Israel Medical Association Journal

Background: Experimental and clinical protocols are being developed for the cryopreservation of human hematopoietic progenitor cells. However, the effect of these procedures on the potential for HPC[1] to repopulate bone marrow is unknown.

Objectives: To examine the effect of cryopreservation on the ability of fetal human liver HPC, which include CD34+ cells and long-term culture-initiating cells, to repopulate immunodeficient non-obese diabetic/severe combined immunodeficiency mouse bone marrow.

Methods: Groups of sublethally irradiated NOD[2]/SCID[3] mice were injected intravenously with cryopreserved or freshly isolated fetal human liver HPC.

Results: Seven weeks after transplantation, flow cytometric analysis of bone marrow samples showed that mice that received the transplanted cells (either cryopreserved or freshly isolated) demonstrated both lymphoid and myeloid differentiation as well as the retention of a significant fraction of CD34+ cells. Conclusions: Cryopreserved fetal human liver-derived HPC appear to be capable of initiating human cell engraftment in NOD/SCID mouse bone marrow and open the possibility of using cryopreserved fetal human liver HPC for gene manipulation, gene transfusion therapy, and transplantation purposes.

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[1] HPC = hematopoietic progenitor cells

[2] NOD = non-obese diabetic

[3] SCID = severe combined immunodeficiency

Background: Chronic childhood autoimmune hemolytic anemia is an uncommon disorder that is associated with significant morbidity. Treatment with high dose steroids, splenectomy and frequent blood transfusions results in a myriad of complications including growth failure, bone demineralization, Cushing’s syndrome, immunosuppression, and transfusional hemosiderosis.

Objectives: To investigate the efficacy of the monoclonal anti-CD20 antibody, rituximab, in treating children with AIHA[1].

Methods: Four children with chronic AIHA, including two with prior splenectomy, who were dependent on high dose steroids and refractory to other immunosuppressive regimens were treated with four to six weekly doses of rituximab at a dose of 375 mg/m².

Results: All four patients became transfusion-independent and were taken off prednisone completely. Adverse effects included infusion-related reactions that were mild, and infectious complications of Pneumocystis carinii pneumonia and varicella pneumonia.

Conclusions: Treatment with rituximab appears promising for refractory AIHA; it may obviate the need for prednisone and may result in sustained disease remissions in some patients.

Hemophagocytic lymphohistiocytosis is thought to occur as a primary (familial) form or secondary to infection or malignancy. Recently, several defects in genes important for immune functions were identified in patients with HLH[1]. These include mutations in perforin, the gamma common chain, the receptor for interleukin-2, Slap and purine nucleoside phosphorylase. Since abnormal function of these genes is associated with a wide clinical spectrum, HLH is probably another manifestation of immune deficiency and a thorough immune evaluation should be done in all such patients.

Intractable forms of autoimmune diseases follow a rapid course, with a significantly shortened life expectancy sometimes comparable to that of malignant diseases. Immunoablative therapy, including high dose cytotoxic agents and hematopoietic autologous stem cell rescue, was recently introduced as an aggressive approach to treat autoimmune diseases that have a rapid course and are resistant to conventional therapy. The most frequent indication for this type of treatment is multiple sclerosis, seconded by systemic sclerosis. The results of immunoablative treatment with documented responses in both diseases are encouraging. The data are mature enough to begin comparative randomized studies of immunoablative versus conventional treatment to validate the benefit of the aggressive approach. A randomized trial involving SSc[1] was recently launched (ASTIS) and a trial involving MS[2] is under preparation. Considerably less experience with immunoablative treatment has been gained in systemic lupus erythematosus, rheumatoid arthritis, and other disorders with an autoimmune pathophysiology. Autologous hematopoietic stem cell transplantation in humans offers more long-lasting immunosuppression than reeducation of lymphocytes. In fact, allogeneic transplantation may replace the whole immune system. However, this attractive approach is still associated with considerable morbidity and mortality and is not yet justified for treatment of automimmune diseases. Non-myeloablative allogeneic transplantation and sub-myeloblative high dose cyclophosphamide without stem cell support are alternative approaches that could be explored in pilot studies.

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