Hematophagic histiocytosis. A report of 23 new patients and a review of the literature

The clinical and laboratory features of 23 new patients as well as 50 previously reported patients with the syndrome of hematophagic histiocytosis are reviewed. The syndrome occurs more often in men than women but has no age predilection. Common presenting features include fever, hepatic and splenic enlargement, lymphadenopathy, and profound depression of blood counts. The clinical course is generally fulminant and may be complicated by coagulation abnormalities, hepatic dysfunction and renal failure. In the majority of patients, however, the syndrome is self-limited with resolution of the clinical and laboratory abnormalities within several weeks. Hematophagic histiocytosis generally occurs in patients who develop infections in the setting of preexisting immunologic abnormalities or neoplasms. Viral infections are most commonly involved, but virtually any other infectious agent can precipitate this syndrome. The characteristic morphologic feature of the hematophagic histiocytosis is the proliferation of mature histiocytes actively ingesting other blood cells. These hematophagic histiocytes most commonly involve the bone marrow but may also be present in the lymph nodes, spleen and liver. Other bone marrow abnormalities include hypocellularity with preservation of megakaryocytes, and myelofibrosis. The principal features of this syndrome that distinguish it from malignant histiocytosis are the cytologic maturity and degree of hematophagic activity of the histiocytes as well as its more favorable prognosis. In some patients, however, a clear distinction of malignant from reactive histiocytosis will not be possible until a clonal marker for malignant histiocytes is identified. Based in our experience, the syndrome of hematophagic histiocytosis appears to be more common than malignant histiocytosis.

c-mpl mutations are the cause of congenital amegakaryocytic thrombocytopenia

Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare disease presenting with isolated thrombocytopenia in infancy and developing into a pancytopenia in later childhood. Thrombopoietin (TPO) is the main regulator of thrombocytopoiesis and has also been demonstrated to be an important factor in early hematopoiesis. We analyzed 9 patients with CAMT for defects in TPO production and reactivity. We found high levels of TPO in the sera of all patients. However, platelets and hematopoietic progenitor cells of patients with CAMT did not show any reactivity to TPO, as measured by testing TPO-synergism to adenosine diphosphate in platelet activation or by megakaryocyte colony assays. Flow cytometric analysis revealed absent surface expression of the TPO receptor c-Mpl in 3 of 3 patients. Sequence analysis of the c-mpl gene revealed point mutations in 8 of 8 patients: We found frameshift or nonsense mutations that are predicted to result in a complete loss of c-Mpl function in 5 patients. Heterozygous or homozygous missense mutations predicted to lead to amino acid exchanges in the extracellular domain of the receptor were found in 3 other patients. The type of mutations correlated with the clinical course of the disease. We propose a defective c-Mpl expression due to c-mpl mutations as the cause for thrombocytopenia and progression into pancytopenia seen in patients with CAMT.

A phase 2 trial of combination low-dose thalidomide and prednisone for the treatment of myelofibrosis with myeloid metaplasia

Single-agent thalidomide (THAL) at "conventional" doses (> 100 mg/d) has been evaluated in myelofibrosis with myeloid metaplasia (MMM) based on its antiangiogenic properties and the prominent neoangiogenesis that occurs in MMM. THAL monotherapy at such doses produces approximately a 20% response rate in anemia but is poorly tolerated (an adverse dropout rate of > 50% in 3 months). To improve efficacy and tolerability, we prospectively treated 21 symptomatic patients (hemoglobin level < 10 g/dL or symptomatic splenomegaly) with MMM with low-dose THAL (50 mg/d) along with a 3-month oral prednisone (PRED) taper (beginning at 0.5 mg/kg/d). THAL-PRED was well tolerated in all enrolled patients, with 20 patients (95%) able to complete 3 months of treatment. An objective clinical response was demonstrated in 13 (62%) patients, all improvements in anemia. Among 10 patients who were dependent on erythrocyte transfusions, 7 (70%) improved and 4 (40%) became transfusion independent. Among 8 patients with thrombocytopenia (platelet count < 100 x 10(9)/L), 6 (75%) experienced a 50% or higher increase in their platelet count. In 4 of 21 patients (19%), spleen size decreased by more than 50%. Responses observed were mostly durable after discontinuation of the PRED. The dose of THAL in this study (50 mg/d) was better tolerated than the higher doses used in previous studies. Adverse events associated with corticosteroid therapy were mild and transient. Clinical responses did not correlate with improvements in either intramedullary fibrosis or angiogenesis. THAL-PRED is well tolerated and preliminarily appears to be a promising drug regimen for treating cytopenias in patients with MMM.

Hematologic abnormalities in the acquired immune deficiency syndrome

Blood and marrow specimens were evaluated from 12 patients with the acquired immune deficiency syndrome (AIDS). Ten patients were anemic, eight leukopenic, and three thrombocytopenic. Pancytopenia was present in two patients and subsequently developed in two others. Reticulocyte counts were not increased in the anemic patients. The most common peripheral blood abnormalities were a left shift in the granulocyte series, lymphopenia, atypical lymphocytes, and vacuolated monocytes. Marrow cellularity was increased in five patients and reduced in three. Marrow reticulin was increased in 10 patients; in three of these, marrow could not be obtained by aspiration. Plasma cells were increased in number in every marrow aspirate, and there was a left shift in the myeloid series in most. Aggregates of atypical lymphocytes or a diffuse increase in marrow lymphocytes occurred in seven patients. An increase in histiocytes was observed in seven marrow aspirates; in five of these, the histiocytes were phagocytizing red cells, white cells, and platelets. Necrosis was present in four marrow specimens. These hematologic abnormalities reflect, in part, the presence of systemic infection, inflammation, and the inanition associated with them. However, the high incidence of myelofibrosis, alterations in marrow cellularity, pancytopenia, and hematophagic histiocytosis indicates that the bone marrow is a target organ in AIDS.

Late presentation of dyskeratosis congenita as apparently acquired aplastic anaemia due to mutations in telomerase RNA

Aplastic anaemia in adults is usually acquired, but rarely constitutional types of bone marrow failure can occur late in life. We assessed two families with onset of pancytopenia in adults and detected two novel point mutations in the telomerase RNA gene (TERC) in each family. This gene is abnormal in some kindreds with dyskeratosis congenita. Individuals in our families with mutated TERC did not have physical signs of dyskeratosis congenita, and their blood counts were nearly normal, but all had severely shortened telomeres, reduced haemopoietic function, and raised serum erythropoietin and thrombopoietin. Bone marrow failure of variable severity due to dyskeratosis congenita, historically characterised by associated physical anomalies and early pancytopenia, may be present in otherwise phenotypically normal adults, and can masquerade as acquired aplastic anaemia.

Modifications of the conditioning regimen for achieving mixed chimerism and donor-specific tolerance in cynomolgus monkeys

BACKGROUND

We demonstrated previously that a nonmyeloablative preparative regimen can induce mixed chimerism and allograft tolerance in cynomolgus monkeys.

METHODS

The current studies were designed to clarify the importance and toxicity of various elements of the allotolerance conditioning regimen by: fractionating or reducing the whole-body irradiation (WBI) dosage; adding deoxyspergualine; or deleting donor bone marrow, cyclosporine, irradiation, or splenectomy.

RESULTS

Monkeys treated without donor bone marrow, cyclosporine, or irradiation did not develop chimerism or long-term allograft survival. One of three monkeys treated without splenectomy developed chimerism but died of a surgical complication. The other two did not develop chimerism and rejected by day 117. Six of six monkeys treated with 300 cGy of fractionated WBI developed chimerism. Five of these recipients had long-term graft survival. Only two of four monkeys treated with 250 cGy developed chimerism, so a 2-week course of deoxyspergualine was added. This led to chimerism in two monkeys, but one died of ureteral stenosis and the other died of allograft rejection. An unanticipated high incidence of ureteral complications felt to be secondary to rejection episodes and ischemic injury was observed in the long-term surviving animals.

CONCLUSIONS

All parameters of the original preparative regimen seem to be essential for consistent success. The degree of lymphocyte depletion was proportional to the WBI dose. Long-term graft survival was observed only in recipients achieving lymphocyte chimerism of > 1.5%. In this model, lymphocyte depletion seems to be the best predictor of chimerism, and significant lymphocyte chimerism seems to be important in achieving tolerance.

Donor lymphocyte infusion for the treatment of leukemia relapse after HLA-mismatched/haploidentical T-cell-replete hematopoietic stem cell transplantation

In this study, we tested the efficacy and safety of donor lymphocyte infusion (DLI) with granulocyte colony-stimulating factor (G-CSF) priming in patients who relapsed after haploidentical hematopoietic stem cell transplantation (HSCT). Twenty patients received DLI at a median of 177 days after HSCT. Eight patients survived in complete remission for a median of 1118 days. The 2-year probability of leukemia-free survival was 40%. Acute graft-versus-host disease (GVHD) grade 3-4 occurred in six patients after DLI. GVHD prophylaxis reduced the incidence of acute GVHD. Our primary data showed that G-CSF-primed DLI with GVHD prophylaxis was a potentially effective therapeutic option for patients who relapsed after haploidentical HSCT.

Aplastic anemia rescued by exhaustion of cytokine-secreting CD8+ T cells in persistent infection with lymphocytic choriomeningitis virus

Aplastic anemia may be associated with persistent viral infections that result from failure of the immune system to control virus. To evaluate the effects on hematopoiesis exerted by sustained viral replication in the presence of activated T cells, blood values and bone marrow (BM) function were analyzed in chronic infection with lymphocytic choriomeningitis virus (LCMV) in perforin-deficient (P0/0) mice. These mice exhibit a vigorous T cell response, but are unable to eliminate the virus. Within 14 d after infection, a progressive pancytopenia developed that eventually was lethal due to agranulocytosis and thrombocytopenia correlating with an increasing loss of morphologically differentiated, pluripotent, and committed progenitors in the BM. This hematopoietic disease caused by a noncytopathic chronic virus infection was prevented by depletion of CD8+, but not of CD4+, T cells and accelerated by increasing the frequency of LCMV-specific CD8+ T cells in T cell receptor (TCR) transgenic (tg) mice. LCMV and CD8+ T cells were found only transiently in the BM of infected wild-type mice. In contrast, increased numbers of CD8+ T cells and LCMV persisted at high levels in antigen-presenting cells of infected P0/0 and P0/0 x TCR tg mice. No cognate interaction between the TCR and hematopoietic progenitors presenting either LCMV-derived or self-antigens on the major histocompatibility complex was found, but damage to hematopoiesis was due to excessive secretion and action of tumor necrosis factor (TNF)/lymphotoxin (LT)-alpha and interferon (IFN)-gamma produced by CD8+ T cells. This was studied in double-knockout mice that were genetically deficient in perforin and TNF receptor type 1. Compared with P0/0 mice, these mice had identical T cell compartments and T cell responses to LCMV, yet they survived LCMV infection and became life-long virus carriers. The numbers of hematopoietic precursors in the BM were increased compared with P0/0 mice after LCMV infection, although transient blood disease was still noticed. This residual disease activity was found to depend on IFN-gamma-producing LCMV-specific T cells and the time point of hematopoietic recovery paralleled disappearance of these virus-specific, IFN-gamma-producing CD8+ T cells. Thus, in the absence of IFN-gamma and/or TNF/LT-alpha, exhaustion of virus-specific T cells was not hampered.

Phase I study of recombinant human interleukin-3 in patients with bone marrow failure

Interleukin-3 (IL-3) is a T-cell-derived colony-stimulating factor (CSF) whose primary targets include relatively early, multipotential, hematopoietic progenitor cells. In this trial, we treated 24 patients with recombinant human IL-3 given by a daily 4-hour intravenous infusion for 28 days. The dose levels were 30, 60, 125, 250, 500, 750, and 1,000 micrograms/m2/d. At least three patients were entered at every dose level. Each participant suffered from bone marrow failure, with the underlying diagnosis being myelodysplastic syndrome (13 patients), aplastic anemia (eight patients), or aplasia after prolonged high-dose chemotherapy (three patients) for multiple myeloma, breast cancer, or acute myelogenous leukemia. Most patients tolerated therapy well, with the most frequent side effects being low-grade fever and headaches. Hematopoietic changes included modest increases in neutrophil counts (eight patients), eosinophil counts (six patients), platelet counts (three patients), and reticulocyte counts (two patients). An increase in blasts occurred in one patient who had refractory anemia with excess blasts in transformation and was reversible once IL-3 was discontinued. In addition, one patient with chronic myelomonocytic leukemia showed an increase in monocytes (and granulocytes). Progression to acute leukemia did not occur. Pharmacokinetic analyses showed a rapid clearance with a mean half-life of 18.8 minutes at the 60 micrograms/m2/d dose, and 52.9 minutes at the 250 micrograms/m2/d dose. Serum concentrations of 10 to 20 ng/mL of IL-3 were achievable at the 250 micrograms/m2/d dose. Our observations indicate that recombinant human IL-3 can be given safely at doses of 1,000 micrograms/m2/d or less. In addition, on the basis of preclinical data and the biologic activity observed in this study, further trials of this molecule, alone and in combination with other growth factors, are warranted in patients with pancytopenia.

Acute myeloid leukemia following treatment of Hodgkin's disease: a review

Risk factors were analyzed and searched for possible predictive parameters for the development of acute myeloid leukemia in 216 reported patients previously treated for Hodgkin's disease. The distribution of histologic subtypes and the stage at diagnosis were similar to that of all patients with Hodgkin's disease. Seventy-five percent of the 216 patients in whom acute myeloid leukemia developed had received both radiotherapy and chemotherapy, 15% chemotherapy only, and 10% radiotherapy only. Of those receiving radiotherapy, 66% were given multiple courses or total nodal irradiation. Of the patients receiving chemotherapy, 77% had received more than eight months of single or combination drug therapy; only 4% had not been exposed to alkylating agents. When acute leukemia developed, 78% of the patients showed no clinical or pathologic evidence of residual Hodgkin's disease. A period of pancytopenia preceded the onset of overt leukemia in at least one-third of the patients. Complete or partial remission of the acute leukemia was achieved in 25% of the patients treated with antileukemic chemotherapy. On the basis of these findings, it is deemed advisable to reexamine the intensity of treatment presently being administered to achieve cure of Hodgkin's disease. Unnecessary or unproved programs of combined radiation therapy and chemotherapy should be avoided. An optimal balance between the risks and benefits of treatment needs to be applied.

Myelodysplastic Syndrome

During the past 15 years, important progress has been made in the understanding of the biology and prognosis of myelodysplastic syndrome (MDS). MDS is a clonal disorder characterized by ineffective hematopoiesis, which can lead to either fatal cytopenias or acute myelogenous leukemia (AML). Risk-adapted treatment strategies were established because of the high median age (60-75 years) of the MDS patients and the individual history of the disease (number of cytopenias, cytogenetic changes, transfusion requirements). Allogeneic bone marrow transplantation currently offers the only potentially curative treatment, but this form of therapy is not available for the typical MDS patient, who is >60 years of age. Therapy with erythropoietin and G-CSF has improved the quality of life of selected patients. The development of small molecules directed against specific molecular targets with minimal adverse effects is the hope for the future. Innovative uses of immunomodulatory agents and the optimizing of cytotoxic treatment should continue to help in the treatment of MDS.

Response of idiopathic hypereosinophilic syndrome to treatment with imatinib mesylate

Idiopathic hypereosinophilic syndrome (HES) is a rare hematologic disorder characterized by persistent eosinophilia with organ involvement. Patients with HES have a poor prognosis, but the disease course can be heterogeneous. Treatment of HES has included corticosteroids, chemotherapeutic agents such as cyclophosphamide, vincristine, hydroxyrea, and most recently interferon-alpha (IFN-alpha) which has shown long-term beneficial effects. We herein report on a patient with HES who had disease resistant to steroids, and chemotherapy with 2-chlorodeoxyadenosine and cytarabine, but who had a significant response after only 8 days of treatment with imatinib mesylate 100mg daily. The possible mechanism of response is discussed. This observation may lead to a better understanding of the pathophysiology of HES, and may provide a new form of effective therapy for the disease.

Myelopolyneuropathy and pancytopenia due to copper deficiency and high zinc levels of unknown origin II. The denture cream is a primary source of excessive zinc

Neurodegeneration of the central and peripheral nervous system associated with hypocupremia and hyperzincinemia has been widely recognized but the origin of high zinc remained unknown. Denture cream has been recently suggested as one possible source of zinc, but the frequency with which denture fixative alone accounts for this syndrome is unknown. We analyzed the origin of excessive zinc in eleven patients with a progressive myelopolyneuropathy and unexplained hypocupremia with hyperzincinemia. These patients had a detailed clinical assessment, determination of zinc and copper levels, and analyzed use of denture cream with the estimates of daily zinc exposure. We identified denture cream as a source of excessive zinc in 100% patients in our cohort. They all had a history of ill-fitting dentures requiring large amounts of denture cream, resulting in significant zinc exposure. Their copper and zinc normalized after stopping denture cream, further confirming that this is the source of high zinc. Inappropriate use of denture cream appears to be the sole source of excessive zinc in these patients.

Cytophagic histiocytic panniculitis with fever, cytopenia, liver failure, and terminal hemorrhagic diathesis

We have seen five adult patients with a clinical picture of recurrent histiocytic, cytophagic panniculitis, cytopenia, abnormal liver function tests, and a terminal, febrile bleeding diathesis. Originally thought to have Weber-Christian disease, these patients, we believe, represent a unique syndrome: lobular, histiocytic, cytophagic panniculitis. Erythrophagocytosis and cytophagocytosis are readily observed, but the cells do not show malignant features. Histiocytosis can be found at times in the bone marrow, lymph nodes, liver, spleen, and serosal tissues, as well as in the skin and subcutaneous tissues. The terminal hemorrhage in these patients is characterized by features of pancytopenia, liver failure, and intravascular coagulation. This disease may be separated from malignant histiocytosis by the chronic course, the primary involvement of the adipose tissue, and the benign histiocytes in the infiltrate. It has some similarities to other regional histiocytoses such as sinus histiocytosis, intestinal histiocytosis, and splenic histiocytosis.

Pancytopenia after removal of copper from total parenteral nutrition

Patients who develop cholestatic jaundice during chronic total parenteral nutrition (TPN) can develop significant hematologic complications due to hypocupremia if copper supplementation is withheld. A 36-year-old female with short bowel syndrome developed progressive liver dysfunction 6 months after initiation of TPN. Trace elements were omitted from her TPN because of cholestasis and persistent hyperbilirubinemia. Despite chronic diarrhea, absorption of some dietary copper was anticipated from her oral diet. Fifteen months later, the patient became red cell transfusion dependent, and her neutrophil and platelet counts steadily declined. After 19 months of receiving TPN without trace elements, her serum copper level was 25 microLg/dL (normal: 70 to 155 microg/dL). Provision of trace elements for 2 months was associated with increased serum copper, neutrophil and platelet counts and independence from red cell transfusions. When the serum copper level reached 186 microg/dL, copper supplementation was discontinued. Over the next 3 months, serum copper level fell to 10 microg/dL, neutrophil and platelet counts fell precipitously, and red cell transfusions were resumed. Once again, copper, neutrophil and platelet levels promptly rebounded with parenteral copper supplementation. Although anemia and neutropenia are well-recognized hematologic consequences of copper deficiency, thrombocytopenia rarely has been reported. This is the first report of pancytopenia secondary to TPN-related copper deficiency in which the association was confirmed when hypocupremia recurred.

A mouse model of lymphocyte infusion-induced bone marrow failure

OBJECTIVE

To develop a mouse model for the study of the pathophysiologic mechanism and treatment of human bone marrow (BM) failure.

MATERIALS AND METHODS

Unmanipulated B6D2F1 or CByB6F1 hybrid mice were infused with 10-40 x 10(6) lymph node (LN) cells from their C57BL/6 (B6) parent. Pancytopenia was monitored by cell counting, while marrow damage was assessed by histological staining. Destruction of BM hematopoietic progenitor/stem cells was measured by colony formation in vitro and irradiation protection in vivo. Serum interferon-gamma (IFN-gamma) concentration was measured by enzyme-linked immunosorbent assay. BM T cell Vbeta and Fas expressions were analyzed by flow cytometry. Treatment effects of immunosupressive agents cyclosporine, antithymocyte globulin (ATG), anti-IFN-gamma, and anti-tumor necrosis factor-alpha (anti-TNF-alpha) were tested.

RESULTS

Infusion of 30-40 x 10(6)B6 LN cells led to rapid development of severe pancytopenia, BM hypoplasia, and death. Affected mice had drastically reduced hematopoietic progenitor and stem cells. BM of affected mice showed lymphocyte infiltration, oligoclonal T cell expansion, and upregulated Fas expression. Serum IFN-gamma concentration increased two- to three-fold. Timed administration of cyclosporine or ATG abrogated pancytopenia. Treatment with anti-IFN-gamma antibody reliably rescued mice, and treatment with anti-TNF-alpha antibody extended animal survival significantly.

CONCLUSION

This mouse model indicates that activated lymphocytes and type I cytokines play important roles in marrow destruction in lymphocyte infusion-induced BM failure.

Viral-associated haemophagocytosis with parvovirus-B19-related pancytopenia

Viral-associated haemophagocyte syndrome in response to infection with human parvovirus B19 was seen in 2 patients with hereditary spherocytosis. Depressed reticulocyte response during acute parvovirus infection is a known cause of hypoproliferative crises in patients with reduced erythrocyte lifespan; the observation of parvovirus-associated haemophagocytosis could account for the pancytopenia that may accompany human parvovirus B19 infection.

A Phase II study of preoperative radiotherapy and concomitant weekly irinotecan in combination with protracted venous infusion 5-fluorouracil, for resectable locally advanced rectal cancer

PURPOSE

The aim of this study was to evaluate the efficacy and tolerance of preoperative chemoradiotherapy (CRT) with irinotecan (CPT-11) and 5-fluorouracil (5-FU) in patients with resectable rectal cancer.

METHODS AND MATERIALS

Patients with resectable T3-T4 rectal cancer and Eastern Cooperative Oncology Group performance status <2 were included. CPT-11 (50 mg/m(2) weekly) and 5-FU (225 mg/m(2)/day continuous infusion, 5 days/week) were concurrently administered with radiation therapy (RT) (45 Gy, 1.8 Gy/day, 5 days/week), during 5 weeks.

RESULTS

A total of 74 patients were enrolled: mean age, 59 years (20-74 years; SD, 11.7). Planned treatment was delivered to most patients (median relative dose intensity for both drugs was 100%). Grade 3/4 lymphocytopenia occurred in 35 patients (47%), neutropenia in 5 (7%), and anemia in 2 (3%). Main Grade 3 nonhematologic toxicities were diarrhea (14%), asthenia (9%), rectal mucositis (8%), and abdominal pain (8%). Of the 73 resected specimens, 13.7% (95% confidence interval [CI], 6.8-23.7) had a pathologic complete response and 49.3% (95% CI, 37.4-61.3) were downstaged. Additionally, 66.7% (95% CI, 51.1-80.0) of patients with ultrasound staged N1/N2 disease had no pathologic evidence of nodal involvement after CRT.

CONCLUSIONS

This preoperative CRT schedule has been shown to be effective and feasible in a large population of patients with resectable rectal cancer.

Bone marrow findings in systemic lupus erythematosus patients with peripheral cytopenias

We studied 21 bone marrow specimens from 21 patients with systemic lupus erythematosus (SLE) and peripheral cytopenias: anaemia (Hb < 10 g/dl), and/or leucopenia (white blood cell count < 4 x 10(9)/l), and/or thrombocytopenia (platelets < 150 x 10(9)/l). None of the patients had used immunosuppressive drugs in the 2 months before the study, and 11 (52.4%) had never used these drugs. The global and specific series cellularity, degree of fibrosis and necrosis were evaluated by bone marrow trephine; morphological abnormalities and iron stores were evaluated by cytological smears. The most important abnormalities viewed in bone marrow biopsies were: global hypocellularity (47.6%), increased reticulin proliferation (76.2%) with myelofibrosis in one patient, and necrosis (19.0%). The marrow aspirates were difficult to obtain in four patients, who showed an increased reticulin proliferation on histological analysis. Plasmocytosis was present in 26.7% of cases and in one there was a serum monoclonal component (IgG kappa). Iron stores were normal or increased in 26.7% of specimens and decreased or absent in 73.3%. The most frequent peripheral abnormality was leucopenia in 90.4% (19/21) and granulocytic hypoplasia was observed in 47.3% (9/19) of these patients. We conclude that the bone marrow may be a target organ in SLE with cytopenias.

Hematologic manifestations in homosexual men with Kaposi's sarcoma

Peripheral blood and bone marrow findings are presented for six homosexual males with Kaposi's sarcoma. Cytopenia in one or more cell lines was common in this group of patients, including two individuals with pancytopenia. Bone marrow findings in all patients, while not specific, were similar in that adequate numbers of normal appearing erythroid, myeloid, and megakaryocytic elements were present. Mild plasmacytosis as well as reticulin fiber increase were common findings. No patient, at time of study, demonstrated marrow involvement with Kaposi's sarcoma. We conclude that depression of peripheral blood counts in these patients was not due to marrow underproduction, and discuss possible mechanisms for increased blood cell destruction.

Hematologic manifestations in pediatric HIV infection: severe anemia as a prognostic factor

The hematologic profile of 100 symptomatic children infected by the human immunodeficiency virus (HIV) was evaluated and compared to HIV uninfected infants with transplacentally acquired maternal anti-HIV antibodies, and to HIV-negative infants born to i.v. drug-abusing HIV uninfected mothers. Anemia was present in 94% of HIV-infected infants and was a major predictor of disease progression. In 91% of patients having a hematocrit (HcT) less than 25%, the disease course was rapidly fatal. Leukopenia and thrombocytopenia occurred in 47 and 33% of HIV infected patients, respectively. Neutropenia was most severe in children with opportunistic infections. There was no evidence of suppression of any component of hematopoiesis by passively acquired antibodies to HIV.

Immunodeficiency and bone marrow failure with mosaic and germline TLR8 gain of function

Inborn errors of immunity (IEI) are a genetically heterogeneous group of disorders with a broad clinical spectrum. Identification of molecular and functional bases of these disorders is important for diagnosis, treatment, and an understanding of the human immune response. We identified 6 unrelated males with neutropenia, infections, lymphoproliferation, humoral immune defects, and in some cases bone marrow failure associated with 3 different variants in the X-linked gene TLR8, encoding the endosomal Toll-like receptor 8 (TLR8). Interestingly, 5 patients had somatic variants in TLR8 with <30% mosaicism, suggesting a dominant mechanism responsible for the clinical phenotype. Mosaicism was also detected in skin-derived fibroblasts in 3 patients, demonstrating that mutations were not limited to the hematopoietic compartment. All patients had refractory chronic neutropenia, and 3 patients underwent allogeneic hematopoietic cell transplantation. All variants conferred gain of function to TLR8 protein, and immune phenotyping demonstrated a proinflammatory phenotype with activated T cells and elevated serum cytokines associated with impaired B-cell maturation. Differentiation of myeloid cells from patient-derived induced pluripotent stem cells demonstrated increased responsiveness to TLR8. Together, these findings demonstrate that gain-of-function variants in TLR8 lead to a novel childhood-onset IEI with lymphoproliferation, neutropenia, infectious susceptibility, B- and T-cell defects, and in some cases, bone marrow failure. Somatic mosaicism is a prominent molecular mechanism of this new disease.

Haematological manifestations of childhood brucellosis

Very few data on the frequency and diversity of haematological abnormalities occurring in brucellosis in children have been reported. In the present study 110 children (56 boys and 54 girls; age range, 2 months to 14 years) with proven brucellosis were investigated to determine the haematological changes during the active course of this infection. Anaemia was detected in 48 (44%) patients, of whom four had evidence of haemolysis. Leukopenia occurred in 33% of the cases, with neutropenia and/or lymphopenia being the most striking features encountered. Thrombocytopenia was found in six (5%) patients and pancytopenia in 15 (14%) patients, of whom one developed disseminated intravascular coagulation. Clinically detectable bleeding occurred in five (4.5%) patients whose platelet counts were significantly low. Hypersplenism, haemophagocytosis and granulomatous lesions of the bone marrow appear to play a fundamental role in producing these abnormalities of the peripheral blood. Brucellosis may be considered in patients whose blood picture reveals haemolytic anaemia, leukopenia, thrombocytopenia or pancytopenia, particularly when the disease is epidemiologically suspected.