T gamma (T gamma) cells suppress growth of erythroid colony-forming units in vitro in the pure red cell aplasia of B-cell chronic lymphocytic leukemia

Splenic irradiation in chronic lymphocytic leukemia. A 10-year experience at a single institution

A group of 38 patients with a median age of 70 years and chronic lymphocytic leukemia (CLL) were treated using a cobalt 60 U or a 6-MeV linear accelerator. A direct field or two opposite fields covered the palpable spleen area in most patients. 100 cGy were administered weekly for a total dose of 10 Gy, given over 10 weeks. The stage arrangement (according to Rai) for the 32 evaluable patients was as follows: Stage I: 11 patients, Stage II: nine patients, Stage III: three patients, and Stage IV: nine patients. Patients in Stages I and II were treated when symptomatic. Twenty-five patients (78%) achieved hematologic response (HR), defined as normalization of the differential leukocyte count, of the total blood cell count, and of bone marrow infiltration. However, no complete response according to the standard criteria of response has been obtained. The median response time of HR was 7 months (range, 1.5 months to greater than 120 months). The overall median survival time from the start of splenic irradiation (SI) was 40 months. More than 50% splenomegaly reduction was obtained in 63% of patients, whereas no benefit was verified in the lymphadenopathy. The incidence of second tumor was 29%. Fourteen patients benefited from a further 21 SI cycles. SI does not result in a complete remission and therefore cannot modify the course of CLL. This treatment is most advisable for elderly patients with predominant bone marrow lymphocytosis, for patients with previous extensive chemotherapy or radiotherapy, and for patients with poor marrow reserve. Moreover, because of the absence of toxicity subsequent treatment is not compromised.

Chronic T cell lymphoproliferative disorder and pure red cell aplasia. Further characterization of cell-mediated inhibition of erythropoiesis and clinical response to cytotoxic chemotherapy

Two patients with pure red cell aplasia and a T cell lymphoproliferative disorder were studied in order to define the mechanism of suppression of erythropoiesis and the patients' response to cytotoxic therapy. In vitro assays demonstrated enhanced formation of both erythroid colonies and bursts following T-cell depletion. Erythroid colony formation was suppressed by the readdition of autologous T cells to a null cell fraction of marrow mononuclear cells. Media conditioned by the patients' T cells did not exhibit any inhibitory effect on erythroid colony formation by autologous T cell-depleted marrow cells. These in vitro results suggested that T cell-mediated suppression of erythropoiesis was responsible for the generation of pure red cell aplasia. In both patients, cyclophosphamide therapy resulted in clinical remissions manifested by normalization of the hematocrits associated with a reduction in circulating lymphocytes from more than 10,000/mm3 to under 500/mm3. Maintenance chemotherapy has caused persistent inhibition of lymphocyte counts along with durable remissions with normal hematocrits.

Cyclosporin-A for the treatment of pure red cell aplasia in a patient with chronic lymphocytic leukemia

A 62-year-old man with B-cell chronic lymphocytic leukemia had three separate episodes of pure red cell aplasia (PRCA). The last episode was treated with cyclosporin-A (CyA) and prednisone. After the patient was on the therapy for 2 weeks, erythropoietic recovery was observed and with continued therapy the hematocrit (Hct) became normal. The PRCA remission was associated with a fall in the blood lymphocyte count, and a reduction in the spleen and lymph node size and bone marrow lymphocyte density. At diagnosis of PRCA the blood T-cells bearing IgG Fc receptors (T gamma cells) were increased, and the marrow contained very few or no late-stage erythroid progenitors. After remission of PRCA the T gamma cell fraction decreased, and the marrow erythroid progenitor's number became normal. We speculate that therapy with CyA and prednisone inhibited the production of interleukins-1 and -2 from monocytes and T-cells, respectively, and was responsible for the reduction of the T gamma cell fraction and B-cell leukemic mass in this patient. Further, we believe that normalization of T gamma cells in association with the therapy was responsible for the PRCA remission.

Role of natural killer (NK) cells in the production of the murine T lymphocyte allorecognition repertoire

Limiting dilution cultures of alloreactive (anti-H2Kb) CTL were established from thymocyte or spleen cell pools of C3H/HeJ and their congenic bg/bg partner, or of SJL/J and their congenic bg/bg partner. CTL populations in these cultures were assayed for cross-reactive lysis of a panel of splenic Con A blasts of H2Kbm mutant mice. There was some slight elevation of frequency of CTLp in the thymocyte lymphoid pool of bg/bg mice; more strikingly, the repertoire of anti-H2Kb specificities was clearly altered in both strains in the bg/bg animals. There was apparently an increased diversity (more specificities represented at higher frequencies) in the thymocyte pool and a decreased diversity in the spleen cell CTLp pool in animals with the bg/bg marker. Similar shifts in the allorecognition repertoire of normal C3H/HeJ mice were produced by inoculation of neonatal mice with a rabbit anti-NK heteroantibody (antiasialo GM1). Preabsorption of this serum such that it lost anti-NK activity also abolished this effect of in vivo neonatal injection. Furthermore, injection of bg/bg bone marrow-reconstituted C3H/HeJ (bg/+) mice with a C3H spleen cell-derived NK line also caused a shift in the allorecognition repertoire toward that seen in the normal littermate control animals.

Transient response of pure red cell aplasia to anti-thymocyte globulin in a patient with T-cell chronic lymphocytic leukemia

Pure red cell aplasia (PRCA) is an unusual complication of chronic lymphoproliferative disorders. A patient with T-cell chronic lymphocytic leukemia (T-CLL) had severe anemia and neutropenia. Initial in vitro studies demonstrated no evidence of T-cell suppression of erythropoiesis. Sequential bone marrow examinations demonstrated progressive red cell aplasia. In vitro studies showed that the T-cells from the patient suppressed allogeneic but not autologous BFU-E. Treatment with antithymocyte globulin (ATG) reduced circulating leukemic cells and produced a definite but transient improvement in erythropoiesis.

Regulation of hematopoiesis by T lymphocytes and natural killer cells

T lymphocytes and natural killer (NK) cells exert both stimulatory and suppressive effects that regulate growth and differentiation of hematopoietic cells. Activated T and NK cells have been demonstrated in different pathological states of bone marrow failure and are proposed to play a role in the pathogenesis of the disease. T and NK cells have also been shown to be responsible for bone marrow graft rejection in both allogeneic and syngeneic donor/recipient combinations. Lymphocytes can regulate hematopoietic cell growth by direct cellular contact or by releasing soluble factors, such as colony-stimulating factors, immune interferon, lymphotoxin, and tumor necrosis factor, active on hematopoietic precursor cells.

Neutropenia associated with large granular lymphocytes responsive to corticosteroids in vitro and in vivo

We describe a patient with neutropenia associated with increased circulating large granular lymphocytes (LGL). Absolute neutropenia was accompanied by the absence of myeloid precursor cells in the bone marrow. No myeloid progenitor cells (CFU-C) could be detected by in vitro colony culture. The peripheral blood was also remarkable for the presence of a population of large granular lymphocytes demonstrable by conventional staining. These cells in flow microfluorometry studies expressed antigens Leu 4 (T-cell antigen receptor), Leu 7 (natural killer cell marker), Leu 2 (suppressor cell marker), and HLA-DR (activation marker); they lacked Leu 1 (a pan-T cell antigen), Leu 3 (helper cell marker) and Tac (interleukin 2 receptor). Hematopoietic colony formation in vitro improved with addition of corticosteroids to the culture medium or elimination of the LGL population with complement-mediated cytotoxicity. Anti-neutrophil antibodies were present prior to and following therapy. Clinically, administration of prednisone resulted in a normalization of the total white blood cell count and absolute polymorphonuclear cell number, an increase into the normal range of the number of CFU-C, and elimination of the LGL population. In this case of steroid-responsive LGL-associated neutropenia, laboratory studies suggested direct suppression of myelopoiesis by steroid-responsive LGL.

Pure red cell aplasia: response to therapy with anti-thymocyte globulin

Pure red cell aplasia (PRCA) results from the failure of erythrocyte differentiation and may respond to immunosuppressive therapies. We have treated nine patients with PRCA refractory to steroids and/or cyclophosphamide with anti-thymocyte globulin (ATG). Six patients had normal numbers of erythroid bursts (from erythroid burst-forming units) or erythroid colonies (from erythroid colony-forming units) detectable in vitro, and all responded to therapy with ATG. In vitro studies suggested T-cell inhibition of erythropoiesis in four of these six patients and humorally mediated erythroid suppression in one. In three individuals, virtually no erythroid progenitors were detected in marrow culture. None of these patients responded to ATG. Myelofibrosis, 5q- chromosomal abnormality, or the subsequent development of thrombocytopenia in these individuals suggested that PRCA resulted from an intrinsic stem cell disorder. Our studies demonstrate that ATG is effective therapy for PRCA, and it may be especially useful in children or other patients in whom alkylating agents are not appropriate. We also confirm that erythroid growth in marrow culture predicts those patients who will respond to ATG or other immunosuppressive therapies.

T-cell chronic lymphocytic leukemia with pure red cell aplasia: laboratory demonstration of persistent leukemia in spite of apparent complete clinical remission

A 40-year-old woman presented with splenomegaly, macrocytic anemia, and red cell aplasia. Although lymphocytosis was absent in the peripheral blood, large atypical lymphoid aggregates were present in the bone marrow. Splenectomy resulted in partial remission of red cell aplasia, but a gradual increase in the number of peripheral blood lymphocytes followed during the next 36 months. Flow cytometric analysis demonstrated that the majority of these peripheral blood lymphocytes had suppressor, natural killer T-cell phenotype. No other treatment was given until red cell hypoplasia worsened 42 months after initial presentation. Repeat bone marrow evaluation again demonstrated severe erythroid hypoplasia and large abnormal lymphocytic infiltrates. Cyclophosphamide given for 8 months resulted in complete resolution of the red cell aplasia and complete clinical remission of CLL. However, flow cytometric analysis revealed persistent increase in bone marrow T-cells, and bone marrow co-culture studies demonstrated residual ability of peripheral blood mononuclear cells to inhibit erythropoiesis in vitro, suggesting that residual, clinically undetectable leukemia persists in spite of complete clinical remission.

Pure red cell aplasia: lymphocyte inhibition of erythropoiesis

The pathogenesis of pure red cell aplasia (PRCA) was studied in a patient who had no evidence of malignancy. In marrow culture, no erythroid colonies (from late erythroid progenitors [CFU-E]) but normal numbers of well-haemoglobinized erythroid bursts (from early erythroid progenitors [BFU-E]) were found, indicating that BFU-E existed in the patient but that their subsequent in vivo differentiation was inhibited. Autologous coculture studies suggested that inhibition was mediated by the patient's ER + lymphocytes. After remission was induced with cyclophosphamide, autologous ER + cells no longer suppressed in vitro erythropoiesis. However, cryopreserved ER + cells, obtained with anaemia, suppressed BFU-E growth from remission marrow. An expanded population of large granular lymphocytes (LGL) with ER +, Fc gamma +, T3+, T8+, HNK-1+, Ia-, M1 -- phenotype and no functional natural killer (NK) cell activity was noted during PRCA that reverted to normal with remission. For this patient, both in vivo and in vitro evidence demonstrates a cellular inhibition of erythropoiesis at the level of differentiation between BFU-E and CFU-E.

Hematologic and cytogenetic remission of 5q-refractory anemia after syngeneic bone marrow transplantation

Refractory macrocytic anemia with hypolobulated megakaryocytic nuclei and partial deletion of the long arm of chromosome 5 has been termed the 5q- syndrome. Although long survival has been reported in a few cases of 5q- refractory anemia, accumulating evidence suggests that this syndrome is a preleukemic state with risk of transformation to acute nonlymphocytic leukemia as well as complications of bone marrow failure. This report describes the first apparently successful therapy for this disorder in a young man who originally presented with a clinical picture consistent with pure red cell aplasia and normal marrow chromosomes but with hypolobulated megakaryocytic nuclei. He was treated with vitamins, androgens, and sequential trials of immunosuppressive therapy, all without response. Two years after diagnosis, repeated marrow cytogenetic studies showed a 5q- abnormality in 70 percent and later in 100 percent of marrow metaphases. Because of transfusion-induced hemosiderosis and the availability of a cytogenetically normal monozygotic twin, bone marrow transplantation was undertaken. In light of the clonal (and suspected preleukemic) nature of the 5q- syndrome, the patient's marrow was ablated with a busulfan plus cyclophosphamide regimen used for patients with nonlymphocytic leukemia. Sustained engraftment of cytogenetically normal marrow ensued. Two years after transplantation, and following six months of regular phlebotomy, the patient was hematologically normal with a normal serum ferritin level.

'Supernatural' killer cells

The observation that lymphocytes from healthy individuals, without any known sensitization, could spontaneously lyse tumour target cells in vitro(1,2) was first thought to be an in-vitro artefact. Now the effector cells, known as natural killer (NK) cells, are accepted as a clearly distinct albeit heterogeneous subpopulation of lymphocytes. Yet their lineage remains controversial and despite much interest in the role of NK cells in protection against infection and cancer, their biological significance is far fiom clear(3-5). In this article Gordon Burns and his colleagues discuss recent research on NK cells which has illuminated the diverse effects of lymphokines, expanded knowledge on the mechanisms of cell recognition and killing by cytotoxic effector cells, and illustrated how a variety of leukocytes mediate more than one function - results of general interest to cell biologists.

Functional properties of a unique subset of cytotoxic CD3+ T lymphocytes that express Fc receptors for IgG (CD16/Leu-11 antigen)

A subset of peripheral blood T lymphocytes coexpressing CD3 and IgG Fc receptors (FcR) (CD16/Leu-11 antigen) have been identified, isolated, and functionally characterized. The CD3+, CD16+ cells were established in short-term culture using growth medium containing interleukin 2 (IL-2). Both the freshly isolated cells and the cultured cell line stably expressed the CD3+, CD16+ phenotype. Furthermore, a majority of these T cells lacked either CD4 or CD8 expression. Like in vitro-activated cytotoxic T lymphocytes and natural killer (NK) cells, the CD3+, CD16+ cells showed numerous azurophilic granules. Although these cells failed to mediate significant levels of NK cell-mediated cytotoxicity even after stimulation with IL-2, they efficiently functioned as effectors of antibody-dependent cellular cytotoxicity (ADCC). The Ig isotype specificity of the ADCC was analyzed using an isotype switch-variant family of a murine anti-HLA monoclonal antibody (mAb). Similar to the CD3-, CD16+ NK cell population, the CD3+, CD16+ T cells preferentially used the IgG2a antibody to mediate ADCC. The CD3+, CD16+ cells demonstrated a proliferative response when cocultured with either a NK-sensitive tumor cell line, K562, or a NK-insensitive B lymphoblastoid cell line, CCRF-SB. The response against CCRF-SB was significantly inhibited by anti-IL-2 receptor antibody, whereas the response against K562 was only partially diminished. Cytotoxicity was also induced in the CD3+, CD16+ population by the presence of anti-CD3 mAb, indicating that cytotoxicity can be triggered by stimulation via the CD3-T cell antigen receptor complex. By isolating these CD3+, CD16+ cells from the peripheral blood of a normal, healthy individual, it has been possible to extensively study the morphology, antigenic phenotype, and functional behavior of this unique subset of T lymphocytes expressing IgG FcR.

The possible role of radiotherapy in chronic lymphocytic leukaemia: a critical review

The few clinical studies which have utilized irradiation as a treatment modality for chronic lymphocytic leukaemia (CLL) during the last two decades have led to rather conflicting and sometimes disappointing results. Low-dose total body irradiation (TBI) and extracorporeal, or mediastinal, radiotherapy did not appear to be superior to chemotherapy in most trials. Only the fractionated low-dose (600-800 rad) splenic irradiation was found to induce a long-lasting decrease of the lymphocyte count and a decrease in bone marrow infiltration in a significant proportion of cases, without any noticeable haematological toxicity. But new data is recently emerging; stratification of CLL in various subgroups, better understanding of the role of the normal T-cell subsets, better knowledge of the interaction between irradiation and haematopoiesis, and of the radiosensitivity of the various lymphocyte subpopulations. Thus one can now reconsider the possible role radiotherapy, and particularly splenic irradiation, can play as an alternative treatment to chemotherapy for CLL. Haematological toxicity is still limiting the use of TBI. The spleen irradiation avoids this drawback. Recent data suggest that this splenic irradiation could be efficient by means of several mechanisms; the successive destruction, fraction after fraction, of the part of the malignant lymphocyte clone present in the spleen is likely to be the main therapeutic explanation, with the knowledge that the lower the differentiation of the malignant clone, the more efficacious the irradiation. But in parallel, the destruction of the large subset of T-suppressors which is constantly present in the spleen may account for the improvement of the peripheral blood count after splenic irradiation, and possibly for a direct effect towards the malignant clone. With respect to these new data, splenic irradiation clearly needs further clinical evaluation in the treatment of CLL.

Interferon-induced aplasia: evidence for T-cell-mediated suppression of hematopoiesis and recovery after treatment with horse antihuman thymocyte globulin

A severe and persistent pancytopenia occurred in a 42-year-old woman with a non-Hodgkin's lymphoma following a 10-day course of intramuscular human leukocyte alpha interferon (IFN, 9.0 IU/day). Within 2 weeks of IFN, marrow nucleated myeloid and erythroid precursor cells and megakaryocytes were nearly absent and marrow progenitor cells (CFU-E, BFU-E, CFU-GM) were undetectable. Analysis of marrow lymphocytes revealed that nearly 50% of the cells were E-rosette+, T gamma+, OKT8+ (suppressor/cytotoxic) T-and/or Leu 7+ natural killer (NK) lymphocytes and 50% were IgM Kappa, B1+, B-lymphocytes. In vitro erythroid culture studies were consistent with T-cell-mediated suppression of erythropoiesis. After 2 months without improvement on corticosteroid/androgen therapy, a 10-day course of intravenous antithymocyte globulin (ATG) was administered. This was followed by a prompt reticulocytosis and a rise in blood neutrophils. After ATG therapy, there was a sixfold reduction in marrow suppressor cells, loss of in vitro suppressor effects on erythroid progenitor cells, and complete reversal of blood and marrow OKT4/OKT8 (helper/suppressor) ratios. These studies suggest that interferon may suppress hematopoiesis in some patients by activating marrow suppressor T- and/or NK cells. Treatment aimed at reduction of marrow suppressor cells may aid in hematologic recovery without eliminating the infiltrating lymphoma.

Inhibition of bone marrow colony formation by human natural killer cells and by natural killer cell-derived colony-inhibiting activity

Incubation of human peripheral blood lymphocytes with bone marrow cells resulted in significant inhibition of colony formation by committed myeloid and erythroid cells. Using positively selected homogeneous natural killer (NK) cell preparations and lymphocyte subpopulations depleted of or enriched for NK cells, we definitively characterize as NK cells the cells in normal peripheral blood that are responsible for inhibition of bone marrow colony growth. The inhibitory effect of NK cells on hematopoiesis can be mediated by a soluble factor that is produced only by NK cells upon culture with HLA-DR+ hematopoietic cells and with NK-sensitive cell lines. Both NK cells and the NK-produced, colony-inhibiting activity (NK-CIA) are suppressive for allogeneic and autologous bone marrow CFU-GEMM (colony-forming units, granulocyte, erythroid, monocyte, megakaryocyte), CFU-E (CFU, erythroid), and early CFU-GM (CFU, granulocyte, monocyte), but not for either BFU-E (burst-forming units, erythroid) or late CFU-GM. [3H]Thymidine incorporation was inhibited by NK-CIA-containing supernatants in HLA-DR+ but not HLA-DR- bone marrow cell populations stimulated to proliferative by colony-stimulating factor (CSF). These data suggest that the NK cell-mediated inhibitory effect on proliferation and differentiation of hematopoietic precursor cells is mediated in part or completely by the secreted NK-CIA. The concentration of NK-CIA reached in the supernatant of the mixture of NK cell-containing lymphocyte populations with bone marrow cells is sufficient to account for the inhibitory effect mediated by NK cells. Our data support the hypothesis that human NK cells play a major role in the control of hematopoiesis, down-regulating it under conditions in which the NK cells are functionally activated.

Large granular lymphocyte (LGL) lymphoproliferative diseases: naturally cytotoxic tumors in man and experimental animals

It has recently become clear that in the spleen and blood of both rodents and man that a unique subpopulation of lymphocyte is the mediator of virtually all of the inherent natural killer (NK) and antibody-dependent cell-mediated cytotoxic (ADCC) activity. Because of their large size, eccentric kidney-shaped nucleus and prominent cytoplasmic granules, these cytotoxic cells, termed large granular lymphocytes (LGL), can be readily identified in Geimsa stained cytocentrafuge preparations. Unfortunately, the relatively low numbers of these cells in normal lymphoid tissues has made the detailed analysis of LGL quite difficult. Recently however, a number of investigators have reported both rodent and human leukemias or leukocytosis in which there was an abnormally high number of circulating lymphocytes with either the appearance and/or function of LGL. The present manuscript reviews this literature with an emphasis on the biological and clinical characteristics of this lymphoproliferative disease. Emphasis is also placed on the usefulness of these cells for the detailed analysis of LGL morphology and function.

Anemia in cancer

In summary, anemia developing in a patient with cancer can be due to several different factors. A relative failure of erythropoiesis, in conjunction with a modestly shortened erythrocyte survival, is the most likely explanation for the anemia and can occur in patients with or without bone marrow invasion. Several theories have been proposed to explain the mechanism of limited red cell production in cancer. Internal iron starvation and cancer toxic factors have been widely implicated. Immunoglobulin inhibitors of erythropoiesis occur in the rare entity, pure red cell aplasia, which is sometimes associated with thymomas. Autoimmune hemolytic anemia and microangiopathic hemolytic anemia can also occur in patients with solid cancers, pointing out the need for a complete evaluation of anemia in any patient with recent-onset anemia. Successful treatment and prognostic implications of anemia in cancer is dependent on proper diagnosis.

Successful treatment of chronic refractory pure red cell aplasia with antithymocyte globulin: correlation with in vitro erythroid culture studies

Two contrasting cases of chronic refractory pure red cell aplasia (PRCA) responsive to a commercial preparation of horse antihuman thymocyte globulin (ATG) are reported. Both cases were refractory to trials of cyclophosphamide, corticosteroids, and plasmapheresis. One patient developed a reticulocytosis after a single intravenous infusion of ATG; the other patient responded after administration of 14.7 g of ATG over a 28-day course. At presentation, erythroid progenitors (CFU-E and BFU-E) in one patient were normal; in the second patient, the number of erythroid progenitors was severely reduced. Neither patient had a serum IgG inhibitor to progenitor cells as judged by in vitro erythroid colony studies. Both patients had increased numbers of marrow T-cells and co-culture studies in one case were consistent with T-cell-mediated suppression of erythropoiesis. These studies confirm that ATG is a useful agent in the treatment of refractory PRCA. However, ATG may not act by removal of T suppressor cells in all cases.

Pure red cell aplasia: relationship between inhibitory activity of T cells to CFU-E and erythropoiesis

T cell-mediated inhibition of autologous late erythroid colony formation was found in two patients with PRCA. Each patient was treated separately with immunosuppressive agents, ALG, bolus methylprednisolone or cyclophosphamide. Cyclophosphamide was the most effective among these immunosuppressive therapies. Peripheral blood T cells, which were taken serially from the patients during the course of the disease, were cryopreserved until use. The inhibitory activity of T cells was assayed after remission using autologous bone marrow. It was found that the decrease of inhibitory activity was closely correlated with clinical improvement and that the effectiveness of the immunosuppressive therapy on inhibitory activities of T cells differed between therapies. These findings suggest that T cell-mediated inhibition of erythropoiesis may be pathogenetic for PRCA in some patients.

Pathology-important advances in clinical medicine: assessing fetal lung maturity

The Scientific Board of the California Medical Association presents the following inventory of items of progress in pathology. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, research workers or scholars to stay abreast of these items of progress in pathology that have recently achieved a substantial degree of authoritative acceptance, whether in their own field of special interest or another.The items of progress listed below were selected by the Advisory Panel to the Section on Pathology of the California Medical Association and the summaries were prepared under its direction.

Chronic lymphocytic leukemia

This article reviews, for the internist, recent advances in our understanding of the immunology and clinical characteristics of chronic lymphocytic leukemia (CLL). The method of treatment based on clinical staging of CLL and as practiced in the authors' clinic is detailed. It also provides an outline of possible investigation and therapy that may be expected in the coming years.

Evidence for genetic restriction in the suppression of erythropoiesis by a unique subset of T lymphocytes in man

The suppression of erythropoiesis by lymphocytes from patients with a T cell lymphoproliferative syndrome and pure erythrocyte aplasia has been previously demonstrated. To study the nature of the suppressor cell and possible genetic restriction of this suppression, we investigated a patient with severe anemia, splenomegaly, lymphocytosis, and erythroid aplasia. A 3-mo course of low-dose daily oral cyclophosphamide achieved a complete remission for over 12 mo. The surface phenotype of his lymphocytes was analyzed by means of antibodies to lineage, differentiation, and activation-specific surface antigens. The cells expressed mature T cell antigens T3, T8, and T11, while lacking T1. Immature T cell, B cell, and the monocyte-specific antigen Mo2 were absent, while Mo1, a monocyte-associated antigen not normally expressed on T cells, was present. T10 and Ia expressed as activation antigens were also present. The cells, cryopreserved at diagnosis, were thawed and co-cultured in plasma clot with patient remission marrow samples at T cell/bone marrow ratios of 1:1 and 2:1. There was nearly 90% suppression of erythroid colony-forming unit expression and 60% suppression of erythroid burst-forming unit expression at 2:1 T cell to bone marrow ratios and somewhat less suppression at 1:1. Granulocyte/macrophage progenitor expression was unaffected. Erythroid progenitor differentiation in the marrows of two HLA identical siblings was similarly suppressed. The cells were co-cultured with the marrows of nine nonrelated donors to investigate the potential genetic restriction of this suppression. Colony suppression equal to that observed in the marrow of the patient and his siblings was found in studies of two partially HLA identical individuals. No suppression was detected in marrow co-cultures of two entirely HLA dissimilar individuals. These results show that suppression of erythropoiesis by a unique subset of T8, Mo1, Ia-positive lymphocytes isolated from a patient with lymphocytosis and erythrocyte aplasia is genetically restricted.

Acquired pure red cell aplasia associated with chronic lymphocytic leukemia

Pure red cell aplasia (PRCA) represents selective failure of erythropoiesis in the absence of abnormalities in leukopoiesis or thrombocytopoiesis. Acquired PRCA has occurred uncommonly in chronic lymphocytic leukemia (CLL). We report six patients with non-T-cell CLL in which nine episodes of PRCA were observed. In six of the nine episodes, the patients had received recent oral alkylating agents; conversely, recovery from aplasia occurred in some while on alternate alkylator therapy and two patients had no pretreatment. Spontaneous occurrence and recovery, therefore, could not be excluded. Onset of PRCA may be suggested by macrocytosis, but discontinuance of therapy at its development may not prevent PRCA if, indeed, therapy is one of the causes. Supportive therapy or alkylators and prednisone permitted recovery without mortality in all six patients. The interval between onset of CLL and the recognition of first PRCA episode varied from one month to nine years (mean, 5.3 years); the duration of PRCA ranged from three to nine months (mean, 4.7 months). In addition to previously better understood causes of anemia in CLL, the uncommon occurrence of PRCA is an additional consideration in the differential diagnosis of sudden anemia in CLL.