The secretion of plasminogen activators by human myeloid leukemic cells in vitro

Peripheral blood cell preparation from 23 normal subjects and 72 patients with acute and 32 patients with chronic myeloid leukemia were cultured in vitro and released plasminogen activators were analyzed. The quantity of plasminogen activator secreted by leukemic cells varied widely and could not be correlated with the clinical severity of the disease. Immunochemical and electrophoretic techniques have been used to show that normal peripheral blood granulocytes released exclusively urokinase-like plasminogen activator, whereas leukemic cells secreted either urokinase or a tissue activator-like enzyme. The molecular species of enzyme released by acute myeloid leukemic cells may serve as a diagnostic marker of relevance to the management of this disease, since patients with acute myeloid leukemia whose cells released only tissue plasminogen activator did not respond to combination chemotherapy. Tissue plasminogen activators released by leukemic cells may display an unusual electrophoretic pattern that resembles that shown by urokinase. Immunochemical procedures are therefore essential for the correct identification of these enzymes.     

P-selectin glycoprotein ligand-1 (PSGL-1) is a ligand for L-selectin in neutrophil aggregation

In inflammation, activated neutrophils adhere to endothelial cells and aggregate with one another. While beta 2-integrin and L-selectin are essential for aggregation, their ligands remain to be identified. We have previously shown that L-selectin mediates a carbohydrate-dependent interaction in aggregation (Simon et al: J Immunol 149:2765, 1992; Rochon et al: J Immunol 152:1385, 1994). We have suggested that the L- selectin counter-structure is a mucinlike protein and proposed that aggregation occurs through a two-step process involving L-selectin, beta 2-integrin, and their distinct counter-structures (Bennett et al: J Leuk Biol 58:510, 1995). A candidate ligand for L-selectin is P- selectin glycoprotein ligand-1 (PSGL-1), a mucinlike protein on neutrophils that binds P-and E-selectin. Using flow cytometry we show that the number and size of neutrophil aggregates is reduced with Fab fragments of PL1, an anti-PSGL-1 monoclonal antibody that blocks the interaction between P-selectin and PSGL-1 (Moore et al: J Cell Biol 128:661, 1995). In addition, monoclonal antibodies to L-selectin and PSGL-1 were used simultaneously to modulate the availability of these adhesion molecules on individual cell populations. The inhibition of aggregation by these antibodies is consistent with L-selectin and PSGL- 1 being counter-structures. We suggest that L-selectin and PSGL-1 support a collisional cell-cell interaction that represents the first step in neutrophil aggregation.     

Sleep apnoea caused by rheumatoid arthritis

Sleep apnoea syndrome (SAS) is a rarely documented, but possibly lethal, complication of the instability of the cervical spine in rheumatoid arthritis. Five patients with SAS of a central or peripheral origin are presented, and the problems of recognizing and diagnosing the syndrome are discussed. We hope that clinicians will become more aware of the existence and the different aetiologies of SAS, thus improving early recognition and appropriate treatment. Adequate treatment has proven to increase survival in peripheral SAS and seems to be successful in doing so in central SAS.      

Comparative evidence for a link between Peyer's patch development and susceptibility to transmissible spongiform encephalopathies

Background  

Epidemiological analyses indicate that the age distribution of natural cases of transmissible spongiform encephalopathies (TSEs) reflect age-related risk of infection, however, the underlying mechanisms remain poorly understood. Using a comparative approach, we tested the hypothesis that, there is a significant correlation between risk of infection for scrapie, bovine spongiform encephalopathy (BSE) and variant CJD (vCJD), and the development of lymphoid tissue in the gut.     

Donation reactions among autologous donors

Studies of risk factors associated with reactions among autologous blood donors have been limited. Therefore, 2091 autologous and 4737 homologous donations were examined. Donors at greatest risk for reaction were autologous donors who had reactions at first donation; among 45 who made repeat donations for the same surgery, 17 (38%) had repeat reactions. The group least likely to experience reactions were the autologous donors greater than or equal to 66 years old; they experienced a 1.9 greater than or equal to percent (6/310) incidence of reactions. More reactions were seen in both autologous and homologous donors in the categories of first-time donor, female gender, decreasing age, and lower weight. Multiple logistic regression analysis showed that all of these variables were independent predictors of donor reaction, with first-time donation (odds ratio, 2.4) and female gender (odds ratio, 1.9) being the strongest predictors of reaction. Donor room personnel should be alerted that autologous donors who react at first donation are very likely to react at subsequent donations. Contrary to common concern, elderly autologous donors are least likely to have reactions.     

A model to determine required pool size for HLA-typed community donor apheresis programs

Community donor plateletpheresis programs must have adequate numbers of HLA-typed donors to support the transfusion needs of alloimmunized patients, and donor pool size calculations should reflect the fact that each patient needs more than one donor to provide his or her support. The average number of donors needed to provide a patient's support was estimated as a function of donor usage and commitment. A model was developed for determining an appropriate size of the donor pool for a community donor plateletpheresis program that would incorporate the average number of donors needed per patient, the level of HLA compatibility to be maintained between patient and donor, and the frequencies of patient and donor HLA phenotypes. A database of 4338 plateletpheresis transfusions given to 591 patients from a pool of up to 870 community donors over a 3-year period was analyzed retrospectively to validate the estimates of the average number of donors needed to support a patient, which ranged from 4 to 33 donors. This database was also used to illustrate the application of the pool size determination model. Model results suggest that plateletpheresis donor pools of 1000 to 3000 donors are capable of meeting the transfusion needs of most patients at an HLA-match grade of B2 or better.