Systemic lupus erythematosus, thrombocytopenia, microangiopathic haemolytic anaemia and anti-CD36 antibodies [clinical conference]

Thrombocytopenia in patients with acute systemic lupus erythematosus (SLE) frequently presents the clinician with considerable diagnostic and therapeutic difficulties. In this Grand Round, we present a 48-yr- old woman with a 7 yr history of lupus, who presented with acute proliferative glomerulonephritis and nephrotic syndrome, pneumonia, profound hypocomplementaemia and a severe microangiopathic haemolytic anaemia with associated thrombocytopenia. Her thrombocytopenia proved initially refractory to conventional immunosuppressive therapy, and corticosteroids, and resolved only with plasma exchange and repeated fresh frozen plasma infusions. Serological testing revealed high-titre antinuclear antibodies (ANA) and markedly raised antibodies to double- stranded (ds) DNA, but no significant elevation in anticardiolipin antibodies. Platelet-associated IgG and IgM and antibodies to the CD36 glycoprotein antigen, expressed on platelets and endothelium, were detected in the serum. We address some of the difficult diagnostic and management issues raised by this complex patient and the possible immunopathological links between antibodies to CD36, immune-mediated red cell destruction, thrombocytopenia and thrombotic microangiopathic haemolytic anaemia.      

Relationship of the clinical response and binding of recombinant interferon alpha in patients with lymphoproliferative diseases

Patients with hairy cell leukemia (HCL) and chronic lymphocytic leukemia (CLL) were treated with recombinant interferon alpha A (rIFN- alpha A). The binding of iodinated recombinant interferon-alpha to baseline samples of peripheral blood mononuclear cells (PBMCs) from the leukemia patients was compared with clinical responsiveness to rIFN- alpha A. HCL patients (8/10) responded to rIFN-alpha A therapy, whereas none (0/10) of the CLL patients studied responded. The PBMCs from the eight responsive HCL patients bound approximately twice as much iodinated interferon as the PBMCs from nonresponsive CLL patients. This difference was due to more high-affinity receptors per cell with no difference in the affinity of the interferon-receptor interaction. However, because PBMCs from HCL patients were larger than PBMCs from CLL patients, the cell surface receptor density was similar. The leukemic cells from one of the two nonresponsive HCL patients bound iodinated interferon similarly to the cells from the responsive HCL patients, whereas the leukemic cells from the other nonresponsive HCL patient bound considerably less. The rapidity of response of the HCL patients did not correlate with the level of binding of iodinated interferon. Our results suggest that the absolute number of interferon receptors per cell may be only one of several important parameters in the response to rIFN-alpha A therapy, and that the responsiveness of a particular lymphoproliferative disease or a particular patient to rIFN- alpha A therapy cannot be predicted or explained solely by the degree of interaction between IFN and its cell surface receptor.     

The activation of the contact phase of coagulation by physiologic surfaces in plasma: the effect of large negatively charged liposomal vesicles

The endogenous, negatively charged surface that induces activation of the contact coagulation factors was investigated in plasmas taken from women in late pregnancy and control subjects of child-bearing age. The plasmas from the two groups of subjects were incubated at 4 degrees C for 24 hours either in plastic or in glass tubes and the factor VII coagulant activity (VIIc) was assayed in the treated plasmas. The activation of factor VII under these conditions involves the generation of enzymes derived from factor XII (XIIa). The contact surface is rate- limiting for the activation of factor VII in the plasmas in both groups of subjects and can be supplemented by large multilamellar liposomal vesicles carrying the appropriate density of negative charge. The size of these vesicles is within the range of sizes of the large lipoprotein particles (chylomicrons, very low and intermediate-density lipoproteins). The relationship between the density of negative charge on the liposomal vesicles and VIIc was similar in the late pregnancy and the control plasmas incubated in plastic tubes. At a saturating density of negative charge the observed relative VIIc was similar in both sets of plasmas. The incubation of late pregnancy or control plasma in plastic tubes in the presence of sodium stearate caused VIIc to increase with increasing concentration of the added fatty acid. These results suggest that large lipoprotein particles carrying the appropriate free fatty acid at a sufficient density of negative charge could provide the contact surface that induces the generation of factor XIIa and the subsequent activation of factor VII. Moreover, plasmas from women in late pregnancy have a higher concentration of potential surface and a higher density of negative charge than the plasmas from nonpregnant women.     

Role of the B domain for factor VIII and factor V expression and function

Factor V and factor VIII are homologous cofactors in the blood coagulation cascade that have the domain structure A1-A2-B-A3-C1-C2, of which the B domain has extensively diverged. In transfected COS-1 monkey cells, expression of factor VIII is approximately 10-fold less efficient than that of factor V, primarily because of inefficient protein secretion and, to a lesser extent, reduced mRNA expression. To study the functional significance and effect of the B domain on expression and activity, chimeric cDNAs were constructed in which the B domains of factor V and factor VIII were exchanged. Expression of a factor VIII chimera harboring the B-domain of factor V yielded a fully functional factor VIII molecule that was expressed twofold more efficiently than wild-type factor VIII because of increased mRNA expression. Thus, sequences within the factor VIII B domain were not responsible for the inefficient secretion of factor VIII compared with factor V. Expression of a factor V chimera harboring the B domain of factor VIII was slightly reduced compared with wild-type factor V, although the secreted molecule had significantly reduced procoagulant activity correlating with dissociated heavy and light chains and resistance to thrombin activation. Interestingly, the factor V chimera containing the factor VIII B domain was efficiently activated by Russell's viper venum (RVV). A factor V B domain deletion (residues 710- 1545) molecule also exhibited significantly reduced procoagulant activity caused by resistance to thrombin cleavage and activation, although this molecule was activatable by RVV. These results show that, in contrast to factor VIII, thrombin activation of factor V requires sequences within the B domain. In addition, thrombin activation of factor V occurs through a different mechanism than activation by RVV.     

Reduction of serum matrix metalloproteinase 1 and matrix metalloproteinase 3 in rheumatoid arthritis patients following anti- tumour necrosis factor-alpha (cA2) therapy

Matrix metalloproteinase (MMP)-1 and MMP-3 levels were measured in serum samples from rheumatoid arthritis (RA) patients undergoing a double-blinded placebo-controlled trial with the chimaeric anti-tumour necrosis factor (TNF)-alpha antibody cA2. Both MMP-1 (P < 0.015), but to a larger extent MMP-3 (P < 0.001) levels were elevated in all RA patients prior to the commencement of the trial compared with normal control sera. Following cA2 therapy, MMP-1 and MMP-3 levels were assessed in the placebo, and 1 and 10 mg/kg cA2-treated groups at 7, 14, 21 and 28 days. In both the 1 and the 10 mg/kg cA2-treated groups, a significant decrease in serum MMP-3 levels at all time points was observed, reducing maximally to 41% of pre-infusion values at day 7. MMP-1 levels were also reduced, but less dramatically than MMP-3, to 85% of pre-infusion values after 14 days in the 10 mg/kg cA2 treated group. In a separate non-placebo-controlled study, we also evaluated the tissue inhibitor of metalloproteinase (TIMP)-1 levels in plasma following cA2 infusion. Pre-infusion TIMP-1 levels were above the normal control range, but were significantly reduced (P < 0.035) 14 days after infusion to 72% of pre-infusion values. This study confirms previous reports that MMP-3 levels are elevated and correlate with measures of inflammation in RA, and furthermore demonstrate that serum MMP-3 and MMP-1 levels are downmodulated following anti-TNF-alpha antibody therapy. Whilst serum MMP-3 levels correlated with C-reactive protein (CRP) both prior to and following anti-TNF-alpha antibody therapy, it remains to be demonstrated that serum MMP-3 and/or MMP-1 levels reflect the cartilage and bone resorptive processes which are evident in this disease.      

Differentiation of natural killer (NK) cells from human primitive marrow progenitors in a stroma-based long-term culture system: identification of a CD34+7+ NK progenitor

We have recently described a marrow stroma-dependent long-term culture system that supports differentiation of CD34+ human marrow primitive progenitors into natural killer (NK) cells. We postulate that CD7 expression may be an early event in commitment of hematopoietic progenitors to the NK lineage. Here we compare the characteristics of CD34+7- and CD34+7+ marrow cells cultivated in the stroma-based NK culture system. These CD34+ populations were further compared with a marrow derived, more committed, CD34-7+ progenitor to emphasize the continuum of NK development and to highlight differences between progenitors in our assays. No progenitor proliferated when plated in media without stroma, underscoring the importance of stroma in NK differentiation. Plating progenitor populations in interleukin-2 containing media directly on preestablished, allogeneic, irradiated marrow stroma for 5 weeks resulted in CD56+CD3- NK cells; however, characteristics of the cultured populations differed. Fold expansion and cloning efficiency of the CD34+7+ population, determined by a functional limiting dilution assay was significantly higher than of the CD34+7- or CD34+7+ populations. This suggests that the CD34+7+ population is highly enriched for an NK progenitor and a possible intermediate in NK lineage differentiation. Further dividing the CD34+7+ population by the relative fluorescence of CD7 into CD34+7+dim and CD34+7+bright populations showed that the CD34+7+bright population exhibited a significantly higher cloning frequency than parallel experiments with CD34+7+dim cells (11.8% +/- 2.4% v 2.4% +/- 0.7%, n = 6; P = .005). Plating of the more primitive CD34+7- population in a transwell system (which separates progenitors from stroma by a microporous membrane) prevents differentiation into NK cells. In contrast, plating of CD34+7+ progenitors in transwells resulted in generation of NK cells. These data suggest that primitive, but not more mature NK progenitors may require direct contact with stroma for the initial differentiation steps. Finally, differentiation of the NK progenitors in this stroma-dependent model results in expression of CD2 not present on any of the starting populations. This observation suggests that marrow stroma can stimulate CD2 expression on NK progenitors in a previously undescribed fashion that may be analogous to the thymic effect on CD2 expression in immature T lymphocytes. These observations identify early steps in the commitment of primitive marrow CD34+ hematopoietic progenitors to a lymphoid lineage and underscore the importance of coexpression of CD7 with CD34 as an early lymphoid commitment characteristic and direct progenitor-stroma interactions in this process.     

Identification of the molecular defect in the erythrocyte membrane skeleton of some kindreds with hereditary spherocytosis

We have localized the molecular alteration in the membrane skeleton of two of four kindreds with hereditary spherocytosis (HS) to an alteration in the spectrin-protein-4.1 interaction due to a defective spectrin molecule. The defective spectrin-protein-4.1 interaction in these kindreds (referred to as type I HS) leads to a weakened spectrin- protein-4.1-actin ternary complex, which in turn may lead to the friable membrane skeleton and suggested membrane instability related to this disorder. Type I HS spectrin binds approximately 63% as much protein-4.1 as normal spectrin (with equal affinity). This defect does not correlate with splenic function or erythrocyte age in the circulation. However, the approximately 37% reduction in binding of protein-4.1 to HS spectrin approaches the theoretical value of 50% expected in this autosomal dominant disorder. All other type I membrane skeletal interactions (spectrin-syndein, spectrin heterodimer- heterodimer, syndein-band-3) were found to be normal. It would appear therefore that the defective HS spectrin-protein-4.1 interaction in type I hereditary spherocytosis may be the primary molecular defect rather than a secondary phenomena.     

Recombinant rat stem cell factor synergizes with recombinant human granulocyte colony-stimulating factor in vivo in mice to mobilize peripheral blood progenitor cells that have enhanced repopulating potential

Splenectomized mice treated for 7 days with pegylated recombinant rat stem cell factor (rrSCF-PEG) showed a dose-dependent increase in peripheral blood progenitor cells (PBPC) that have enhanced in vivo repopulating potential. A dose of rrSCF-PEG at 25 micrograms/kg/d for 7 days produced no significant increase in PBPC. However, when this dose of rrSCF-PEG was combined with an optimal dose of recombinant human granulocyte colony-stimulating factor (rhG-CSF; 200 micrograms/kg/d), a synergistic increase in PBPC was observed. Compared with treatment with rhG-CSF alone, the combination of rrSCF-PEG plus rhG-CSF resulted in a synergistic increase in peripheral white blood cells, in the incidence and absolute numbers of PBPC, and in the incidence and absolute numbers of circulating cells with in vivo repopulating potential. These data suggest that low doses of SCF, which would have minimal, if any, effects in vivo, can synergize with optimal doses of rhG-CSF to enhance the mobilization of PBPC stimulated by rhG-CSF alone.     

The effects of vitamin D binding protein-macrophage activating factor and colony-stimulating factor-1 on hematopoietic cells in normal and osteopetrotic rats

Osteopetrosis is a heterogeneous group of bone disorders characterized by the failure of osteoclasts to resorb bone and by several immunological defects including macrophage dysfunction. Two compounds, colony-stimulating factor-1 (CSF-1) and vitamin D-binding protein- macrophage activating factor (DBP-MAF) were used in the present study to evaluate their effects on the peritoneal population of cells and on cells within the bone marrow microenvironment in normal and incisors absent (ia) osteopetrotic rats. Previous studies in this laboratory have demonstrated that administration of DBP-MAF to newborn ia animals results in a substantial increase in bone marrow cavity size due to upregulated osteoclast function. To study the effects of these compounds on the macrophage/osteoclast precursors, DBP-MAF, CSF-1, and the combination of these compounds were given to newborn ia and normal littermate animals. Both the normal and mutant phenotypes responded similarly when treated with these compounds. Rats exhibited a profound shift toward the macrophage lineage from the neutrophil lineage when compared with vehicle-treated control animals after treatment with these compounds. In the in vivo peritoneal lavage study, animals received injections of CSF-1, DBP-MAF or DBP-MAF/CSF-1 over a 4-week period. The various types of cells in the peritoneal cavity were then enumerated. The in vitro study consisted of cells isolated from the bone marrow microenvironment and cultured on feeder layers of CSF-1, DBP-MAF, or DBP-MAF/CSF-1 for colony enumeration. The increase in macrophage numbers at the expense of neutrophil numbers could be seen in both the in vivo and in vitro experiments. The macrophage/osteoclast and neutrophil lineages have a common precursor, the granulocyte/macrophage colony-forming cell (GM-CFC). With the addition of CSF-1, the GM-CFC precursor may be induced into the macrophage/osteoclast lineage rather than the granulocyte lineage. This increased pool of cells in the macrophage/osteoclast lineage can be functionally upregulated with the subsequent addition of DBP-MAF to perform the activities of phagocytosis and bone resorption. The in vitro data also showed that DBP-MAF did not support colony development as in CSF-1 or the combination treatment. The recruitment and activation of cells into the macrophage/ osteoclast lineage may help to correct the bone and immune defects found in diseases demonstrating a significant lack of myeloid cells, as well as neutrophilia disorders and the disease, osteopetrosis.     

Prague women's drinking before and after the 'velvet revolution' of 1989: a longitudinal study

Results are presented of a follow-up study in which a representative sample of 608 Prague women aged 20–49 years in 1987 at first interview was re-interviewed in 1992 3 years after the revolution that ended the 41 years of the Communist era in Czechoslovakia. The average yearly consumption of alcohol in the followed-up female sample increased between 1987–92 from a reported 3.6 litres to 4.8 litres. The percentage of heavier drinkers (with average daily consumption of over 20 g alcohol) increased from 7.2% to 14.0%. The women expressed increased tolerance of drunkenness in their attitudes to drinking. The consumption increase was mainly due to increased drinking frequency of spirits and to increased quantity of beer consumed per occasion. The consumption increase was largest in women working as free-lance and the newly emerging self-employed women; economically inactive women did not increase their consumption. Women who reported a positive impact of the socio-political changes on their personal lives and an expansion of social contacts also reported larger than average consumption increases. A coincidence of stressful, possibly self-inflicted, life events and increased alcohol use was observed and interpreted as probably a two-way influence.