The demarcation membrane system of the megakaryocyte: a misnomer?

The concept that the demarcation membrane system delineates platelets within the cytoplasm of megakaryocytes has been examined. In short-term culture of mouse bone marrow, mature megakaryocytes extended long, attenuated processes that were found by electron microscopy to have a limited amount of invaginated membrane. When such megakaryocytes were exposed to microtubule depolymerizing agents, the attenuated processes retracted, became thicker, and an extensive demarcation membrane reappeared. It is suggested from the results that the demarcation membrane system functions to provide a membrane reserve that undergoes evagination during the formation of attenuated processes and thereby envelops putative platelets, rather than to demarcate platelets in the maturing megakaryocyte. The term "invaginated membrane system" is considered more appropriate than "demarcation membrane system."     

The two-year follow-up of a randomized comparison of in-patient multidisciplinary team care and routine out-patient care for active rheumatoid arthritis

The long-term effects of a period of 11 days of in-patient multidisciplinary team care were compared with routine out-patient care in 80 patients with active rheumatoid arthritis (RA). Endpoint measures included swollen and tender joint counts, the patient's assessment of pain, the patient's and the physician's assessments of disease activity, the ESR and the Health Assessment Questionnaire (HAQ). Two years after hospitalization, all 39 patients randomized to the in- patient group and 39 out of 41 patients randomized to the out-patient group were evaluable. At 2 yr, in the in-patient group the improvement according to mean changes from baseline was greater than that in the out-patient group for all endpoint measures except for the HAQ score, the differences not reaching statistical significance. Averaged over the time points 2, 52 and 104 weeks, the improvement was significantly greater in the in-patient group than in the out-patient group, except for the ESR and HAQ score. In conclusion, a short period of in-patient multidisciplinary team care has a beneficial effect on disease activity over a period of 2 yr and should be considered as a useful treatment modality in patients with active RA.      

Intensive leukapheresis as initial therapy for chronic granulocytic leukemia

Intensive leukapheresis has been used as the initial treatment of chronic granulocytic leukemia (CGL) in six patients. The number of leukaphereses ranged from 3 in 7 days to 13 in 39 days (mean, 8 in 22 days). The procedures were well tolerated, and in all patients there was improvement in hematologic values, in most cases with considerable reduction in the peripheral leukocytosis and thrombocytosis and in the proportion of immature granulocytic cells in the circulation. Splenomegaly decreased considerably in the four patients who had more than four leukaphereses. Symptoms of sweating, malaise, and pain due to splenomegaly were rapidly relieved. Problems due to hyperuricemia did not occur, but four patients required blood transfusions for correction of anemia. This method of initial treatment of CGL appears to give more rapid relief of symptoms than does conventional chemotherapy; it incurs no risk of hyperuricemia and lessens that associated with thrombocytosis. In addition, large quantities of granulocyte-rich plasma are made available for the treatment of infections in neutropenic patients. Intensive leukapheresis deserves more widespread evaluation as the initial treatment of CGL.     

BCL-2 but not its Epstein-Barr virus-encoded homologue, BHRF1, is commonly expressed in posttransplantation lymphoproliferative disorders [see comments]

Posttransplantation lymphoproliferative disease (PTLD) is virtually always associated with Epstein-Barr virus (EBV) infection. BCL-2 and other proteins that confer resistance to apoptosis have been implicated in the pathogenesis of a variety of malignancies including lymphomas. One EBV protein, BHRF1, is a homologue of BCL-2, whereas another, the latency membrane protein 1 (LMP-1), upregulates BCL-2 expression in vitro. In the present study, we used immunohistochemistry to study the expression of these viral and cellular proteins as well as a variety of other EBV-encoded proteins in PTLD. BHRF1 was not detected in any PTLD specimen, whereas BCL-2 was shown in 12 of 17 lesions examined. With one exception, all LMP1-positive cases also expressed BCL-2 and the absence of LMP1 was always associated with a lack of BCL-2 expression. The results do not support a role for the EBV homologue of BCL-2 in PTLD, but they do support a role for viral induction of BCL-2 expression.     

An experimental model of idiopathic pneumonia syndrome after bone marrow transplantation: I. The roles of minor H antigens and endotoxin

Idiopathic pneumonia syndrome (IPS) refers to diffuse, non-infectious pneumonia that occurs after allogeneic bone marrow transplantation (BMT). We have developed a model of IPS using a well-characterized murine BMT system (B10.BR-->CBA) in which lung injury after BMT can be induced by minor histocompatibility (H) antigenic differences between donor and host. Lung pathology and broncho-alveolar lavage (BAL) fluid were analyzed in transplant recipients before and after both syngeneic and allogeneic BMT. At 2 weeks after BMT, no specific pathologic abnormalities were noted; at 6 weeks, both pneumonitis and mononuclear cell infiltration around vessels and bronchioles were observed only in mice receiving allogeneic BMT. This injury was associated with elevated BAL fluid levels of endotoxin (lipopolysaccharide [LPS]), neutrophils, and tumor necrosis factor alpha. No pathologic organisms were isolated from the respiratory tract of any animal. We also tested the role of endotoxin in the development of this injury. Injection of LPS 6 weeks after transplantation caused profound lung injury only in mice with moderate graft-versus-host disease; dramatic increases in BAL neutrophils and tumor necrosis factor alpha were observed, with alveolar hemorrhage occurring in 4 of 12 of these mice but in no other group. We conclude that (1) this murine BMT system is a potentially useful model of clinical IPS; (2) minor H differences between donor and recipient can be important stimuli in the pathogenesis of IPS; and (3) endotoxin in BAL fluid is associated with lung injury, and excess endotoxin can cause the development of alveolar hemorrhage in this model.     

Complete recovery of hemopoiesis following bone marrow transplant in a patient with unresponsive congenital hypoplastic anemia (Blackfan- Diamond syndrome)

Allogeneic bone marrow transplantation (BMT) was carried out on a 5- year-old boy with congenital hypoplastic anemia (CHA), who did not respond to corticosteroids and who was displaying signs of progressive hemosiderosis. Pretransplant preparation had to be modified because respiratory failure and cerebral edema supervened. This preparatory regimen consisted of busulfan (2 mg/kg for four days), cyclophosphamide (50 mg/kg for one day), and total body irradiation (750 rad). Hemopoiesis was completely restored and is still maintained 650 days after transplantation. This is the second published report on the use of BMT to treat a patient with CHA, and it is the first time it has resulted in long-term survival. BMT should be considered for patients with CHA who do not respond to corticosteroids.     

Bone marrow transplantation for paroxysmal nocturnal hemoglobinuria: eradication of the PNH clone and documentation of complete lymphohematopoietic engraftment

Paroxysmal nocturnal hemoglobinuria (PNH) involves the proliferation of an abnormal and possibly premalignant hematopoietic stem cell. Successful treatment of PNH by marrow grafting requires that the PNH clone be eradicated by the pretransplant conditioning regimen. Four patients with PNH-associated marrow aplasia were transplanted with marrow from their HLA-matched, MLR-nonreactive siblings. Three patients were conditioned with cyclophosphamide, procarbazine, and antithymocyte serum (CTX/PCZ/ATS), and one was conditioned with busulfan/CTX/PCZ/ATS. Persistent complete engraftment of myeloid, lymphoid, and erythroid cell lines was demonstrated in all four patients by DNA sequence polymorphism analysis or cytogenetics, and RBC typing. There was no recurrence of the abnormal clone of cells for up to five years after transplantation despite the use of a conditioning regimen in three of them, which is not usually associated with permanent marrow aplasia. Bone marrow transplantation is a curative therapy in patients whose illness is severe enough to warrant the risk.     

An evaluation of crossmatching, HLA, and ABO matching for platelet transfusions to refractory patients

Refractoriness occurs in many patients receiving multiple platelet transfusions. We used a sensitive ELISA assay to assess the utility of crossmatching HLA-A,B matched single donor platelets in 51 consecutive, typical refractory patients. Of the 222 transfusions evaluated at 1 to 4 hours posttransfusion, only 17 of 54 (31%) with positive crossmatches had corrected platelet count increments of greater than or equal to 7,500/microL. In contrast, 95 of 168 (57%) of those with negative crossmatches had such increments (P less than .001). Regardless of the results of the crossmatch, HLA-A,B, and ABO matching had independent influences on transfusion outcome. The median corrected 1- to 4-hour increment for crossmatch negative transfusions was 13,300/microL for A/BU grade matches, 9,700 for BX, and 7,800 for C. Increments were 10,000/microL for ABO-identical transfusions and 5,900 for transfusions of platelets ABO incompatible with the recipient's plasma antibodies. When the donor platelets were ABO compatible, but the donor plasma contained ABO antibodies to the recipient's platelets, the increment was intermediate (8,200/microL). The most important factor in predicting platelet survival was the crossmatch, followed by HLA-A,B and ABO, each having independent predictive value. These data demonstrate that the predictive value of a negative crossmatch may be considerably less than that reported in previous studies with stable, less ill patients. In typical refractory patients, there appear to be mechanisms of platelet destruction that are related to HLA-A,B and ABO but are not detected with current crossmatch methods. We hypothesize that soluble plasma HLA-A,B and ABO antigens contribute to the destruction of donor and sometimes recipient platelets by an immune complex or other "innocent bystander" mechanism. With our crossmatching technique, HLA-A,B and ABO match grades remain relevant to platelet transfusion therapy in some refractory patients.     

Adjuvant immunotoxin therapy with anti-B4-blocked ricin after autologous bone marrow transplantation for patients with B-cell non- Hodgkin's lymphoma

Anti-B-blocked ricin (anti-B4-bR) combines the specificity of the anti- B4 (CD19) monoclonal antibody with the protein toxin "blocked ricin." In blocked ricin, affinity ligands are attached to the ricin B-chain to attenuate its lectin binding capacity. In a phase I trial, Anti-B4-bR was administered by 7-day continuous infusion to 12 patients in complete remission after autologous bone marrow transplantation (ABMT) for relapsed B-cell non-Hodgkin's lymphoma (NHL). Patients were treated at 20, 40, and 50 micrograms/kg/d for 7 days. Potentially therapeutic serum levels could be sustained for 3 to 4 days. The maximum tolerated dose was 40 micrograms/kg/d for 7 days (total 280 micrograms/kg). The dose-limiting toxicities were reversible grade IV thrombocytopenia and elevation of hepatic transaminases. Mild capillary leak syndrome was manifested by hypoalbuminemia, peripheral edema (4 patients), and dyspnea (1 patient). Anti-immunotoxin antibodies developed in 7 patients. Eleven patients remain in complete remission between 13 and 26 months post-ABMT (median 17 months). These results show that Anti-B4- bR can be administered with tolerable, reversible toxicities to patients with B-cell NHL in complete remission following ABMT.