splenomegaly, has been recognized as a distinct clinical entity for more than 60 years. Clinical and laboratory manifestations of the condition are reviewed. The major sources of morbidity and mortality remain recurrent local and systemic infections. Immunogenetic analysis shows a strong association with HLA-DR4, in addition to DQ beta 3b and C4B null allele. Potential mechanisms of neutropenia are contrasted, including impaired granulopoiesis and neutrophil-immune complex interactions. Lithium carbonate and splenectomy may have a role in the treatment of fulminant disease. Maintenance therapy should be directed at control of the underlying inflammatory arthropathy. A syndrome of proliferation of large granular lymphocytes and neutropenia, associated with rheumatoid arthritis in 23% to 39% of cases, has been described recently. Cases of "pseudo-Felty's" syndrome are often confused with traditional Felty's syndrome, which has twice the prevalence. The clinical and laboratory distinctions between these two conditions are elaborated.