Adult-onset cyclic neutropenia is a benign neoplasm associated with clonal proliferation of large granular lymphocytes.

Human cyclic neutropenia occurs in children and adults. Adult-onset cyclic neutropenia is an acquired disease characterized by increased numbers of large granular lymphocytes (LGL), in contrast to childhood-onset cyclic neutropenia in which LGL counts are normal. We investigated the clonality of lymphocytes in these two groups of patients by assessing the rearrangement status of the T cell receptor beta chain gene. Patients with adult-onset cyclic neutropenia showed clonal rearrangement of the T beta gene whereas the children did not. Since LGL are known to have multiple regulatory effects on normal hematopoiesis, the finding of a clonal proliferation of this lymphocyte population implicates these cells in the pathogenesis of cyclic neutropenia.

Clinical spectrum of gammadelta+ T cell LGL leukemia: analysis of 20 cases.

We report on the clinico-biological characteristics of 20 cases of gammadelta T cell large granular lymphocyte (LGL) leukemia. All the data were compared to that of 196 cases with alphabeta T cell subtype, which represents the majority of T cell LGL leukemias. Clinical findings were quite similar in the two groups regarding age, sex ratio, recurrent infections, and association with auto-immune diseases especially rheumatoid arthritis. Gammadelta LGL predominantly expressed a CD3+/CD4-/CD8+/CD16+/CD57+ phenotype, in 50% of cases. Clinical outcome was favorable for these patients with overall survival of 85% at 3 years. Fifty percent of gammadelta patients required treatment and the response to therapy was estimated at 55%. gammadelta and alphabeta T cell LGL leukemia harbor a very similar clinico-biological behavior and represent part of an antigen-driven T cell lymphoproliferation.

Inhibition of STAT3 signaling leads to apoptosis of leukemic large granular lymphocytes and decreased Mcl-1 expression.

Large granular lymphocyte (LGL) leukemia is characterized by the expansion of antigen-activated cytotoxic T lymphocytes. These leukemic cells are resistant to Fas-mediated apoptosis despite expressing high levels of Fas. We found that leukemic LGL from 19 patients displayed high levels of activated STAT3. Treatment of leukemic LGL with the JAK-selective tyrosine kinase inhibitor AG-490 induced apoptosis with a corresponding decrease in STAT-DNA binding activity. Moreover, using an antisense oligonucleotide approach to diminish STAT3 expression, we found that Fas sensitivity was restored in leukemic LGL. AG-490-induced apoptosis in leukemic LGL was independent of Bcl-xL or Bcl-2 expression. However, we found that the Bcl-2-family protein Mcl-1 was significantly reduced by AG-490 treatment. Activated STAT3 was shown to bind an SIE-related element in the murine mcl-1 promoter. Using a luciferase reporter assay, we demonstrated that v-src overexpression in NIH3T3 induced STAT3-dependent transcriptional activity from the mcl-1 promoter and increased endogenous Mcl-1 protein levels. We conclude that STAT3 activation contributed to accumulation of the leukemic LGL clones. These findings suggest that investigation should focus on novel strategies targeting STAT3 in the treatment of LGL leukemia.

Activation of leukemic large granular lymphocytes by interleukin-2 via the p75 interleukin-2 receptor.

We studied the role of interleukin-2 (IL-2) receptor subunits in the activation of leukemic CD3+ large granular lymphocytes (LGL). Peripheral blood mononuclear cells from four patients with CD3+ LGL leukemia were activated with 500 mu/ml of recombinant IL-2. Induction of both proliferative and cytotoxic functions by IL-2 was blocked by addition of anti-p75 IL-2 receptor monoclonal antibody, but not by addition of anti-p55 IL-2 receptor monoclonal antibody. Sorting experiments demonstrated directly that the effects of the anti-p75 IL-2 receptor monoclonal antibody were on leukemic LGL. These results show constitutive expression of functional p75 IL-2 receptors on leukemic LGL and suggest a possible mechanism for leukemic LGL proliferation in vivo.

Serologic and molecular evidence for a possible pathogenetic role of viral infection in CD3-negative natural killer-type lymphoproliferative disease of granular lymphocytes.

We studied a series of 18 patients with CD3- lymphoproliferative disease of granular lymphocytes (LDGL) for evidence of chronic viral infection, including Epstein-Barr (EBV), hepatitis B (HBV), hepatitis C (HCV), human T lymphotropic virus (HTLV), and human immunodeficiency virus (HIV). Although all patients tested had serologic evidence for past infection with EBV, polymerase chain reaction (PCR) analysis of peripheral blood mononuclear cell (PBMC) DNA utilizing specific EBV primers demonstrated the presence of EBV-DNA in only six of 17 CD3- LDGL cases. A previous history of HBV infection, as defined by the presence of circulating IgG anti-HBc antibodies associated with either HBsAg positivity or negativity, was documented in seven cases; however, viral DNA was not detected in PBMC of these patients using PCR with specific HBV primers. Specific anti-HCV antibodies, confirmed by recombinant immunoblot assay, were detected in five CD3- LDGL patients; PCR analysis demonstrated the presence of viral RNA in PBMC of two of these cases. No patient had antibodies to HTLV-I/II or HIV-1/2. Five patients were infected by more than one virus (two with HBV and EBV and three with HBV and HCV). Our results provide serologic evidence for past viral infection in the large majority of CD3- NK-type LDGL patients. These data suggest that viral infection may have played a role early in disease pathogenesis and may no longer be necessary in sustaining GL proliferation in CD3- NK-type LDGL.

Inhibition of canine NK activity by anti-CD18 monoclonal antibody, UV irradiation and cyclosporine.

Previous studies from our laboratory have shown that large granular lymphocytes (LGL) mediate natural killer cell (NK) activity in dogs and that host LGL are associated with graft failure in a canine model of histoincompatible marrow transplantation. We now report studies on the effects of anti-CD18 monoclonal antibody (MAB) 60.3, ultraviolet (UV) irradiation and cyclosporine (CSP) on in vitro canine NK function. Treatment with the murine anti-CD18 MAB 60.3 produced marked diminution in lytic function (mean 79% inhibition). UV irradiation at doses greater than 1.6 millijoules/cm2 completely eliminated NK function; this effect was not due to defective effector/target conjugate formation. CSP also inhibited NK function, although in vitro lytic activity was not completely blocked (mean of 44% inhibition) at concentrations which correspond to those achieved in vivo (400 ng/mL). These observations form a basis for future investigations aimed at preventing graft failure in the canine model of histoincompatible marrow transplantation by blocking NK function in vivo.

'Resistance' to unrelated, DLA-nonidentical canine marrow grafts is unrestricted by the major histocompatibility complex.

Dogs undergoing rejection of unrelated, dog leukocyte antigen (DLA)-nonidentical marrow grafts show an increase in mononuclear cell counts in the peripheral blood at 1 week after transplant. Cells are of host origin and express phenotypic and morphologic characteristics of large granular lymphocytes (LGLs). LGLs from rejecting dogs suppress in vitro growth of donor marrow colony-forming units-granulocyte/macrophage (CFU-GM) and have natural killer (NK) cell activity. The current study tested whether the marrow-suppressive activity of LGLs obtained at the time of marrow graft rejection was major histocompatibility complex (MHC)-restricted. Five dogs were in the process of rejecting their DLA-nonidentical unrelated marrow grafts after conditioning with 9.2 Gy total-body irradiation (TBI). At the time of rejection, peripheral blood mononuclear cells (PBMC) were harvested. PBMC were co-cultured with marrow obtained from the original marrow transplant donor and from other unrelated dogs that were either DLA-identical or -nonidentical with the marrow donor. A statistically significant reduction of marrow donor CFU-GM was seen when compared to results with autologous effector PBMC from the marrow donor. The number of colonies with recipient effector PBMC ranged from 8 to 75% (median 29%). No suppression was seen with PBMC effectors from unrelated DLA-identical or DLA-nonidentical dogs. Similarly, significant reductions in the number of CFU-GM compared to autologous controls were seen with effector PBMC from marrow recipients and marrow target cells, both from unrelated dogs that were phenotypically DLA-identical or -nonidentical with the marrow donor. The number of colonies ranged from 6 to 68% (median 29%) and 1 to 102% (median 20%), respectively. NK activity was present at low levels in all recipients, while specific alloantigen-primed cytotoxic T cell killing by cells obtained from the five recipients yielded cytolysis of donor PBMC in only one case, suggesting that the marrow-suppressive activity was NK cell-mediated. In conclusion, PBMC from canine marrow transplant recipients undergoing rejection of DLA-nonidentical marrow grafts suppress in vitro CFU-GM growth of marrow donor cells, and this suppression is not MHC-restricted.

Splenectomy does not enhance engraftment of DLA-nonidentical marrow transplants.

Previous studies in mice and monkeys suggested that either splenic irradiation of splenectomy led to enhanced allogeneic marrow engraftment. These findings suggested that a population of radiation-resistant host cells involved in mediating marrow graft rejection are sequestered in the spleen. In this current study, the effect of splenectomy in dogs receiving 9.2 Gy total body irradiation (TBI) and unrelated dog leukocyte antigen (DLA)-nonidentical donor marrow grafts was studied. We found that splenectomy did not significantly change the incidence of graft failure as compared to that observed in previously and concurrently transplanted nonsplenectomized recipients.

Transfusion of autologous cytotoxic cells leads to failure of unrelated, DLA-nonidentical marrow grafts.

Dogs conditioned with 9.2 Gy total body irradiation (TBI) and given histoincompatible marrow transplants have a high rate of graft failure. Engraftment can be achieved by using 18 Gy fractionated TBI as preparative regimen. In this study, we tested the effects of infusing, at the time of histoincompatible marrow transplantation, autologous cells that had been stored before beginning high-dose (18 Gy) TBI. Our aim was to identify the peripheral blood mononuclear cells (PBMC) that contribute to failure of marrow grafts. Marrow graft failure was observed in three of three dogs receiving a mean of 2.1 x 10(8) unfractionated autologous PBMC/kg body weight as well as in two of two dogs receiving a mean dose of 0.075 x 10(8) PBMC/kg. When the dose of PBMC was decreased to 0.01 x 10(8)/kg, engraftment was seen in two of two dogs. These experiments thus established a cell dose response for causing marrow graft failure; further studies evaluated which subset of cells mediated this effect. Infusion of 0.09 x 10(8) nylon wool-nonadherent, plastic-nonadherent PBMC/kg was effective in causing marrow graft failure in three of three dogs. In contrast, infusion of 0.03 x 10(8) autologous monocytes/kg, enriched threefold above the number contained in the lower dose of PBMC causing graft failure, was associated with engraftment in four of six dogs. Infusion of 0.13 x 10(8) PBMC/kg treated with L-leucyl-L-leucine methyl ester (Leu-Leu-OMe), a drug that depletes canine cytotoxic T-lymphocytes (CTL), natural killer (NK) cells, and monocytes, permitted engraftment in three of four dogs. These data suggest that cytotoxic lymphocytes mediate failure of histoincompatible marrow grafts.

HTLV-1 Tax deregulates autophagy by recruiting autophagic molecules into lipid raft microdomains.

The retroviral oncoprotein Tax from human T-cell leukemia virus type 1 (HTLV-1), an etiological factor that causes adult T-cell leukemia and lymphoma, has a crucial role in initiating T-lymphocyte transformation by inducing oncogenic signaling activation. We here report that Tax is a determining factor for dysregulation of autophagy in HTLV-1-transformed T cells and Tax-immortalized CD4 memory T cells. Tax facilitated autophagic process by activating inhibitor of κB (IκB) kinase (IKK) complex, which subsequently recruited an autophagy molecular complex containing Beclin1 and Bif-1 to the lipid raft microdomains. Tax engaged a crosstalk between IKK complex and autophagic molecule complex by directly interacting with both complexes, promoting assembly of LC3+ autophagosomes. Moreover, expression of lipid raft-targeted Bif-1 or Beclin1 was sufficient to induce formation of LC3+ autophagosomes, suggesting that Tax recruitment of autophagic molecules to lipid rafts is a dominant strategy to deregulate autophagy in the context of HTLV-1 transformation of T cells. Furthermore, depletion of autophagy molecules such as Beclin1 and PI3 kinase class III resulted in impaired growth of HTLV-1-transformed T cells, indicating a critical role of Tax-deregulated autophagy in promoting survival and transformation of virally infected T cells.

Immunosuppressive therapy of LGL leukemia: prospective multicenter phase II study by the Eastern Cooperative Oncology Group (E5998).

Failure to undergo activation-induced cell death due to global dysregulation of apoptosis is the pathogenic hallmark of large granular lymphocyte (LGL) leukemia. Consequently, immunosuppressive agents are rational choices for treatment. This first prospective trial in LGL leukemia was a multicenter, phase 2 clinical trial evaluating methotrexate (MTX) at 10 mg/m(2) orally weekly as initial therapy (step 1). Patients failing MTX were eligible for treatment with cyclophosphamide at 100 mg orally daily (step 2). The overall response in step 1 was 38% with 95% confidence interval (CI): 26 and 53%. The overall response in step 2 was 64% with 95% CI: 35 and 87%. The median overall survival for patients with anemia was 69 months with a 95% CI lower bound of 46 months and an upper bound not yet reached. The median overall survival for patients with neutropenia has not been reached 13 years from study activation. Serum biomarker studies confirmed the inflammatory milieu of LGL but were not a priori predictive of response. We identify a gene expression signature that correlates with response and may be STAT3 mutation driven. Immunosuppressive therapies have efficacy in LGL leukemia. Gene signature and mutational profiling may be an effective tool in determining whether MTX is an appropriate therapy.

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.

Large granular lymphocyte leukemia. Report of 38 cases and review of the literature.

LGL leukemia results from a chronic, clonal proliferation of LGL. Chronic neutropenia with recurrent bacterial infection and splenomegaly are common clinical manifestations. Rheumatoid arthritis coexists in some of these patients, who thus resemble patients with Felty syndrome. Other hematologic abnormalities that may occur include pure red-cell aplasia and adult-onset cyclic neutropenia. Lymphoid infiltration of bone marrow, splenic red pulp cords, and hepatic sinusoids is characteristic; lymph node and skin involvement are rare. Multiple serologic abnormalities are frequently present, including positive tests for rheumatoid factor and/or antinuclear antibody, polyclonal hypergammaglobulinemia, and circulating immune complexes. Antineutrophil and antiplatelet antibodies are often present. Leukemic LGL exhibit phenotypic heterogeneity; the most common phenotype in our patients is CD2+, CD3+, CD8+, HNK-1+, CD16-. Despite markedly increased numbers of LGL, functional activity of the cells is usually decreased. The mechanism of cytopenias is uncertain: in pure red-cell aplasia, it appears to be due to suppressive effect on erythropoiesis by abnormal LGL, but in patients with chronic neutropenia it may be antibody-mediated. Although most patients appear to have a relatively benign clinical course, mortality from infections and progressive lymphoproliferation is substantial. Optimal therapy remains undefined. Some preliminary evidence suggests that LGL leukemia may be associated with infection with a retrovirus similar to HTLV-I. Although relatively rare, LGL leukemia is of interest because a better understanding of this disease process may contribute to our knowledge of autoimmune diseases, the immunoregulatory functions of LGL, and the mechanisms controlling normal hematopoiesis.

The quality of medical evidence in hematology-oncology.

PURPOSE: The purpose of this study was to evaluate the quality of the medical evidence available to the clinician in the practice of hematology/oncology. METHODS: We selected 14 neoplastic hematologic disorders and identified 154 clinically important patient management decision/interventions, ranging from initial treatment decisions to those made for the treatment of recurrent or refractory disease. We also performed a search of the scientific literature for the years 1966 through 1996 to identify all randomized controlled trials in hematology/oncology. RESULTS: We identified 783 randomized controlled trials (level 1 evidence) pertaining to 37 (24%) of the decision/interventions. An additional 32 (21%) of the decision/interventions were supported by evidence from single arm prospective studies (level 2 evidence). However, only retrospective or anecdotal evidence (level 3 evidence) was available to support 55% of the identified decision/interventions. In a retrospective review of the decision/interventions made in the management of 255 consecutive patients, 78% of the initial decision/interventions in the management of newly diagnosed hematologic/oncologic disorders could have been based on level 1 evidence. However, more than half (52%) of all the decision/interventions made in the management of these 255 patients were supported only by level 2 or 3 evidence. CONCLUSIONS: We conclude that level 1 evidence to support the development of practice guidelines is available primarily for initial decision/interventions of newly diagnosed diseases. Level 1 evidence to develop guidelines for the management of relapsed or refractory malignant diseases is currently lacking.

Correlation of hypomagnesemia with the onset of cyclosporine-associated hypertension in marrow transplant patients.

Cyclosporine is known to cause hypertension, and we have recently reported that it causes hypomagnesemia and renal magnesium wasting in marrow transplant recipients. We performed a case-control study to ask whether hypomagnesemia might be related to this form of drug-induced hypertension. The charts of 188 patients treated with cyclosporine were evaluated for the development of hypertension. The 32 patients who became hypertensive were age, sex, and disease-matched with 32 cyclosporine-treated controls. Baseline serum Mg levels were normal in both groups. However at the time of development of hypertension, the hypertensive patients had a mean (+/- SD) Mg of 1.22 +/- 0.20 mEq/L versus controls 1.40 +/- 0.33 mEq/L (P less than 0.01). Serum calcium, albumin, creatinine, potassium, and cyclosporine concentrations were not different between the two groups. This study may indicate that hypertension and hypomagnesemia are coincident toxicities in cyclosporine-treated patients. Alternatively, our data support the hypothesis that acquired derangements in magnesium metabolism may contribute to the development of hypertension. Magnesium replacement may prove beneficial in the treatment and/or prevention of cyclosporine-associated hypertension.

Facilitation of engraftment of DLA-nonidentical marrow by treatment of recipients with monoclonal antibody directed against marrow cells surviving radiation.

Past studies in dogs have suggested that marrow graft rejection was mediated by major histocompatibility complex (MHC) class II antigen-positive non-T cells that survived standard doses of total-body irradiation (TBI). We have now raised 4 monoclonal antibodies (mAbs) against marrow cells harvested 6 days after TBI. The mAbs are highly reactive (greater than 70%) with marrow cells surviving radiation and also bind strongly (greater than 50%) to normal marrow cells, lymphocytes, monocytes, and granulocytes. One of the mAbs (34-S3) reacted strongly with NK-like cells. In vitro treatment of marrow with mAb and rabbit complement (C') did not affect erythroid colony-forming unit (CFU-E) growth, whereas 2 of the 4 mAbs inhibited granulocyte-macrophage colony-forming unit (CFU-GM) growth, and all 3 mAbs tested suppressed autologous marrow engraftment. One of the mAbs, 69-S5 (IgG1), bound to a 95,000 dalton antigen. It crossreacted with human cells, but not with cells from Rhesus monkeys, baboons, and cats. We administered this mAb intravenously at 0.2 mg/kg/day on days -5 to 0 to dogs given 9.2 Gy TBI on day 0 followed by marrow grafts (less than or equal to 4 x 10(8) cells/kg) from DLA-nonidentical unrelated donors. Three of five dogs had sustained grafts. Increasing the dose of mAb ten-fold (2 mg/kg/day) resulted in graft failure (2 of 2 dogs). Treatment with a dose of 0.2 mg/kg/day from day -7 to -2 showed sustained engraftment in 7 of 10 dogs. This result is in contrast to sustained grafts in 3 of 36 dogs not given mAb, and in 1 of 7 dogs treated with an irrelevant mAb (P = 0.0002 and 0.04, respectively). We conclude that treatment of recipients with a mAb raised against marrow cells surviving radiation and not directed at major histocompatibility complex (MHC) class II antigens and NK-like cells can also facilitate engraftment of DLA-nonidentical canine marrow. These results may be relevant for the transplantation of HLA-incompatible marrow in man, particularly after in vivo T cell depletion, where graft failure is frequent.

Treatment of human acute graft-versus-host disease with antithymocyte globulin and cyclosporine with or without methylprednisolone.

Forty-eight patients with hematologic malignancies treated by allogeneic marrow transplantation developed acute graft-versus-host disease (GVHD), grades II-IV, despite prophylaxis with methotrexate. They were treated with a combination of antithymocyte globulin (ATG) and cyclosporine (CsA), with or without the addition of methylprednisolone (MP). Thirty patients had received HLA-identical and 18 HLA-nonidentical transplants. Median onset of GVHD was day 13 (range 8-60) for patients with HLA-nonidentical grafts and day 18 (range 7-48) for patients given HLA-identical grafts (P = 0.01). Forty-five patients could be evaluated for response on day 7 of therapy. Among these, 13 of 27 given ATG/CSP and 6 of 18 given ATG/CSP/MP improved. Among 33 patients evaluable on day 14 of therapy 13 of 19 given ATG/CSP and 5 of 14 given ATG/CSP/MP showed improvement of GVHD. Patients given HLA-nonidentical grafts responded somewhat (although not significantly) less frequently than patients given HLA-identical grafts. Chronic GVHD developed in 16 of 18 evaluable patients given ATG/CSP and in 5 of 6 given ATG/CSP/MP. Viral, bacterial, and fungal infections were the major cause of death in both groups. Interstitial pneumonitis was more frequent among patients given ATG/CSP/MP. Survival beyond 6 months was 67% among patients treated with ATG/CSP and 25% with ATG/CSP/MP. These data indicate that a regimen of ATG/CSP is of value in the treatment of acute GVHD. The addition of MP was not beneficial and resulted in decreased survival--presumably because of excessive immunosuppression and associated complications.

Prototypical HTLV-I/II infection is rare in LGL leukemia.

The etiology of LGL leukemia is not known; however, we recently detected HTLV-II in a patient with LGL leukemia. In this study, we found that sera from 6 of 28 patients with LGL leukemia were positive for HTLV-I/II using a whole virus ELISA; moreover, the ELISA-negative sera were near the positive cut-off value. Therefore, we performed additional studies on these sera using commercially available assays which can confirm and distinguish HTLV-I from HTLV-II infection. Serum from only one patient was confirmed positive using conventional criteria (HTLV-II+). Sera from 25 patients (89%) had indeterminate reactivity on Western blot assays. Of these, sera from 21 (84%) reacted to gag protein p24; 12 (48%) reacted with recombinant env protein p21e, and 10 (40%) reacted with both. We could not detect HTLV-I/II pol or pX gene sequences in these patients using polymerase chain reaction analyses, with the exception of the HTLV-II-infected patient described previously. These data show that most patients with LGL leukemia are not infected with prototypical HTLV-I or HTLV-II. The frequent reactivity of patient sera to HTLV-I/II gag protein p24 and to env protein p21e, however, suggests that a deleted or variant form of HTLV-I/II may be associated with LGL leukemia.

The pathology of large granular lymphocyte leukemia.

The authors conducted a histopathologic study on tissues from 11 patients with the recently described syndrome of large granular lymphocyte (LGL) leukemia. Distinctive pathologic findings were found most often in the bone marrow, liver, and spleen. The bone marrow biopsies contained nonparatrabecular lymphoid infiltrates that were nodular or diffuse and interstitial. Plasmacytosis was found and in two cases there was myeloid maturation arrest. The liver biopsies contained sinusoidal and portal infiltrates and the spleen had red pulp cord and sinus infiltrates, plasmacytosis, and follicular hyperplasia. Lymph node involvement was nondiagnostic, consistent with the usual absence of lymphadenopathy. The morphologic findings were sometimes indistinguishable from other reactive or low-grade lymphoproliferative disorders, especially chronic lymphocytic leukemia/well-differentiated lymphocytic lymphoma (CLL/WDLL) and hairy cell leukemia. These results suggest the need to correlate peripheral blood cell counts and morphology as well as immunophenotypic studies with tissue histology to distinguish LGL leukemia from other disorders. Establishing a correct diagnosis of LGL leukemia may help clarify the etiology of unexplained peripheral blood cytopenias, arthritis, and other autoimmune manifestations in individual patients.

Seroprevalence of HTLV-I and HTLV-II in marrow transplant recipients.

HTLV-I and HTLV-II can both be transmitted through blood transfusions. Although the seroprevalence of HTLV-I/II in volunteer blood donors in low, patients with leukemia who received multiple blood transfusions are at increased risk for HTLV-I/II infection. Patients undergoing marrow transplantation for malignant and non-malignant diseases have often received multiple transfusions prior to transplantation. The seroprevalence of HTLV-I/II in marrow transplant recipients is not known, however. We studied pre-transplant sera from 317 patients receiving allogeneic or syngeneic marrow transplant in 1988 for antibodies to HTLV-I/II using an ELISA. Six sera were positive in this assay and nine other sera had absorbance values elevated above background. One of these 15 sera was confirmed positive in a Western blot assay; six others had an indeterminate reactivity. The seropositive patient was infected with HTLV-I and not HTLV-II as determined using a synthetic peptide-based ELISA; the indeterminate sera did not show reactivity to either HTLV-I or HTLV-II in this assay. Differentiation of HTLV-I from HTLV-II infection was also shown using a modified recombinant Western blot assay in which the seropositive patient showed reactivity to recombinant HTLV-I env gp46 and not recombinant HTLV-II env gp46. These results show infection with HTLV in one of 317 patients (0.3%) prior to marrow transplantation. The clinical consequences resulting from HTLV-I/II seropositivity during the severe immunosuppression accompanying marrow transplantation are not known. Testing blood donors for HTLV-I/II as is currently practised should reduce seroprevalence of HTLV-I/II in previously transfused marrow transplant recipients.