Acquired pure red cell aplasia

Pure red cell aplasia secondary to rheumatoid arthritis: a case report

BACKGROUND

Rheumatoid arthritis is a common autoimmune disease with many extra-articular manifestations. Pure red cell aplasia is a rare manifestation of rheumatoid arthritis and is sparsely documented in the literature, with a variable clinical outcome following immunosuppressive therapy.

CASE PRESENTATION

A 63-year-old Sinhalese female presented with transfusion-dependent anemia associated with deforming inflammatory arthritis. She also had leukopenia, right subclavian venous thrombosis, and generalized lymphadenopathy. The diagnosis of rheumatoid arthritis following initial clinical workup and additional blood and bone marrow investigations revealed pure red cell aplasia as a secondary manifestation of rheumatoid arthritis after excluding other secondary causes, such as infections, thymoma, thrombophilic conditions, and hematological malignancy. She responded well to oral prednisolone, cyclosporine A, and hydroxychloroquine, and she attained complete recovery in 2 months.

CONCLUSION

Pure red cell aplasia is a disabling illness that may lead to transfusion-dependent anemia, which may occur due to rare extrapulmonary manifestation of rheumatoid arthritis. The diagnosis of pure red cell aplasia secondary to rheumatoid arthritis may be challenging where hematological investigations, including bone marrow biopsy, will aid in the diagnosis, and early diagnosis and treatment will bring about a better outcome.

Foscarnet Therapy for Pure Red Cell Aplasia Related to Human Parvovirus B19 Infection in Kidney Transplant Recipients: A Preliminary Exploration

Background

Parvovirus B19-associated pure red cell aplasia (PVB19-PRCA) is an uncommon but serious complication after kidney transplantation. Currently, intravenous immunoglobulin (IVIG) is preferred as the first-line treatment for PVB19-PRCA, but presents with disadvantages of disease recurrence and expensive cost. In this context, we propose that foscarnet therapy for kidney transplantation recipients (KTR) with PVB19-PRCA may be an alternative scenario. No related study has been reported, and we performed this study to assess the efficacy and safety of foscarnet for PVB19-associated PRCA in KTR.

Methods

We conducted a retrospective review of PVB19-PRCA in KTR at our center over 9-year period. The data on therapy and outcomes in all cases treated with foscarnet are detailed records and summarized.

Results

Among our 68 patients, PVB19-PRCA was confirmed in 50 based on inclusion/exclusion criteria. All patients presented with refractory anemia and low reticulocyte percentage (<0.5%), the mean hemoglobin of patients was 79.8±12.6g/L at the time of PVB19-PRCA was identified. The median serum genome copy number of parvovirus B19 at diagnosis was 9.6 log₁₀ copies per milliliter. A total of 11 patients received foscarnet therapy, of 10 patients responded well to the treatment and maintained no recurrence. But 1 patient had a poor response to foscarnet therapy. Except for this patient, the mean hemoglobin level gradually increased from 68.5±9.3 g/L to 73.2±8.8 g/L, and the mean percentage of reticulocytes steadily increased from 0.1±0.0% to 7.6±2.9% after foscarnet therapy. The median serum genome copy number of parvovirus B19 decreased from 9.8 log₁₀ to 6.1 log₁₀ copies per milliliter. There was no significant difference (P=0.61, 0.60) in serum creatinine and glomerular filtration rate before and after foscarnet treatment. At the latest follow-up, the mean hemoglobin was 131.5±12.5 g/L and the hemoglobin correction occurred in all patients.

Conclusion

Foscarnet therapy doesn't seem to be worse than IVIG for PVB19-PRCA in KTR, and it can be an alternative option.

Management of thymoma associated autoimmune pure red cell aplasia: Case report and systematic review of the literature

Pure red cell aplasia (PRCA) is a rare paraneoplastic syndrome observed in 2-5 % of thymomas. Literature reports great variability in its management. Based on an illustrative clinical case, we present a systematic literature review whose main objective is to evaluate the therapeutic management of PRCA. The literature search was performed based on the PICO method in the Medline and Scopus databases. The reference clinical case concerns a 51-year-old woman with stage IVa thymoma. After initial response to chemotherapy, a locoregional progression occurred with PRCA development that responded favorably under second line chemotherapy. The patient finally died in a context of bicytopenia with febrile neutropenia. The systematic review covers 135 articles published between 1950 and 2019. Thymectomy alone or in combination with other therapies showed a 31 % complete remission (CR) rate for PRCA of, whereas none was reported with anti-tumor treatments without thymectomy. Among immunomodulatory therapies, cyclosporin gave the highest percentage of CR (74 %). Finally, the combination of thymectomy and immunomodulatory treatments showed a CR rate of 45 %. Thymectomy appeared to be the most effective anti-tumor treatment for PRCA. Immunomodulatory therapies, particularly cyclosporine, are shown effective, but the risk of infectious complications must be considered. The optimal place of anti-tumor and immunomodulatory therapies against PRCA has yet to be determined.

Thymoma associated with pure red cell aplasia: a case report and literature review

Pure red cell aplasia (PRCA) is a rare hematological complication associated with thymoma. Remission of PRCA occurs after thymectomy but can reappear after a latency period even without recurrence of thymoma. We report a case and we have reviewed the literature of thymoma associated with PRCA. Because of less number of reported cases, there have been no clinical trials investigating the immunosuppression regimen following thymectomy for thymoma associated with PRCA. After reviewing the literature, we came to a conclusion that thymectomy followed by immumosuppression with the cyclosporin-containing regimen is currently the most effective treatment.

Human parvovirus B19 infection induced pure red cell aplasia in liver transplant recipients

AIM

Th aim of this study was to explore the diagnosis and treatment of pure red cell aplasia (PRCA) induced by human parvovirus B19 (HPV B19) infection in liver transplant recipients.

METHODS

We described and analysed the clinical manifestation, diagnosis, treatment and prognosis of the 13 liver transplant recipients confirmed to have PRCA induced by HPV B19.

RESULTS

In the past 3 years, 13 liver transplant recipients out of a cohort of 570 recipients were confirmed to have PRCA induced by HPV B19. Some experienced fever (eight patients) but all of the patients had a gradual decline of haemoglobin levels within 2 months posttransplantation. The diagnosis was confirmed by several tests including bone marrow aspiration and polymerase chain reaction (PCR) assays. All recipients achieved remission using symptomatic treatment that included intravenous immunoglobulins (IVIG), immunosuppressive regimen switch and blood transfusion.

CONCLUSION

Pure red cell aplasia induced by HPV B19 infection is a disease with a favourable prognosis after symptomatic and supportive treatment. (i) Pure red cell aplasia anaemia is a prominent clinical sign of HPV B19 infection in liver transplant recipients. (ii) PCR technology combined with bone marrow aspiration and other laboratory examinations will meet the requirement for the diagnosis and suggests that the differential diagnosis includes PRCA and graft versus host disease (GVHD). (iii) IVIG is recommended as the first regimen for the treatment of PRCA induced by HPV B19 infection in liver transplant recipients. IVIG can be repeated if the patient has a relapse. (iv) A switch of the baseline immunosuppressive regimen may achieve a favourable curative effect.

Successful treatment of acquired pure red cell aplasia with oral corticosteroids in a patient with B-cell CLL

We present the case of a 57-year-old male patient diagnosed with chronic lymphoid leukaemia (CLL) B-cell type along with moderate anaemia. On follow-up investigations the aetiology of anaemia turned out to be pure red cell aplasia (PRCA) on trephine bone biopsy with an elevated serum erythropoietin level. The patient received blood transfusion support. He showed remarkable improvement on oral corticosteroids (prednisolone 60 mg/daily dose) with no further requirement of blood transfusion over next 3 months. However, when the dose of steroid was tapered down to 10 mg/day, the anaemia reappeared. An increase in the dose of steroid brought the haemoglobin level back to normal. Anaemia in CLL can be due to many reasons, of which PRCA is an uncommon association occurring in only around 1% of patients with CLL and usually refractory to the conventional treatment with steroids. This PRCA secondary to CLL is considered to be immune in origin and a response to combination of immunosuppressive therapy such as steroids, cyclosporine, rituximab is anticipated. Our case responded completely to oral steroids alone.

Diphenylhydantoin-induced severe yet reversible anemia during pregnancy

Diphenylhydantoin (DPH) therapy, often used in treating epileptic seizures, can cause anemia in some patients. A 26-year-old female suffered from convulsions due to encephalitis and was placed on DPH therapy. About two months after the initiation of DPH therapy, her hemoglobin level was 3.8 g/dL. Her anemia improved after the discontinuation of DPH, confirming that the anemia was caused by DPH. Pure red-cell aplasia (PRCA) combined with hemolytic anemia was indicated by results such as erythroid aplasia, an increased LDH level, and a decreased haptoglobin level. PRCA complicated by hemolytic anemia could be responsible for anemia associated with DPH.

Pure red cell aplasia and hypogammaglobulinemia in a patient with thymoma

Both pure red cell aplasia (PRCA) and hypogammaglobulinemia are rarer conditions than myasthenia gravis (MG) in thymoma patients. Several articles have discussed the relation between PRCA and thymoma or hypogammaglobulinemia and thymoma, and their proper treatments. Instances of both PRCA and hypogammaglobulinemia in a thymoma patient are few and reported sporadically in the literature. We discuss a 46-year-old woman with thymoma and simultaneous PRCA and hypogammaglobulinemia who achieved complete remission from PRCA after perioperative steroid administration and extended thymectomy, and review the literature.

Epoetin-induced pure red cell aplasia: diagnosis and treatment

PURPOSE OF REVIEW

Antibody-mediated pure red cell aplasia is now recognized as a rare complication of erythropoiesis-stimulating agent therapy. The incidence of this adverse effect peaked in 2002, but new cases still appear sporadically. The aim of this review is to discuss the latest opinions regarding the detection and management of this condition.

RECENT FINDINGS

The diagnosis of classical erythropoiesis-stimulating agent induced pure red cell aplasia is made by a constellation of clinical features, including severe transfusion-dependent anaemia, reticulocytopenia, low or absent erythroblasts in the bone marrow, and the presence of circulating antierythropoietin antibodies. Recently, some cases have been reported in which the bone marrow findings show red cell hypoplasia rather than aplasia; this may represent earlier presentations of the same condition.

SUMMARY

Management of pure red cell aplasia as a complication of erythropoiesis-stimulating agent therapy consists of stopping the drug and implementing an immunosuppressive regimen to reduce or abolish erythropoietin antibody production. A recent animal study suggested that a possible alternative strategy may be to administer a novel peptide-based erythropoietin receptor agonist called Hematide that does not cross react with antierythropoietin antibodies, and will allow ongoing stimulation of erythropoiesis; this is the subject of a current clinical trial.

Pure red cell aplasia induced by erythropoiesis-stimulating agents

Pure red cell aplasia in patients who are treated for anemia of chronic kidney disease with erythropoiesis-stimulating agents such as epoetin was first reported in 1998. Although the incidence of pure red cell aplasia peaked in 2002, it remains important for nephrologists to know how to investigate a suspected case of pure red cell aplasia and how to identify other causes of hyporesponsiveness to erythropoiesis-stimulating agents, which account for the vast majority of such cases. The authors reviewed the current status of information in the literature and drew on their personal experiences with patients regarding the diagnosis and management of epoetin-induced pure red cell aplasia. The mechanism for development of epoetin-induced pure red cell aplasia remains unconfirmed. It generally occurs after the production of neutralizing anti-erythropoietin antibodies. Elucidation of a suspected pure red cell aplasia case requires a systematic approach, beginning with simple measurements such as blood cell counts, because most cases of erythropoiesis-stimulating agent hyporesponsiveness are attributable to other causes. If these criteria indicate that the patient's response to erythropoiesis-stimulating agent therapy is very poor, then bone marrow examination and measurement of anti-erythropoietin antibodies is justified. If pure red cell aplasia is confirmed, then cessation of erythropoiesis-stimulating agent therapy and initiation of immunosuppressive therapy are recommended. Continued study of epoetin-induced pure red cell aplasia is needed to help nephrologists prevent or manage future cases and will have implications for the use of other protein-based therapeutic agents.

A case of pure red cell aplasia and systemic lupus erythematosus caused by human parvovirus B19 infection

Human parvovirus B19 (B19) rarely induces pure red cell aplasia (PRCA) in healthy hosts. Meanwhile B19 infection is often clinically similar to systemic lupus erythematosus (SLE), and several cases have been reported wherein B19 actually stimulated SLE exacerbation in an immunocompetent subject. An 82-year-old healthy woman was diagnosed to have complicated with B19 infection and PRCA. Four weeks later, she had high fever, polyarthritis, and oral ulcers, additionally diagnosed with SLE, and subsequently, 15 mg of prednisone was started. This is the first case wherein B19 infection caused both PRCA and SLE in a healthy patient as far as our investigations are concerned.

Myelodysplastic syndrome with erythroid hypoplasia

The incidence of myelodysplastic syndrome (MDS) with erythroid hypoplasia/aplasia is probably underestimated because in most patients it is mistaken for acquired pure red blood cell aplasia. This report describes three children who fulfilled the criteria for MDS with erythroid hypoplasia/aplasia. All these patients had transfusion dependent anaemia, reticulocytopenia, erythroid hypoplasia/aplasia, severe dysgranulopoiesis, and dysmegakaryopoiesis.

Pure red cell aplasia and adult-onset Still?s disease

Pure red cell aplasia (PRCA) associated with adult-onset Still's disease (AOSD) is very rare. In this report a 28-year-old woman was admitted with fever, skin rash, jaundice and anemia. She was diagnosed as having AOSD with PRCA by bone marrow examination. Treatment with high-dose prednisolone and intravenous immunoglobulin resulted in remission of the PRCA and a good response of the AOSD.

Drug-induced myelosuppression : diagnosis and management

Myelosuppression is a common and anticipated adverse effect of cytotoxic chemotherapy. It is a potential but rare idiosyncratic effect with any other drug, but there is a recognised association with a number of higher-risk agents which justify additional vigilance. Genetic risk factors are being identified which may predispose individuals to this reaction with particular drugs. As marker tests become available, dose adjustment or alternative treatment choices may help to avoid more severe reactions. Myelosuppression is potentially life threatening because of the infection and bleeding complications of neutropenia and thrombocytopenia. Strategies for monitoring, early detection, diagnostic confirmation and appropriate supportive care are well developed for cytotoxic therapy. Developments in antimicrobial chemotherapy, blood product transfusion support and growth factor therapy have improved outcomes. These advances are largely applicable to idiosyncratic drug-induced myelosuppression, reinforcing the importance of early recognition and referral to appropriate expertise. Many reactions will resolve on drug withdrawal with appropriate supportive care during the period of cytopenia. Prolonged marrow failure may require more specific treatment with intensive immunosuppression or consideration of bone marrow transplantation.

Pure red cell aplasia associated with parvovirus B19 infection in a patient with ulcerative colitis

Anemia is a common problem that results from various causes in patients with ulcerative colitis (UC), but there is little information on the association of UC with pure red cell aplasia (PRCA). We describe the first case of parvovirus-induced PRCA in UC. A 28-year-old woman with chronic UC was admitted to the hospital for treatment of active pancolitis. Three courses of pulse therapy with methylprednisolone provided complete remission. However, the patient developed reticulocytopenia and a subsequent fall in hemoglobin to 6.2 g/dl. Bone marrow examination revealed selective aplasia of red cell precursors and giant pronoromoblasts. Enzyme immunoassay identified specific immunoglobulin M antibody against parvovirus B19 in the serum. Based on these findings, the diagnosis of PRCA caused by the virus was made. The patient was treated with a 3-day course of intravenous immunoglobulin (5 g/day), resulting in brisk reticulocytosis, folowed by normalization of hemoglobin level. In conclusion, Chronic or acute blood loss in UC associated with enhanced red cell turnover might be a risk factor for PRCA when affected patients contract parvovirus B19 infection.

Anti-cytokine autoantibodies in autoimmunity: preponderance of neutralizing autoantibodies against interferon-alpha, interferon-omega and interleukin-12 in patients with thymoma and/or myasthenia gravis

We have screened for spontaneous anticytokine autoantibodies in patients with infections, neoplasms and autoimmune diseases, because of their increasingly reported co-occurrence. We tested for both binding and neutralizing autoantibodies to a range of human cytokines, including interleukin-1alpha (IL-1alpha), IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-18, interferon-alpha2 (IFN-alpha2), IFN-omega, IFN-beta, IFN-gamma, tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta-1 (TGF-beta1) and granulocyte-macrophage colony stimulating factor (GM-CSF), in plasmas or sera. With two notable exceptions described below, we found only occasional, mostly low-titre, non-neutralizing antibodies, mainly to GM-CSF; also to IL-10 in pemphigoid. Strikingly, however, high-titre, mainly IgG, autoantibodies to IFN-alpha2, IFN-omega and IL-12 were common at diagnosis in patients with late-onset myasthenia gravis (LOMG+), thymoma (T) but no MG (TMG-) and especially with both thymoma and MG together (TMG+). The antibodies recognized other closely related type I IFN-alpha subtypes, but rarely the distantly related type I IFN-beta, and never (detectably) the unrelated type II IFN-gamma. Antibodies to IL-12 showed a similar distribution to those against IFN-alpha2, although prevalences were slightly lower; correlations between individual titres against each were so modest that they appear to be entirely different specificities. Neither showed any obvious correlations with clinical parameters including thymoma histology and HLA type, but they did increase sharply if the tumours recurred. These antibodies neutralized their respective cytokine in bioassays in vitro; although they persisted for years severe infections were surprisingly uncommon, despite the immunosuppressive therapy also used in most cases. These findings must hold valuable clues to autoimmunizing mechanisms in paraneoplastic autoimmunity.

Increased expression of c-maf in pure red cell aplasia secondary to plasma cell dyscrasia

Th2 dominancy in the peripheral T helper (Th) cell subsets were reported to be involved in the pathogenesis of pure red cell aplasia (PRCA). We encountered a PRCA case secondary to plasma cell dyscrasia that showed Th2 dominancy at the relapse of PRCA. Increased expression of c-maf, a transcriptional factor which induces Th2 differentiation of naive T-cells, and elevated expression of interleukin (IL)-4 were observed in the RNA derived from patient's bone marrow at relapse of PRCA. Following the administration of methylprednisolone which improved PRCA, normalization of Th1/Th2 ratio and decreased expression of c-maf and IL-4 were observed, which suggests that the upregulation of c-maf might have played a role in the pathogenesis of PRCA secondary to plasma cell dyscrasia.

Chronic lymphocytic leukemia presenting in association with aplastic anemia

An unusual case of chronic lymphocytic leukemia presenting in association with aplastic anemia is discussed, along with a review of the few previously reported cases. Possible humoral and cellular autoimmune mechanisms are examined as possible causes of marrow aplasia in this setting.

Pure red cell aplasia in a patient with chronic granulocytic leukaemia treated with interferon-alpha

Interferon-alpha has been shown to improve survival in patients with chronic granulocytic leukaemia, therefore it is increasingly becoming part of the standard treatment of this condition. Interferon has a wide variety of side-effects. Pure red cell aplasia has been reported in a few cases of chronic granulocytic leukaemia but this usually heralds the onset of the transformation to the acute phase. This paper reports a possible, and not previously reported, side-effect of interferon-alpha in a patient with chronic granulocytic leukaemia.

Clonal T cell proliferation in patients with pure red cell aplasia

Among the patients with idiopathic pure red cell aplasia (PRCA) who do not meet the diagnostic criteria of chronic lymphocytic leukemia, there are some cases which suggest an association with clonal T lymphocytic proliferation. The morphological characteristics and responses to treatment revealed two distinct groups among the present 13 patients. The lymphocytes in one group were typical granular lymphocytes of T cell phenotype which were treated effectively with cyclophosphamide rather than cyclosporine. The response to therapy in this group occurred after a perceptible reduction in lymphocyte mass, which took at least 8 weeks. The lymphocytes in the second group consisted mainly of non-granulated lymphocytes or some granulated lymphocytes with fine and indistinct granules and responded well to cyclosporine therapy. A reduction in lymphocytes mass was not a prerequisite for the development of the remission of red cell aplasia in this group, and responses occurred within 4 weeks. Clonal T cell proliferation was detected in some patients, which raised the possibility of idiopathic PRCA being associated with a clonal proliferation of T cells. Distinguishing lymphocytes in patients with PRCA could potentially be used to plan treatment strategy and assess prognosis.

Spontaneously occurring neutralizing antibodies against granulocyte-macrophage colony-stimulating factor in patients with autoimmune disease

There is increasing evidence that spontaneous anticytokine autoantibodies are associated with chronic infections and autoimmune diseases. We report the sporadic occurrence in autoimmune diseases of such autoantibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine involved in inflammation and the regulation of proliferation, differentiation and function of granulocytic and monocytic cell lineages. In 41 of 425 patients tested, we found low to moderate levels of autoantibodies binding to GM-CSF in serum or plasma. These were most prevalent in patients with myasthenia gravis (MG). However, neutralizing autoantibodies against GM-CSF were very rare, being found in only three patients. Two had autoimmune MG, one with thymoma (Patient A) and the other (Patient B) with 'seronegative' MG, i.e. without the antiacetylcholine receptor autoantibodies characteristic of most MG patients, and a third (Patient D) had multiple sclerosis. Only very limited amounts of Patient A and Patient D serum/plasma were available for analysis and therefore further studies were carried out on the more plentiful samples from Patient B. The anti-GM-CSF autoantibodies of Patient B were predominantly polyclonal immunoglobulin G and strongly neutralized recombinant human (rh) GM-CSF derived from different expression systems. They had similar immunological and immunochemical characteristics to anti-GM-CSF antibodies that developed in immunocompetent colorectal carcinoma patients following (rh)GM-CSF therapy. In serial samples from Patient B, the anti-GM-CSF autoantibodies were undetectable from diagnosis at age 8 years until at least age 13, but then developed spontaneously during (temporary) withdrawal of immunosuppressive treatment. Their neutralizing activity has persisted since their first detection at age 15 years 1 month, and was at its highest level recently at age 17 years 7 months. There was no obvious association with other autoimmune phenomena, nor were any haematological deficiencies overtly manifested, suggesting that any loss of GM-CSF function may have been compensated for by other cytokines.

Pure red cell aplasia as presentation of systemic lupus erythematosus: antibodies to erythropoietin

In this case report we describe two patients with pure red cell aplasia (PRCA) as an initial manifestation of systemic lupus erythematosus (SLE). Antibodies to erythropoietin were determined, by an ELISA method developed in our laboratory, in frozen serum obtained from one of the patients. A high titer of antibodies to erythropoietin was detected in serum obtained before treatment with high dose intravenous immunoglobulin (IVIG). The antibody titer declined after successful treatment. This observation suggests that antibodies to erythropoietin may contribute to the pathogenesis of SLE associated PRCA.

Pure red cell aplasia and myasthenia gravis with thymoma: a case report and review of the literature

A case of pure red cell aplasia (PRCA), myasthenia gravis (MG) and thymoma is reported. A 70-year-old woman presented with severe anemia. She had been diagnosed as having MG 8 years earlier and her symptoms were adequately controlled with ambenonium chloride. When she visited our hospital, her hematocrit was 13.7% with a hemoglobin concentration of 4.7 g/dl and her reticulocyte counts were persistently abnormal at 0.1%. Although both direct and indirect Coombs' tests were positive, there was no evidence of hemolysis. Routine screening tests for other etiologies of anemia were negative. Serological tests for anti-DNA and anti-acetylcholine receptor antibodies gave positive results. A bone marrow examination revealed severe erythroid hypoplasia. PRCA was diagnosed and the patient was treated with periodic transfusions. A lateral view chest roentgenogram and a computed tomography scan of the thorax showed the presence of an anterior mediastinal mass which was suspected to be thymoma. The patient underwent thymothymectomy and the tumor was diagnosed as a thymoma. Although the patient received no treatment for MG and PRCA after surgery, her hematological test results rapidly improved and she was discharged from the hospital on the 29th postoperative day. At that time, her hematocrit was 33.2%, her hemoglobin concentration was 10.0 g/dl, her peripheral reticulocyte level was 1.8% and her left partial ptosis had improved. She is doing well, 9 months after surgery. For a patient to remain in remission without treatment for PRCA and MG after thymothymectomy is extremely rare.

Pure red cell aplasia in a man with RA

A 65 year-old man with long-standing rheumatoid arthritis (RA) developed pure red cell aplasia (PRCA), which was apparently not caused by drugs or viral infections. The condition responded favorably to danazol in combination with sulfasalazine. This was probably the 2nd case of RA with PRCA in a male patient.

Haematological disorders associated with feline retrovirus infections

Feline oncornavirus and lentivirus infections have provided useful models to characterize the virus and host cell factors involved in a variety of marrow suppressive disorders and haematological malignancies. Exciting recent progress has been made in the characterization of the viral genotypic features involved in FeLV-associated diseases. Molecular studies have clearly defined the causal role of variant FeLV env gene determinants in two disorders: the T-lymphocyte cytopathicity and the clinical acute immunosuppression induced by the FeLV-FAIDS variant and the pure red cell aplasia induced by FeLV-C/Sarma. Variant or enFeLV env sequences also appear to play a role in FeLV-associated lymphomas. Additional studies are required to determine the host cell processes that are perturbed by these variant env gene products. In the case of the FeLV-FAIDS variant, the aberrant env gene products appear to impair superinfection interference, resulting in accumulation of unintegrated viral DNA and cell death. In other cases it is likely that the viral env proteins interact with host products that are important in cell viability and/or proliferation. Understanding of these mechanisms will therefore provide insights to factors involved in normal lymphohaematopoiesis. Similarly, studies of FeLV-induced haematological neoplasms should reveal recombination or rearrangement events involving as yet unidentified host gene sequences that encode products involved in normal cell growth regulation. These sequences may include novel protoncogenes or sequences homologous to genes implicated in human haematological malignancies. The haematological consequences of FIV are quite similar to those associated with HIV. As with HIV, FIV does not appear to directly infect myeloid or erythroid precursors, and the mechanisms of marrow suppression likely involve virus, viral antigen, and/or infected accessory cells in the marrow microenvironment. Studies using in vitro experimental models are required to define the effects of each of these microenvironmental elements on haematopoietic progenitors. As little is known about the molecular mechanisms of FIV pathogenesis, additional studies of disease-inducing FIV strains are needed to identify the genotypic features that correlate with virulent phenotypic features. Finally, experimental FIV infection in cats provides the opportunity to correlate in vivo virological and haematological changes with in vitro observations in a large animal model that closely mimics HIV infection in man.

Pure red cell aplasia associated with malignant thymoma, myasthenia gravis, polyclonal large granular lymphocytosis and clonal thymic T cell expansion

A case with the triad of pure red cell aplasia (PRCA), myasthenia gravis, and malignant thymoma is reported. There was a clonal proliferation of T cells within the thymoma, as demonstrated by a T cell antigen receptor (TCR) delta chain gene rearrangement. However, despite a large granular lymphocytosis, clonality could not be shown in the peripheral blood either before or after thymectomy. There was no evidence of human T cell lymphotrophic virus type 7 (HTLV1) infection. It is postulated that the clonal thymic T cell population secreted cytokine(s), which stimulated the polyclonal proliferation of large granular lymphocytes, which in turn suppressed erythropoiesis. Thymectomy removed the stimulus to the large granular lymphocytes and hence there was a resurgence of erythropoiesis.

Pure red cell aplasia after chemotherapy for Hodgkin's lymphoma: in vitro evidence for T cell mediated suppression of erythropoiesis and response to sequential cyclosporin and erythropoietin

Acquired pure red cell aplasia (PRCA) has been associated with various lymphoproliferative conditions but its occurrence with Hodgkin's disease is rare. We report a case of PRCA occurring immediately following the completion of induction chemotherapy in a patient with Stage IIIB nodular sclerosing Hodgkin's disease. In vitro erythroid colony studies documented evidence for T cell mediated suppression of erythropoiesis and lack of a serum inhibitor. Addition of cyclosporin to the in vitro cultures stimulated erythroid colony growth. Following in vivo treatment with cyclosporin peripheral blood CD4/CD8 ratios returned to normal. However, serum erythropoietin levels were inappropriately low. Subsequent treatment with erythropoietin induced a reticulocytosis and transfusion independence. Since discontinuing the erythropoietin, the patient has been able to maintain a hemoglobin of 100 g/L. This case illustrates that red cell aplasia occurring in the setting of Hodgkin's disease may be due to T cell mediated suppression of erythropoiesis. A response to cyclosporin may be masked by inappropriately low erythropoietin levels.

Prolonged, pregnancy-related pure red cell aplasia; a case report

We describe the clinical course of a patient with pregnancy-related, acquired, pure red cell aplasia (PRCA). The course of PRCA was prolonged and ultimately responded only to corticosteroids. It did not recurr over 4 years of observation despite another gestation, and no other cause for PRCA could be detected during this long period.

A B cell line from a patient with pure red cell aplasia produces an immunoglobulin that suppresses erythropoiesis

A 4-year-old boy with pure red cell aplasia was investigated. Immunophenotypic analysis of peripheral blood lymphocytes revealed a marked increase of CD20+ cells, which fell from 25.9% in the active stage to 9.7% in remission. The plasma contained a suppressive activity against CFU-e and BFU-e formation by the patient's bone marrow cells, which disappeared when the disease went into remission. Prednisone (2 mg/kg/day) therapy was tried for 5 weeks, but produced no improvement. Subsequently, high-dose gamma-globulin therapy induced complete remission of anemia. A lymphoblastoid B cell line obtained from the patient before therapy produced a factor that suppressed erythropoiesis but not granulopoiesis. The suppressive activity resided in the immunoglobulin fraction and was adsorbed by an anti-immunoglobulin column. These results indicate that expansion of B cells producing an immunoglobulin which suppressed erythropoiesis was involved in the pathogenesis of the disease in this patient.

Red cell aplasia in myelodysplastic syndrome

Six cases of red cell aplasia occurring in patients with myelodysplastic syndromes (MDS) showed a diversity of clinical course and prognosis. In some patients red cell aplasia may have represented an evolution of MDS while in others autoimmune destruction of erythoblasts may have been the mechanism. A proliferative phase is seen in many of these patients, the clinical importance of which is uncertain.

Pure red cell aplasia associated with B cell lymphoma: demonstration of bone marrow colony inhibition by serum immunoglobulin

A 58-year old male with follicular small cleaved B cell lymphoma developed pure red cell aplasia (PRCA) during chemotherapy. To understand the etiology of the PRCA, we studied the effects of patient sera on the progenitor cell colony formation of normal human bone marrow cells in vitro. We demonstrated a marked inhibition of normal bone marrow progenitor cell colony formation by patient sera, but not pooled normal human sera. Immunoglobulin was then precipitated from patient sera for similar studies. The majority of the precipitated immunoglobulin was of the IgG type. The immunoglobulin fraction markedly inhibited normal bone marrow progenitor cell colony formation, whereas the non-immunoglobulin fraction was not inhibitory. The presence of inhibitory serum immunoglobulin correlated with the hematologic status of the patient. We conclude that the development of PRCA in patients with B cell lymphoma may be due to a serum IgG inhibitor of bone marrow progenitor cell growth.

A report of a case with pure red cell aplasia induced by sodium valproate

A 5-year-old girl developed pure red cell aplasia (PRCA) during sodium valproate (VPA) administration. Only four cases of VPA induced PRCA have been reported in the literature. Furthermore no precise report concerning the underlying mechanisms is available. Using a system for the clonal growth of autologous bone marrow committed erythroid stem cells (CFU-E, BFU-E) VPA itself was not inhibitory for colony formation at a physiological concentration. Patient's serum and peripheral mononuclear cells collected at admission showed no inhibitory effects on erythroid progenitor cell growth. Rapid recovery from PRCA was observed after discontinuation of VPA, without immunosuppressive therapy. Our observation suggests that VPA may induce PRCA through the inhibitory effect beyond the differentiation stage of BFU-E and CFU-E in some cases.

Drug-induced red cell dyscrasias

Major advances have been made in recent years in our understanding of the pathogenetic mechanisms of drug-induced blood dyscrasias, particularly those involving the red cell. Among the latter, hemolytic anemia is the most common. Drug-induced red cell destruction may occur on an immune basis or through disruption by the drug of red cell metabolism. The immunological basis of drug-induced hemolysis is reviewed with emphasis on the clinical and laboratory manifestations, differential diagnosis and the major mechanisms involved. Drug-induced oxidative hemolysis both in normal individuals and in those with certain enzymopathies, notably glucose-6-phosphate dehydrogenase deficiency, is summarized. Drugs may also produce red cell dyscrasias by acting on the immature erythroid compartment. Some of these inhibit erythroid growth by as yet poorly understood mechanisms. Others exert more specific metabolic effects in erythroid precursors. These include drugs which interfere with DNA synthesis causing megaloblastic erythropoiesis and those which disrupt mitochondrial function and the synthesis of heme manifested by sideroblastic erythropoiesis. A brief consideration of heme biosynthesis and the action of drugs which are associated with sideroblastic anemia, including the antituberculous agents, lead, alcohol and chloramphenicol is presented. Finally, where pertinent, an updated listing of drugs involved in red cell dyscrasias is included.

Response of agranulocytosis to thymectomy in a patient with thymoma and chronic lymphocytic leukemia

A patient with chronic lymphocytic leukemia presented with recurrent episodes of severe neutropenia. This neutropenia was initially responsive to prednisone but eventually became refractory. A spindle-cell thymoma was diagnosed and resected with dramatic improvement in his granulocytopenia. Both autologous and heterologous granulocyte macrophage colony growth were clearly inhibited by the patient's serum. This is the first reported case of severe granulocytopenia associated with a thymoma that seemed to be reversed following thymectomy.