Hairy cell leukaemia of T-cell origin

Hairy cell leukaemia

Hairy cell leukaemia is a rare chronic lymphoproliferative disease, characterized by splenomegaly, pancytopenia and recurrent infection. The characteristic 'hairy cells', present in the peripheral blood and bone marrow, are the hallmark of this leukaemia. The disease has a chronic, progressive course, and the majority of patients afflicted by it require therapy. The most common reason to initiate treatment is neutropenia with or without associated infectious complications, or the development of severe thrombocytopenia. Therapeutic options in hairy cell leukaemia include splenectomy, interferon administration, or the use of chemotherapeutic agents such as pentostatin (2'-deoxycoformycin) and 2-chlorodeoxyadenosine. Splenectomy is still indicated in the treatment of young patients with significant splenomegaly and only minimal bone marrow involvement. Interferon treatment induces remission in approximately 90% of patients with hairy cell leukaemia, but complete remission is obtained in only 5-10%. The development of antibodies against interferon was initially considered a major problem, but longer follow-up of patients who developed antibodies has shown that it is transient and does not have a significant impact on the overall response to treatment. Pentostatin induces complete remission in 60-70% of patients and partial remission in 20-40%. 2-Chlorodeoxyadenosine is a very promising drug in the treatment of this rare leukaemia, inducing long-lasting complete remission in approximately 80% of patients. While interferon does not cure the disease, it is possible that a subset of patients treated with pentostatin or 2-chlorodeoxyadenosine are cured. Longer follow-up of these patients will determine whether this is true.

Immunophenotype of hairy-cell leukemia

15 cases of HCL were studied with a panel of monoclonal antibodies against different leukocyte antigens. A B-cell phenotype different from that of B-CLL was observed (CD10-, CD19+, CD20+, CD21-, CD22+, CD37+, CD38-, FMC7+, LN1+, PCA-1+, BLy7+ and CD5-). As expected, CD11c and CD25 were positive and, in addition, a My7 and My9 positivity in varying degree was noted. 3 weeks of in vitro incubation did not significantly alter the phenotype. We conclude that HCL exhibits a unique phenotype among chronic B-cell leukemias, which is closer to the plasma cell stage of differentiation than that of B-CLL. The BLy7 monoclonal antibody seems to be a promising marker for HCL.

Immunological and molecular biological identification of a true case of T-hairy cell leukaemia

A hairy cell leukaemia (HCL) patient is presented in whom the peripheral blood mononuclear cells (PBMCs) carried suppressor T-cell markers (CD3+, CD2+, CD8+/CD4-, CD38+). Analysis of genomic DNA of PBMNC showed the presence of a monoclonal population of T cells, the T-cell receptor (TCR) beta-chain gene being rearranged on both alleles (DR/DR), while the immunoglobulin (Ig) heavy chain-genes were in germline configuration. The neoplastic cells were found to react with the monoclonal antibody RAB-1 - originally described as belonging to the B lineage-restricted monoclonal antibodies - and to carry RAB-1/CD-8 in a double marker assay. Natural killer activity of PBMNCs against K562 target cells was severely reduced, while the cells were found to exert strong antibody-dependent cellular cytotoxicity.

Treatment of hairy cell leukemia with increasing doses of recombinant alpha A interferon

Since July 1984, eight patients with advanced hairy cell leukemia have received treatment with recombinant alpha A interferon. At commencement of interferon, seven patients had progressive cytopenia, and one was in leukemic phase (greater than 20 x 10(9)/L circulating hairy cells). All patients had had previous splenectomy. Interferon was administered subcutaneously. The initial dose was 3 x 10(6) U/day, continued until peripheral counts stabilised. Subsequently, patients received 6 x 10(6) U/day, 9 x 10(6) U/day, and finally 12 x 10(6) U/day. The dose increases proceeded every 8-12 weeks, as tolerated. Seven patients had an objective response. There were four complete remissions, two partial remissions, and one minor response. Complete remission was documented only in patients on at least 6 x 10(6) U/day for 12 weeks. The median time to complete remission was 40 weeks (range 35-53). Normalisation of peripheral blood counts preceded histologic marrow improvement. The median times for response (platelets greater than or equal to 100 x 10(9)/L, hemaglobin greater than or equal to 12 gm/dL, neutrophils greater than or equal to 1.5 x 10(9)/L), were six to eight and 17 weeks, respectively. Toxicity included myelosuppression during the first four weeks of therapy. With increasing doses of interferon, myelosuppression did not recur. A transient, mild, flu-like syndrome affected all patients. Two patients developed asymptomatic transaminitis at doses greater than 6 X 10(6) U/day. This resolved with dose reduction. In one case impotence was reported during the first four weeks of each interferon level.(ABSTRACT TRUNCATED AT 250 WORDS)

Hairy cell leukemia cells express CD1a antigen

Five patients with hairy cell leukemia (HCL) were studied. Peripheral blood leukocytes, rosette-forming cells (T) and non-T-cells were stained in immunofluorescence by a panel of monoclonal antibodies to investigate the phenotype of HCL cells (HCLC). In all patients HCLC showed B-lymphocyte phenotype, although they were not stained by antibodies reactive for monocytes, natural killer cells, or T-cells. However, in all instances the large majority of HCLC were unexpectedly stained with an antibody (anti-CD1a) usually detectable only in early thymocytes and on Langerhans cells. This finding was further confirmed by immunoelectron microscopy. This type of ambiguity in the lineage of HCL could imply that HCLC might arise from cells differentiated towards the B-cell lineage, still sustaining an early antigen of a different (T) lineage. These results, moreover, extend the range of the known distribution of the CD1a antigen, which could be useful in diagnosing HCL.

Hairy cell leukemia: clinical features and therapeutic advances

Hairy cell leukemia (HCL) is a rare chronic lymphoproliferative disorder which has been extensively studied over the past decade. Much has been learned regarding the diagnosis, natural history, biology, and treatment of this unique neoplasm. The disease most commonly affects middle aged men and characteristic clinical features include splenomegaly, cytopenias, and usually the presence in the peripheral blood of distinctive 'hairy cells' with irregular cytoplasmic projections. Diagnosis can usually be confirmed by bone marrow biopsy. Although the natural history can be extremely variable among patients, complications are usually referable to the cytopenias, with anemia and infection being most frequent. In addition to pyogenic infections, patients are susceptible to unusual organisms including atypical mycobacterium, legionella, and fungi. The requirement of red blood cell transfusion, severe granulocytopenia or thrombocytopenia, frequent infections, or painful splenomegaly are all indications for treatment. Splenectomy is the standard initial treatment of choice. However, in the past few years there have been exciting major advances in the therapeutic modalities for HCL. Recombinant alpha-interferon is highly effective, with beneficial responses occurring in close to 90% of patients. The Food and Drug Administration has recently approved the use of interferon for HCL. This represents the first time a biological response modifier has been approved for the treatment of human disease. In addition, preliminary results with the adenosine deaminase inhibitor, 2'deoxycoformycin (dcf), have been encouraging. Further clinical trials are required in order to determine the optimal sequential treatment strategy for HCL. The exact mechanisms of action of both interferon and dcf in HCL remain to be elucidated. A better understanding of the unusual features of the hairy cell and the underlying biological effect of these two agents in HCL may have important applications in other hematologic and non-hematologic malignancies.

[Low-dose alpha-interferon treatment of hairy cell leukemia]

Fifteen patients (36-71 years old) with histologically proven hairy-cell leukemia were treated with a low dose of IFN-alpha. The treatment consisted of 1 million I.U. given daily subcutaneously. After 1 month the dose was reduced in all patients 1 million I.U. thrice weekly. Four of the 15 patients have been splenectomized, with two patients receiving chemotherapy prior to the IFN treatment. All patients exhibited at least one cytopenia. The IFN treatment was well tolerated. Only two of the 15 patients experienced mild fever after the first injection, one patient had apathia and mild somnolence after 2 months of therapy. At present 15 patients can be evaluated: 6-18 months after start of therapy two patients showed a complete response with normalization of both peripheral blood and bone marrow, 10 patients experienced a partial response, while one patient showed a slight response with improvement of the thrombocyte count only. Two patients showed no improvement after 3 months of therapy; these patients are presently being treated with 5 million I.U. IFN-alpha thrice weekly. In spite of the low number of patients these data strongly indicate that IFN-alpha-2 is effective in hairy-cell leukemia at this low dose.

Hairy cell leukemia

Hairy cell leukemia is a chronic lymphoproliferative disorder that has been recognized as a separate clinical pathologic entity for the last 25 years. After a decade of discussions about the origin of the neoplastic cell, it has now been well established that hairy cells represent a certain, rather mature stage of B-cell differentiation. Evidence for this has been derived from studies using immunophenotyping with monoclonal and polyclonal antibodies, cytochemistry, and immunoglobulin gene rearrangement. For many years, splenectomy was the only therapy of proven value in hairy cell leukemia. For patients who showed insufficient response to the operation, chemotherapy with low-dose alkylating agents was moderately successful, whereas polychemotherapy often resulted in excessive toxicity. More recently, therapy with alpha-interferon has been shown to be very promising, whereas deoxycoformicin may be an attractive alternative. These new advances in immunology and therapy are reviewed.

Hairy cell leukemia

Hairy cell leukemia is a malignancy with a variable course that can be relatively indolent or rapidly fatal. Alterations in the immune system are responsible for much of the morbidity and mortality from hairy cell leukemia. More than 60% of patients die from infection, and infections are both pyogenic and nonpyogenic. Many patients have transfusion requirements, and bleeding complications can also occur. Treatment strategies for hairy cell leukemia have evolved and are being modified as more is learned about the disease. Splenectomy is the initial treatment when patients become symptomatic, and if the disease progresses after splenectomy, chlorambucil offers good control in many patients. Radiation can be used for local palliation, as when complications such as bulky adenopathy or bone lesions occur. Initial studies using interferon in the treatment of hairy cell leukemia look encouraging, but more investigation is necessary before the role of interferon in treatment of hairy cell leukemia is determined.

Immunoglobulin synthesis in hairy cell leukaemia. Ultrastructural immunocytochemical study of 3 cases

3 cases of hairy cell leukaemia were studied with ultrastructural immunocytochemical methods using an anti human Ig HRPO-Fab fragment. Ig were detected on the cell surface, in the perinuclear cisterna and endoplasmic reticulum of hairy cells. Evidence of Ig in these sites demonstrates a B-lymphoid differentiation of the leukaemic cells.

Phenotypic changes of phytohaemagglutinin-stimulated hairy cells

Hairy cell leukaemia (leukaemic reticuloendotheliosis) appears to be a homogeneous and well defined disease on the basis of clinical presentation, light and electron microscopic features and cytochemical characteristics, but the study of immunological markers of hairy cells (HC) from many patients reveals apparent heterogeneity. The most common phenotype associates B-cell and monocytic properties: HC usually express monoclonal surface (and in certain cases cytoplasmic) immunoglobulins, receptors for IgM and IgG Fc, and mouse erythrocytes, and la-like antigens. Additionally, they are capable of phagocytosis, glass adherence, lysozyme and peroxidase synthesis. However, most of these features are not constant and cases have been reported in which HC fail to express one or more of these properties. In certain cases HC even display a T-cell phenotype, while, in others, features of both T and B cells are expressed. Moreover, in two recently studied patients, the phenotype of HC in the blood differed from that in the spleen (B + T in the blood and B in the spleen). These surprising discrepancies led us to hypothesize that HC from the same individual might be able to express different phenotypes following an appropriate stimulus. We therefore studied immunological parameters of HC stimulated by mitogens and the results indeed showed that after stimulation by phytohaemagglutinin (PHA) the cells switched from B to T or B + T phenotypes.