The use of monoclonal antibodies in immune-mediated hematologic disorders

In this article, the evidence on the clinical use of monoclonal antibodies in the treatment of immune-mediated hematologic disorders is described. Insights into pathogenic mechanisms have revealed a major role of both B and T cells. Controlled trials have shown conflicting results, necessitating further research regarding pathogenesis, mechanism of action, and resistance. Although the use of more potent and specific monoclonal antibody therapy, mainly targeting costimulation signals, may improve response rates and long-term outcome, its use should be carefully balanced against potential side effects.

Outcomes after major or bidirectional ABO-mismatched allogeneic hematopoietic progenitor cell transplantation after pretransplant isoagglutinin reduction with donor-type secretor plasma with or without plasma exchange

BACKGROUND

Major ABO mismatch in hematopoietic progenitor cell transplantation (HPCT) is associated with a range of immunohematologic consequences including progenitor cell infusion (PCI)-related hemolysis, delayed red blood cell engraftment, and pure red cell aplasia (PRCA). Although pretransplant (recipient) isoagglutinin reduction may be associated with decreased immunohematologic complications in this setting, there is no consensus with respect to strategies for isoagglutinin reduction.

STUDY DESIGN AND METHODS

This observational study assessed the efficacy of a standardized pretransplant isoagglutinin reduction strategy incorporating donor-type secretor plasma infusions with or without plasma exchange to prevent PCI-associated hemolysis and PRCA in major or bidirectional ABO-mismatched peripheral blood HPCT. All major or bidirectional ABO-mismatched HPCTs performed between 1999 and 2010 were identified from an institutional database. Immunohematologic outcomes were determined retrospectively by review of individual medical records.

RESULTS

In total 110 major or bidirectional ABO-mismatched HPCTs had been performed. No patient developed hemolysis after PCI. With respect to PRCA incidence, 16 patients (15%) were excluded due to early mortality and three (3%) due to incomplete data; of the remaining 91 patients, five (5%) developed PRCA. Patients with PRCA had significantly higher pretransplant isoagglutinin titers (p = 0.0001) compared to those who did not develop PRCA.

CONCLUSIONS

Use of a standardized pretransplant isoagglutinin reduction strategy including donor-type secretor plasma infusions is both safe and efficient in preventing PCI-associated hemolysis and is associated with low rates of posttransplant PRCA.

CD4+CD25highFoxP3+ regulatory T-cells in hematologic diseases

BACKGROUND

CD4+CD25+ regulatory T-cells (Tregs) play a critical role in immune responses. We explored the status of Tregs in neoplastic and autoimmune hematologic diseases. We also evaluated the technical aspects of Treg measurement in terms of sample type and detection markers.

METHODS

A total of 68 subjects were enrolled: 11 with AML, 8 with MDS, 10 with autoimmune diseases, and 39 controls. Tregs were analyzed in peripheral blood (PB) and bone marrow (BM) samples from each subject. Flow cytometry and the Human Regulatory T cell Staining Kit (eBioscience, USA) for CD4, CD25, and FoxP3 (forkhead box P3) were used.

RESULTS

The CD4+CD25(high)/CD4 and CD4+CD25(high)FoxP3+/CD4 populations were significantly correlated (P<0.0001). The AML and high-risk MDS groups had significantly larger CD4+CD25(high)/CD4 and CD4+CD25(high)FoxP3+/CD4 populations in PB than the autoimmune (P=0.007 and 0.012, respectively) and control groups (P=0.004 and 0.006, respectively). Comparable findings were observed in BM. The CD4+CD25(high)FoxP3+/CD4 population was significantly larger in PB than in BM (P=0.0003).

CONCLUSIONS

This study provides comparison data for Tregs in AML, MDS, and autoimmune hematologic diseases, and would be helpful for understanding the different immunologic bases of various hematologic diseases. Treg measurement using CD4, CD25, and/or FoxP3 in PB rather than in BM seems to be practical for routine hematologic purposes. Large-scale analysis of the diagnostic role of Treg measurement is needed.

Rituximab therapy for autoimmune haematological diseases

Autoimmune haematological diseases are characterized by the production of antibodies against blood proteins or cells, and comprise primary immune thrombocytopenia, autoimmune haemolytic anaemia, acquired haemophilia, and thrombotic thrombocytopenic purpura. Current treatments for these disorders include corticosteroids, cytotoxic drugs and splenectomy, which may be associated with significant systemic toxicity and/or morbility. B cells play a key role in both the development and perpetuation of autoimmunity, since they produce autoantibodies but also function as antigen-presenting cells, and release immunomodulatory cytokines. Rituximab, an anti-CD20 monoclonal antibody that specifically depletes B cells, may be an effective treatment strategy for patients with autoimmune disorders. This article reviews data of the literature, showing that patients with autoimmune haematological diseases can respond to rituximab irrespective of age and number or type of prior treatments. These data suggest that rituximab provides an effective and well-tolerated treatment option for these conditions.

[Comparison of curative efficacy after G-CSF-mobilized sibling HLA-matched peripheral blood hematopoietic stem cell transplantation versus that combined with BMT for patients with hematologic malignancies in a single center]

This study was aimed to retrospectively analyze and compare the clinical curative efficacy of patients with hematologic malignancies after G-CSF-mobilized sibling HLA-matched (sm) peripheral blood hematopoietic stem cell transplantation (sm-allo-PBHSCT) and sm-allo-PBHSCT combined with bone marrow transplantation (BMT). 100 patients received sm-allo-HSCT in a single center from October 2001 to October to 2010, included 38 patients received sm-allo-PBHSCT and 62 patients received sm-allo-PBHSCT combined with BMT. The myeloablative or reduced intensity conditioning regimens were chosen according to the condition of patients. All patients received standard cyclosporine (CsA) and mycophenolate mofetil (MMF) as prophylaxis for GVHD. The results showed that the rapid hematopoietic reconstitution was observed in all patients. The median time of ANC ≥ 0.5 × 10(9)/L in both groups were 12 days, the median time of platelet count ≥ 20 × 10(9)/L was 15 days in sm-allo-PBHSCT group and 16 days in sm-allo-PBHSCT + BMT group. The incidence of acute GVHD, acute GVHD of III-IV grade and chronic GVHD in sm-allo-PBHSCT and sm-allo-PBHSCT + BMT groups were 37.1% and 34.2%, 7.89% and 8.06%, 36.11% and 41.38% respectively, there were no statistical differences. The relapse rates were similar in two groups (sm-allo-PBHSCT 13.16% vs sm-allo-PBHSCT + BMT 12.9%). The 3-year disease-free survivals in sm-allo-PBHSC and sm-allo-PBHSCT + BMT groups were 57.1 ± 8.7% and 61.3 ± 6.4% respectively (p = 0.852). The 2-year overall survival of high-risk patients was 41.4 ± 12.8% in sm-allo-PBHSCT group, while 60.9 ± 9.6% in sm-allo-PBHSCT + BMT group (p = 0.071). It is concluded that the rhG-CSF mobilized sibling matched allo-PBHSCT + BMT is superior to the rhG-CSF mobilized sibling matched allo-PBHSCT in increasing the overall survival of high-risk hematologic malignancies.

Innate immunity as orchestrator of stem cell mobilization

Hematopoietic stem and progenitor cells (HSPCs), as well as other types of stem cells, circulate under steady-state conditions at detectable levels in peripheral blood (PB), with their numbers increasing in response to stress, inflammation and tissue/organ injury. This mobilization process may be envisioned as a danger-sensing response mechanism triggered by hypoxia or mechanical or infection-induced tissue damage that recruits into PB different types of stem cells that have a role in immune surveillance and organ/tissue regeneration. Mobilization is also significantly enhanced by the administration of pharmacological agents, which has been exploited in hematological transplantology as a means to obtain HSPCs for hematopoietic reconstitution. In this review we will present mounting evidence that innate immunity orchestrates this evolutionarily conserved mechanism of HSPC mobilization.

How I treat common variable immune deficiency

Common variable immunodeficiency is a rare immune deficiency, characterized by low levels of serum immunoglobulin G, A, and/or M with loss of antibody production. The diagnosis is most commonly made in adults between the ages of 20 and 40 years, but both children and older adults can be found to have this immune defect. The range of clinical manifestations is broad, including acute and chronic infections, inflammatory and autoimmune disease, and an increased incidence of cancer and lymphoma. For all these reasons, the disease phenotype is both heterogeneous and complex. Contributing to the complexity is that patient cohorts are generally small, criteria used for diagnosis vary, and the doses of replacement immune globulin differ. In addition, routines for monitoring patients over the years and protocols for the use of other biologic agents for complications have not been clarified or standardized. In the past few years, data from large patient registries have revealed that both selected laboratory markers and clinical phenotyping may aid in dissecting groups of subjects into biologically relevant categories. This review presents my approach to the diagnosis and treatment of patients with common variable immunodeficiency, with suggestions for the use of laboratory biomarkers and means of monitoring patients.

[Paraneoplastic autoimmune disorders]

Paraneoplastic syndrome is defined as tumor-associated symptoms and signs not related to the physical effects of primary or metastatic tumors. The mechanisms of this syndrome include the production of bioactive soluble factors by tumor cells and autoimmune diseases elicited by the immune responses against tumors. Production of bioactive soluble factors causes endocrinologic symptoms. The paraneoplastic autoimmune process may affect the nervous system, cutaneous tissue, musculoskeletal system, hematopoietic cells or kidneys. Paraneoplastic rheumatic diseases show symptoms similar to inflammatory myopathy, polyarthritis, vasculitis, cryoglobulinemia and polymyalgia rheumatica. Rapid onset, unusual age, asymmetrical involvement of joints or refractoriness to standard immunosuppressive therapy suggests the presence of paraneoplastic autoimmune diseases. Autoimmune hematopoietic disorders include pure red cell aplasia, autoimmune hemolytic anemia and thrombocytopenia. Unexplained anemia or thrombocytopenia may indicate the presence of lymphoid neoplasms. Membranous nephropathy is a well-known glomerular disease associated with malignancy, and membranoproliferative glomerulonephritis, minimal change nephrotic syndrome, and antineutrophil cytoplasmic antibody(ANCA)-associated crescentic glomerulonephritis may be seen in cancer patients. Age and sex-appropriate cancer screening should be performed in patients with nephrotic syndrome due to membranous nephropathy.

Allogeneic hematopoietic cell transplantation: the state of the art

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative procedure for a variety of hematologic malignancies. The field has evolved substantially over the past decade, with advances in patient and donor selection, stem cell sources, supportive care, prevention of complications and reduced-toxicity preparative regimens. As a result, the indications for HCT and the pool of eligible patients have expanded significantly. In this article, we provide an overview of the major aspects of allogeneic HCT, and focus specifically on areas of active research and on novel approaches to challenges in the field. Specifically, we will discuss approaches to reduce the toxicity of the preparative regimen, with the goal of increasing the safety and applicability of HCT. The availability of suitable donors may be an obstacle to wider application of HCT. We review three major approaches to broadening the donor pool: the use of HLA-mismatched unrelated donors, umbilical cord blood and HLA-haploidentical family donors. Graft-versus-host disease remains a major cause of morbidity and mortality after HCT. We review recent advances in the understanding of this phenomenon, and novel prophylactic and therapeutic approaches that hold the promise of further improving the safety of the procedure. We conclude with a speculative outline of the next 5 years of research in the field of HCT.

[Comparison of immunological reconstitution and related complications after HLA-matched and HLA haploidentical peripheral blood hematopoietic stem cell transplantation]

OBJECTIVE

To explore the difference of immune function and relationship with main complications after HLA-matched and HLA haploidentical allogeneic peripheral blood hematopoietic stem cell transplantation (allo-PBSCT).

METHODS

Sixty-seven patients undergoing HLA-matched (n = 33) or HLA haploidentical (n = 34) allo-PBSCT during the same time period in our hospital from June 2004 to December 2007 were included in this study. Indirect immunofluorescence assay was employed to detect lymphocyte subsets before transplantation and on month 1, 3, 6, 12 and 18 after transplantation and the lymphocyte subsets of 100 healthy people were used as normal control. The comparison of immunological reconstitution and relationship with main complications was carried out with statistical analysis.

RESULTS

(1) Comparison of the 67 patients with normal controls showed that CD(3)(+), CD(4)(+), CD(4)(+)/CD(8)(+) at month 1, CD(4)(+), CD(4)(+)/CD(8)(+) at month 3 and CD(4)(+) at month 6 after PBSCT were lower. CD(8)(+) at month 3 and month 6 were higher. (2) The immune function was not statistically different between HLA haploidentical and HLA-matched allo-PBSCT (P > 0.05). (3) The immune function of patients with and without severe infection was not statistically different (P > 0.05). (4) The immune function of patients with chronic graft-versus-host disease (cGVHD) between HLA haploidentical and HLA-matched allo-PBSCT groups was not statistically different. The immune function of patients without cGVHD in two groups was not statistically different (P > 0.05). (5) The immune function of patients with or without relapse was not statistically different (P > 0.05).

CONCLUSIONS

HLA-haploidentical PBSCT conditioning including antithymocyte globulin without in vitro T cell depletion is feasible and safe. The immunological reconstitution, incidence of severe infection, incidence of relapse and treatment-related mortality are not significantly different between HLA-matched and HLA haploidentical allo-PBSCT.

Adverse drug reactions affecting blood cells

Numerous medications and other xenobiotics are capable of producing adverse reactions (ADRs) affecting red cells, platelets or neutrophils. Occasionally, more than one blood element is affected simultaneously. As with all drug reactions, some side effects are a direct consequence of a known pharmacologic action of the drug and are dose-dependent; others occur sporadically and relatively independent of dose. The latter ("idiosyncratic") reactions are unpredictable and, in general, have no known underlying genetic basis. Many are antibody-mediated, as would be expected since cellular immune effector cells have little direct access to circulating blood cells. In this chapter, we will discuss idiosyncratic drug reactions affecting blood and blood forming tissues with an emphasis on those thought to be immune-mediated.

CXCR4 in clinical hematology

Pharmacological manipulation of CXCR4 has proven clinically useful for mobilization of stem and progenitor cells and in several preclinical models of disease. It is a key component in the localization of leukocytes and stem cells. For patients with multiple myeloma and non-Hodgkin's Lymphoma, treatment with plerixafor, an inhibitor of CXCL12 binding to CXCR4, plus G-CSF mobilizes stem cells for autologous transplantation to a greater degree than the treatment with G-CSF alone, and in some cases when patients could not be mobilized with cytokines, chemotherapy, or the combination. Stem cells from healthy donors mobilized with single agent plerixafor have been used for allogeneic transplantation in acute myelogenous leukemia (AML) patients, although this is still in the early phase of clinical development. Plerixafor is also undergoing evaluation to mobilize tumor cells in patients with AML and chronic lymphocytic leukemia (CLL) to enhance the effectiveness of chemotherapy regimens. Plerixafor's effect on neutrophils may also restore circulating neutrophil counts to normal levels in patients with chronic neutropenias such as in WHIMs syndrome. Other areas where inhibition of CXCR4 may be useful based upon preclinical or clinical data include peripheral vascular disease, autoimmune diseases such as rheumatoid arthritis, pulmonary inflammation, and HIV.

The ratio between CD4 + and CD8 + cells in the peripheral blood of patients with hematological malignancies is not altered by thalidomide

Thalidomide is thought to have anti-angiogenic and immunomodulatory properties, including suppression of tumor necrosis factor-alpha, effects on interleukins and interferons, down-regulation of some cell adhesion molecules, and changes in the proportion of lymphocyte subsets. It is unclear whether the clinical response to thalidomide in patients with multiple myeloma (MM), idiopathic myelofibrosis (IM), and myelodysplastic syndromes (MDS) is related to its ability to inhibit angiogenesis or its immunomodulatory effects. We examined the effect of thalidomide on T-lymphocyte subsets in 18 patients with MDS, 6 patients with MM, 4 patients with IM, and 3 patients with angioimmunoblastic lymphoma (AILD). These patients had either a relapse or progressive disease following cytotoxic chemotherapy including high-dose chemotherapy with autologous stem cell support. Thalidomide was first administered at 100 mg/day p.o. and increased to 400 mg/day. T-lymphocyte subsets (CD4+, CD8+) were measured by fluorescence-activated cell sorter (FACS) before and during treatment with thalidomide. Twenty-six of 31 patients responded to thalidomide, most of them achieving partial remission. The median concentration of CD4+ cells was 443/microl, the median of CD8+ cells was 359/microl (CD3 992/microl). In our cohort, no significant changes in absolute numbers or proportions of CD3+ (P = 0.12), CD4+ (P = 0.668), or CD8+ (P = 0.143) cells were observed following the treatment with thalidomide. Although the CD4/CD8 ratio declined from 1.6 to 1.0 during 3 months of thalidomide treatment, this had no statistical significance (P = 0.1). Our findings show that an effect of thalidomide on the T lymphocytes studied is unlikely to be of major importance for the clinical effects.

[Factors influencing engraftment in hematological patients after human leukocyte antigen matched sibling allogeneic blood and marrow transplantation]

OBJECTIVE

To investigate the factors influencing engraftment in patients with hematological diseases after human leukocyte antigen matched sibling allogeneic blood and marrow transplantation.

METHODS

One hundred and fifty-seven patients with hematological diseases who underwent allogeneic blood and marrow transplantation were enrolled in this study. The cell compositions in allografts were determined using multi-color flow cytometry.

RESULTS

The median time for the engraftment of neutrophil and platelet was 15 (11-25) days and 12 (7-78) days, respectively. Univariate analyses demonstrated that the source of allografts (P = 0.049) and allograft-infused cell doses of CD34+ cells (P = 0.001) was correlated with neutrophil engraftment. The duration from diagnosis to transplantation (P = 0.043) and allograft-infused cell doses of CD cells (P < 0.001) were correlated with platelet engraftment. Multivariate analysis showed that allograft-infused cell doses of CD34+ cells were associated with a rapid neutrophil recovery (RR: 1.222, 95% CI: 1.063-1.405, P = 0.005) and platelet reconstitution (RR: 1.228, 95% CI: 1.090-1.382, P = 0. 001), the duration from diagnosis to transplantation was associated with platelet recovery (RR: 1.000, 95% CI: 0.999-1.000, P = 0.065). A significantly faster recovery of neutrophils (14.5 d) and platelets (11 d) was found in patients infused > 2.45 x 10(6)/kg CD34+ cells as compared with those (16 d and 14 d) infused < or = 2.45 x 10(6)/kg CD34+ cells (P = 0.021, 0.010, respectively).

CONCLUSION

The absolute number of CD34+ cell in allografts was a main factor influencing the engraftment of neutrophil and platelet after HLA-matched sibling allogeneic blood and marrow transplantation. Duration from diagnosis to transplantation was another factor influencing engraftment of platelet.

Anti‐N‐Like and Anti‐Form Red Cell Antibodies in Chronic Hemodialysis Patients

Allogeneic red blood cell (RBC) transfusions and the use of reusable dialyzers sterilized with formaldehyde can lead to RBC alloimmunization in chronic hemodialysis patients. The formed RBC alloantibodies have been implicated in immediate kidney allograft failure and decreased RBC survival observed in these patients. Using indirect antiglobulin test, direct antiglobulin test (DAT), and direct Polibrene test (DPT), we detected an RBC alloimmunization rate of 17.2% (11/64) in transfused hemodialysis patients, and found the presence of anti-N-like and anti-Form antibodies in 5 (5.7%) and 53 (60.9%) individuals, respectively. The sensitivity rate of the DPT was significantly higher than that of the DAT in detecting anti-Form, but the DAT showed a higher specificity rate compared with the DPT. We conclude that patients treated with reusable dialyzers sterilized with formaldehyde may develop specific RBC alloantibodies that could increase the potential risk of hemolysis, decrease survival of RBCs, and increase the need of blood supply.

Pneumococcal vaccination in splenectomized patients with hematological disorders

Seventy splenectomized patients were vaccinated with Pneumovax, a pneumococcal polysaccharide vaccine. Twenty-four of the patients had a malignant and 30 a nonmalignant hematological disorder. The remaining 16 were patients with no known hematological disorder, seven with intra-abdominal carcinomas and nine with non-malignant reasons for splenectomy. About 90% of the patients with non-malignant hematological disorders responded to vaccination with a rise in antibody titres, which was significantly higher than in the other two groups studied. Malignant hematological disorders lowered the response rate to 61-67%. Patients with no known hematological disorder but with intra-abdominal carcinomas also responded less frequently, while those in this group with other surgical reasons for splenectomy had a response rate comparable to healthy individuals. No serious side-effects were reported and we therefore conclude that all splenectomized patients should be vaccinated with a pneumococcal vaccine. However, it must always be born in mind that one third of the patients with malignant disease did not respond to vaccination.

[Objectives and organization of a reference center for autoimmune cytopenia in adults]

French public health legislation passed in August 2004 made orphan diseases one of five major priorities. The main aims were to improve healthcare access and quality. One hundred thirty-two centers were certified. In 2005, our group was certified for the treatment of adult patients with autoimmune cytopenia, and for related research. Our reference center consists of eight teams located in the Paris area (6 teams), Lille and Caen, and 19" centers of competence" covering the whole of France. The reference and competence centers' main tasks are to provide expertise, referral, research and healthcare organization in the field of purp autoimmune cytopenias.

New treatment options for immune-mediated hematological disorders

In recent years, there has been a tremendous increase in the number of clinical studies with monoclonal antibodies and small molecules in the treatment of hematological malignancies. Clinical observations have shown that some of these molecules may also aid in the treatment of immune-mediated hematological disorders. Moreover, immunotherapy has become an important treatment cornerstone in other, non-hematological, auto-immune diseases. This paper reviews the current state of the use of these new molecules in the treatment of the most frequently encountered immune-mediated hematological disorders: auto-immune hemolytic anemia (AIHA), idiopathic thrombocytopenic purpura (ITP), and thrombotic thrombocytopenic purpura (TTP).

[Auto-immune serological disorders in chronic viral C hepatitis: prevalence and clinical significance]

BACKGROUND

Hepatitis C viral (HCV) infection has been shown to lead to auto-immune phenomena.

AIMS

We review the prevalence of serological auto-immune disorders associated to HCV infection and to clarify their clinical significance.

METHODS

Literature review.

RESULTS

The serological immune response to HCV infection may include the development of cryoglobulinemia, rheumatoid factor, anticardiolipin, antinuclear, anti-liver-kidney-microsome 1 and anti-smooth muscle antibodies. Serological auto-immune manifestations were explained by the lymphotropism of HCV and the polyclonal activation of B cells. Interferon-based treatment of HCV infection may precipitate or exacerbate the associated auto-immune disease.

CONCLUSION

In patients with serological auto-immune disorders associated with HCV infection, a very careful analysis of clinical and biological features is needed. Application of classification criteria of systemic auto-immune diseases and testing more specific antibodies can resolve this point.

Abbreviated dose rituximab for immune-mediated hematological disorders

As rituximab, a monoclonal antibody targeting CD20, depletes B cells, there is considerable interest in its use in immune-mediated disorders. The majority of studies employ a four-dose regimen based on practice in lymphoma therapy. We describe our experience with one or two doses of 375 mg/m(2) of rituximab in 12 patients with relapsed and refractory immune-mediated hematological disorders. Eleven patients (92%) achieved a complete remission that has been sustained in 7 for a median of 14.5 (10.5-22) months. Four patients (36%) relapsed after responses of 1-18.5 months. This preliminary experience suggests that one or two doses of rituximab may have response and relapse rates comparable to multidose regimens while potentially providing considerable cost savings. Further prospective studies are planned.

[Characteristics of chronic active Epstein-Barr virus infection-associated hematological disorders in children]

The aim of this study was to analyze characteristics of chronic active Epstein-Barr virus (CAEBV) infection associated hematological disorders in children. Clinical characteristics were summarized; the morphology of hematopoietic cells in bone marrow was observed by microscopy; the lymphocyte subpopulations were analyzed by flow cytometry; the immunophenotype of liver biopsies was assayed by immunohistochemistry; EBV-related antibodies were measured by ELISA; serum EBV-DNA loads were detected by real-time quantitative PCR; EBV-encoded small RNA 1-positive cells in peripheral blood mononuclear cells were identified by in situ hybridization. The results indicated that the clinical manifestations in patients included persistent or recurrent fever, hepatosplenomegaly, liver dysfunction, anemia, thrombocytopenia, systemic inflammatory reaction. Bone marrow presented as hypocellularity, dysmaturation, myelodysplasia and hemophagocytosis. CD8(+) cell high counts were demonstrated in all 4 patients, one of them developed into a T cell lymphoma. Serum EBV-DNA load was 3.26 x 10(3) copies/ml in one patient, EBER1(+) cells were detected at a frequency of 1.7% in PBMNCs from another patient; the titers of IgG to EBV-VCA were >or= 1:5120 in the rest 2 patients. All 4 patients described above were diagnosed as CAEBV infection. In conclusion, the immune-related cytopenia, macrophage activation syndrome and lymphoproliferative disorders are characteristics of CAEBV infection associated hematological disorders in these 4 children patients.

[Atypical lymphocytes]

Atypical lymphocytes or reactive are cells that become large as a result of antigen stimulation. This cells usually are associated with viral illnesses, however they can also be present as result of drug reactions, immunisations, humoral diseases and auto-immune disorders.

Safety, efficacy, and immune reconstitution after rituximab therapy in pediatric patients with chronic or refractory hematologic autoimmune cytopenias

BACKGROUND

Autoimmune hematologic cytopenias in children often require therapeutic intervention. We report a prospective pediatric multicenter trial of rituximab for refractory or steroid-dependent patients.

METHODS

Four doses of rituximab (375 mg/m(2)/dose) were administered weekly. Patients without response after three doses were offered dose escalation to 750 mg/m(2)/dose/week x 3. Safety, efficacy, and immunologic tests were evaluated after therapy.

RESULTS

Twenty-nine of 30 children (2-18 years) with thrombocytopenia (21), hemolytic anemia (6), Evans syndrome (2), and neutropenia (1) received at least four doses of rituximab. One developed anaphylaxis with the first dose. One patient was subsequently diagnosed with monosomy 7 myelodysplasia. Of 28 remaining patients, 9 received dose escalation. Responders discontinued other therapy following rituximab. The overall response rate was 72% with median follow-up of 18 months. Complete remission was observed in 14 (50%); all received four doses of rituximab. Partial remission (PR) was observed in six (22%); five had received dose escalation. Of four relapses, 4-24 months after therapy, two were retreated with rituximab and achieved second remission. No major infections were encountered. Circulating B-cells were depleted by 1 month and normalized by 1 year. IgM, Ig A, and IgG levels decreased 6, 9, and 12 months after therapy, respectively, but remained near normal range. Tetanus toxoid antibody titers remained detectable.

CONCLUSIONS

Rituximab was well tolerated, and induced sustained remissions in children with refractory immune cytopenias. Dose escalation and re-treatment after relapse elicited additional responses. Rituximab therapy should be considered prior to potential interventions with higher toxicity.