Transverse myelopathy in systemic lupus erythematosus: an analysis of 14 cases and review of the literature.

OBJECTIVE: To give a comprehensive review of transverse myelopathy (TM), a rare but serious condition reported in 1-2% of patients with systemic lupus erythematosus (SLE). METHODS: 14 patients with SLE and TM were evaluated and 91 additional cases published in the English and German literature reviewed. RESULTS: TM presented either as the initial manifestation or within five years of the diagnosis of SLE. Most patients presented with a detectable sensory deficit at the thoracic level. In our 14 patients, 22% of the patients showed complete neurological recovery, whereas in the total patient population of 105 (our cases plus those reviewed in the literature), complete recovery was observed in 50%, partial recovery in 29% and no improvement or deterioration in 21%. Treatment with intravenous methylprednisolone followed by cyclophosphamide seemed to be most effective. Seventy per cent of the total patient population had abnormal magnetic resonance imaging findings. In our group of 14 patients, those with higher disease activity (measured by the SLAM) at onset of TM were treated more aggressively (for example, with plasmapheresis and intravenous pulse cyclophosphamide). TM in our patients was associated with antiphospholipid antibodies in 43% of the cases as compared with 64% of the total patient population. Optic neuritis occurred in 48% of the total patient population with SLE and TM, suggesting an association. CONCLUSIONS: TM in SLE is a poorly understood entity. Outcome might be more favourable than previously suggested. There is an association of TM with antiphospholipid antibodies in SLE patients. Treatment including intravenous cyclophosphamide may improve the final outcome. This report emphasises the need for multicentre trials to establish guidelines for optimal treatment.

Deglycosylation of serum vitamin D3-binding protein by alpha-N-acetylgalactosaminidase detected in the plasma of patients with systemic lupus erythematosus.

A serum glycoprotein, Gc protein (vitamin D3-binding protein), can be converted by beta-galactosidase of B cells and sialidase of T cells to a potent macrophage-activating factor (MAF), a protein with N-acetylgalactosamine as the remaining sugar moiety. Thus, Gc protein is the precursor for MAF. Treatment of Gc protein with immobilized beta-galactosidase and sialidase generates a remarkably high titered macrophage-activating factor (GcMAF). When peripheral blood monocytes/ macrophages (designated macrophages) of 33 systemic lupus erythematosus patients were incubated with GcMAF (100 pg/ml), the macrophages of all patients were activated as determined by superoxide generation. However, the precursor activity of patient plasma Gc protein was lost or reduced in these patients. Loss of the precursor activity was the result of deglycosylation of plasma Gc protein by alpha-N-acetylgalactosaminidase activity found in the patient plasma. Levels of plasma alpha-N-acetylgalactosaminidase activity in individual patients had an inverse correlation with the MAF precursor activity of their plasma Gc protein. Deglycosylated Gc protein cannot be converted to macro-phage-activating factor. The resulting defect in macro-phage activation may lead to an inability to clear pathogenic immune complexes. Thus, elevated plasma alpha-N-acetylgalactosaminidase activity resulting in the loss of MAF precursor activity and reduced macro-phage activity may play a role in the pathogenesis of systemic lupus erythematosus.

Transmembrane potential responses during HL-60 promyelocyte differentiation.

Myeloid cells, including granulocytes and monocyte/macrophages, are important in disease-associated inflammatory reactions. These cells come from a common progenitor, the promyelocyte. The human promyelocytic cell line, HL-60, can be induced to terminally differentiate into granulocytes or monocyte/ macrophages in a controlled fashion providing a model to study various aspects of myelomonocytic differentiation. The expression of several ion channels is controlled in HL-60 cells in a differentiation specific pattern. The purpose of this study was to determine if lineage-specific ion channel expression during HL-60 differentiation resulted in differences in functional responses to external stimuli. This was investigated by examining transmembrane potential responses in HL-60 promyelocytes, HL-60-derived polymorphonuclear cells (PMNs), and monocytes to various stimuli using the transmembrane potential sensitive dye, diSBAC2-(3). Exposure of HL-60 promyelocytes to ionomycin or ATP produced a membrane hyperpolarization. Studies using ion substitutions and ion channel blockers indicate that the hyperpolarization was mediated by KCa channels. During HL-60 promyelocyte differentiation to PMNs, the membrane potential response to ionomycin and ATP shifted from a hyperpolarization to a depolarization over 7 days. Conversely, HL-60-derived monocytes exhibited a membrane hyperpolarization in response to ionomycin and ATP. HL-60-derived monocytes also exhibit a Cl- conductance specifically induced by ATP. Lineage-specific expression of ion channels during HL-60 cell differentiation is important in determining the transmembrane potential response of these cells. This may be translated into functional responses of various myelomonocytic cells during disease-associated inflammatory reactions.

Mitogen-activated Ca++ channels in human B lymphocytes.

Two complementary experimental methods have been used to examine mitogen-induced transmembrane conductances in human B cells using the Daudi cell line as a model for human B cell activation. Spectrofluorometry was used to investigate mitogen-induced changes in [Ca++]i and transmembrane potential. Activation of human B cells with anti-mu antibodies resulted in a biphasic rise in [Ca++]i, the second phase being mediated by the influx of extracellular Ca++. Ca++ influx was inhibited by high [K+]e, suggesting that this influx was transmembrane potential sensitive. Membrane currents of Daudi cells were investigated using voltage clamp techniques. Before mitogenic stimulation, the cells were electrically quiet. Within several minutes of the addition of anti-mu antibodies to the bath solution, inward currents were observed at negative voltages. Whole-cell currents changed instantly with voltage steps and were transmembrane potential sensitive in that at potentials more positive than -40 mV no currents were detectable. A similar conductance was also activated by the introduction of IP3 into the intracellular solution, suggesting that IP3 generation after surface IgM crosslinking is involved in the activation of this conductance. Both anti-mu and IP3 induced currents were blocked by 1 mM La , which is known to block Ca++ channels. These results strongly support the presence of membrane Ca++ channels in human B cells that function in the early stages of activation. Changes in transmembrane potential appear to be important in regulating Ca++ influx. These mechanisms work in concert to regulate the level of [Ca++]i during the early phases of human B cell activation.

A lineage-specific Ca(2+)-activated K+ conductance in HL-60 cells.

Cells of the human promyelocytic cell line HL-60 can be controllably induced to terminally differentiate into either granulocytes or monocyte/macrophages. HL-60 promyelocytes and terminally differentiated macrophages express a K(+)-selective ion channel which is activated by intracellular free Ca2+ concentrations above 10(-7) M. Because of its voltage independence, this channel can be distinguished from the voltage- and Ca(2+)-activated family of outward-rectifying channels. The channel is selective for K+ against Na+ and is blocked by Ba2+, thus it may be similar to the Ca(2+)-activated K+ channel previously described in human macrophages. In its sensitivity to block by charybdotoxin, this channel also resembles a Ca(2+)-activated K+ channel of lymphocytes, which plays a role in activation-dependent hyperpolarization. In contrast to promyelocytes and macrophages, functional expression of the Ca(2+)-activated K+ channel is suppressed to nearly undetectable levels in granulocytes derived from HL-60 cells by retinoic acid-induced differentiation. These data suggest that signals which produce elevation of intracellular Ca2+ will hyperpolarize promyelocytes and differentiated macrophages by activating this conductance; however, signals which elevate free Ca2+ in granulocytes must act on other effectors, which may produce a different final influence on membrane potential.

Transmembrane ion conductance in human B lymphocyte activation.

Human B lymphocytes were examined to determine whether transmembrane ion conductance plays a role in cell activation. Mitogens (anti-human IgM F(ab')2 fragment (anti-mu) and PMA) were used to stimulate B lymphocytes. Mitogen-induced DNA synthesis was inhibited by tetraethylammonium-Cl (TEA), 4-aminopyridine (4AP), verapamil, and diltiazem in a dose-dependent manner. This inhibition was not due to reduction in cell viability as determined by trypan blue exclusion. Mitogen-induced increases in RNA synthesis were partially inhibited by TEA and 4AP and were more completely inhibited by verapamil and diltiazem. Mitogen-induced cell volume increases were not affected by TEA or 4AP but were completely inhibited by verapamil and diltiazem. B lymphocytes stimulated with anti-mu expressed G1 phase cell surface antigens in the presence of TEA or 4AP, but failed to do so in the presence of verapamil or diltiazem. Substitution of PMA for anti-mu as the mitogen did not alter the effects of TEA or 4AP. However, verapamil inhibited PMA-induced expression of G1 phase cell surface markers although diltiazem did not. The patch clamp technique was used to directly examine plasma membrane ionic currents in whole-cell, cell-attached, and inside-out patch configurations. Activation of B lymphocytes with either anti-mu or the Ca2+ ionophore, A23187, inhibited opening of one type of channel in cell-attached patches. In inside-out patches, this channel type conducted current when the bath [Ca2+] was low (6 X 10(-8) M) but failed to conduct current when the bath [Ca2+] was increased above 1 X 10(-6) M. The results of these experiments are consistent with the hypothesis that activation of B lymphocytes induces alterations in plasma membrane ion conductance. Single channel studies suggest that activation induced increases in [Ca2+]i may directly inhibit a specific set of plasma membrane ion channels as one mechanism by which transmembrane ion flux is altered.

Interleukin 2 production by a marmoset B cell line.

Several B cell lines constitutively secreting interleukin (IL) 2 were derived from the Epstein-Barr virus-positive marmoset B cell line, B95-8. A representative line, KRC-18, was cloned by limiting dilution and found to be 40% surface IgM+, 60% cytoplasmic IgM+, greater than 95% DR+, weakly Tac+ and devoid of T cell, monocyte and NK cell surface antigens. Supernatant from KRC-18 cells supported the long-term growth of an IL 2-dependent murine T cell line, HT-2, and contained 7-8 units/ml of IL 2 activity when compared to recombinant IL 2. The supernatant was fractionated by Sephadex G-75 gel filtration, and maximal proliferation of HT-2 cells was supported by the 20-22-kDa column fraction. The proliferative response of HT-2 cells to KRC-18 supernatant was inhibited by monoclonal antibodies to human IL 2 or the murine IL 2 receptor in a dose-dependent manner, suggesting that the KRC-18 IL 2 has epitopes that are similar to human IL 2, and that its activity is mediated through binding to the IL 2 receptor of the target cell line. When KRC-18 cells were analyzed for cytoplasmic IL 2, greater than 90% of the cells contained intracellular IL 2 in amounts equivalent to, or greater than, mitogen-activated T cells. These data indicate that certain B lineage cell lines are capable of IL 2 synthesis and secretion.

Localized eosinophilic fasciitis in a patient with rheumatoid arthritis.

A case of eosinophilic fasciitis localized to the left thenar eminence in a patient with active rheumatoid arthritis is described for the first time. The clinical and pathologic similarities to localized forms of scleroderma, and the features that help to distinguish these conditions are discussed.