Chromosome abnormalities in AIDS-associated lymphadenopathy

Cytogenetic studies were performed on direct and 24-hour culture preparations of eight lymph node biopsies from seven patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC)- associated lymphadenopathy in whom histological evidence of lymphoma was not detected. Three of these seven had chromosomal abnormalities, including chromosome instability in one and clonal chromosomal abnormalities in two; one of the latter was a t(8;14)(q24;q32). The remaining five showed normal karyotypes. Epstein-Barr virus (EBV) titers were elevated in all three patients that exhibited chromosome abnormalities, two of whom later developed malignant lymphoma. A control group of five patients with reactive lymphadenopathy not associated with AIDS failed to reveal chromosomal aberrations, but elevated EBV titers were present in two. These data are consistent with current views on the role of EBV and chromosome change in the development of lymphoma in immunodeficient states and suggest that karyotypically abnormal AIDS-related lymphadenopathy represents a prelymphomatous proliferation.     

CD34-deficient mice have reduced eosinophil accumulation after allergen exposure and show a novel crossreactive 90-kD protein

CD34 is expressed on the surface of hematopoietic stem/progenitor cells, stromal cells, and on the surface of high-endothelial venules (HEV). CD34 binds L-selectin, an adhesion molecule important for leukocyte rolling on venules and lymphocyte homing to peripheral lymph nodes (PLN). We generated CD34-deficient mutant animals through the use of homologous recombination. Wild-type and mutant animals showed no differences in lymphocyte binding to PLN HEV, in leukocyte rolling on venules or homing to PLN, in neutrophil extravasation into peritoneum in response to inflammatory stimulus, nor in delayed type hypersensitivity. Anti-L-selectin monoclonal antibody (MEL-14) also inhibited these immune responses similarly in both CD34-deficient and wild-type mice. However, eosinophil accumulation in the lung after inhalation of a model allergen, ovalbumin, is several-fold lower in mutant mice. We found no abnormalities in hematopoiesis in adult mice and interactions between mutant progenitor cells and a stromal cell line in vitro were normal. No differences existed in the recovery of progenitor cells after 5-fluorouracil treatment, nor in the mobilization of progenitor cells after granulocyte colony-stimulating factor treatment compared with wild-type animals. Surprisingly, although CD34 was not expressed in these mice, a portion of its 90-kD band crossreactive with MECA79 remained after Western blot. Thus, we have identified an additional molecule(s) that might be involved in leukocyte trafficking. These results indicate that CD34 plays an important role in eosinophil trafficking into the lung.     

Spurious detection of terminal deoxynucleotidyl transferase in phytohemagglutinin-stimulated lymphocytes

Expression of terminal transferase (TdT) is believed to be restricted to primitive lymphoid cells; recently, however, indirect immunofluorescent (IF) assays have been used to demonstrate the apparent presence of TdT in phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes and in various nonlymphoid malignancies. Using an IF assay, we found that a heteroantiserum to TdT reacted with cultured and PHA-stimulated human peripheral blood mononuclear cells, but we were unable to confirm the presence of TdT in these cells using immunoblotting and biochemical assays. We conclude that the IF results are spurious and most likely represent recognition by the heteroantiserum of inducible protein(s) other than TdT.     

Autoplex versus proplex: a controlled, double-blind study of effectiveness in acute hemarthroses in hemophiliacs with inhibitors to factor VIII

In view of uncontrolled observations and anecdotal reports suggesting that the activated PCC, Autoplex, was much more effective than standard (non-activated) PCC in controlling bleeding in hemophiliacs with inhibitors, a controlled double-blind study was designed to compare the effectiveness of Autoplex and Proplex. Acute hemarthrosis was chosen for study as this common but non-life-threatening lesion lends itself well to controlled study. A single dose of "unknown" product (Autoplex 75 FECU/kg; Autoplex 50 FECU/kg; or Proplex 75 FIX U/kg) was given, and effectiveness was judged at 6 hr. By all criteria of efficacy, there were no significant differences between the products. It is noteworthy that a single dose of PCC was judged effective in 50% of episodes, a figure that is consistent with other published clinical trials. In this model, no additional benefit was derived from using the activated PCC, Autoplex, in either dosage.     

Multimer size dependence of von Willebrand factor binding to crosslinked or noncrosslinked fibrin

von Willebrand factor (vWF) is synthesized in endothelial cells (EC) and may be either secreted constitutively or stored in Weibel-Palade bodies (WPB) for regulated release. Because fibrin stimulates rapid vWF release from EC, we examined the binding of EC synthesized vWF to fibrin. Culture medium containing constitutively secreted vWF was removed from metabolically labeled primary cultures of human umbilical vein EC, and vWF released from WPB was obtained after stimulation by A23187. vWF-deficient fibrinogen with or without factor XIII was added to releasate or media and clotted with thrombin to form crosslinked or noncrosslinked fibrin. vWF was immunopurified from releasate or media before and after clotting, and the amount and multimeric pattern of vWF bound was determined after sodium dodecyl sulfate agarose gel electrophoresis. High molecular weight multimers of vWF, whether secreted constitutively or released from WPB, bound preferentially to fibrin. Multimers of greater than 20 subunits represented 60% +/- 4% (SEM) of A23187 released vWF and 11% +/- 5% of media vWF, but binding to fibrin was similar, 96% +/- 1% and 94% +/- 2%, respectively. A progressively smaller proportion of vWF bound as multimer size decreased, and dimeric vWF binding was least, with 34% +/- 5% binding from A23187 releasate and 51% +/- 4% from media. The amount of vWF binding to crosslinked or noncrosslinked fibrin was similar, and preferential binding of high molecular weight multimers occurred with both. As measured by enzyme-linked immunosorbent assay, 45% +/- 2% of constitutively secreted vWF bound to crosslinked fibrin and 50% +/- 2% to noncrosslinked fibrin. The propolypeptide of vWF did not bind to fibrin. These findings indicate that binding of EC secreted vWF binding to fibrin depends on multimeric size but not on factor XIII crosslinking. This suggests that vWF released from EC in the presence of fibrin will bind locally, thereby facilitating platelet adhesion to the hemostatic plug or thrombus.     

Serum immunoreactive erythropoietin in children with cyanotic and acyanotic congenital heart disease

Serum immunoreactive erythropoietin (siEp) was measured in 27 cyanotic and 21 acyanotic children with congenital heart disease, age 4 months to 10 years. The geometric mean value was 9 mIU/mL for each group with 95% range from 3 to 26 mIU/mL and 4 to 22 mIU/mL for the cyanotic and acyanotic subjects, respectively. The levels are similar to those found in normal adults using the same assay system. Three cyanotic subjects showed increased siEp values. One was anemic relative to his hypoxemia, and the other two showed signs of increasing hypoxia. There was a significant negative correlation between siEp and arterial oxygen content. However, siEp did not correlate significantly with hemoglobin, hematocrit, PaO2, or SaO2. Despite normal siEp levels, the cyanotic children showed compensatory erythropoiesis with significantly elevated hemoglobin and hematocrit levels, which did correlate inversely with PaO2 and SaO2. Arterial oxygen content was also significantly higher in the cyanotic subjects (p less than 0.02). The cyanotic children seemed to display the same pattern as observed in man and animals exposed to prolonged hypobaric hypoxia, where after an initial rise in erythropoietin values the levels fall to normal, while increased erythropoiesis is sustained.     

Stimulation of interleukin-6 and prostaglandin E2 secretion from peritoneal macrophages by polymers of albumin

Interleukin-6 (IL-6) is a multifunctional cytokine that is elevated in vivo during acute infection, chronic inflammation, and some hematopoietic malignancies. To understand how IL-6 becomes elevated in vivo, it is important to identify factors that can stimulate its secretion from effector cells. We found that commercial preparations of bovine serum albumin (BSA) stimulated murine macrophages to secrete high levels of IL-6. In fact, BSA was at least as potent as bacterial lipopolysaccharide (LPS) in stimulating IL-6 production. Stimulation was clearly visible at concentrations as low as 20 micrograms/mL and reached saturation at 0.5 to 1 mg/mL albumin, at which concentration 1.1 x 10(6) oil-elicited macrophages produced 6,000 +/- 700 B9 units of IL-6 in an overnight incubation. Prostaglandin E2 production was induced by the same concentrations of BSA. Both resident and oil- elicited peritoneal cells were responsive to the albumin. The stimulatory activity did not derive from contamination of the protein with Escherichia coli LPS; when compared directly with LPS, the response to BSA was more rapid, had a higher amplitude, and was not inhibitable by polymyxin B. In addition, macrophages isolated from C3H/HeJ mice, which have an inherited defect in their ability to respond to LPS, secreted IL-6 in response to BSA but not to LPS. The stimulatory activity was stable to heat, mild acid, and reduction/alkylation and copurified with albumin on Cibachron Blue agarose (Sigma, St Louis, MO) and anti-albumin immunoaffinity chromatography. Comparison of different sources and preparations of albumin showed differences in the levels of IL-6-inducing activity; three different lots of commercial fatty acid-free BSA and one lot of polymer-enhanced BSA stimulated IL-6 secretion by more than 100-fold over basal levels whereas other preparations showed more limited activity. A sample of BSA that was active in vitro caused a marked elevation of IL-6 when injected into BALB/c mice, thus demonstrating inflammatory activity in vivo. When the albumin preparations were fractionated by ion exchange and gel filtration chromatography and then analyzed by sodium dodecyl sulfate-gel electrophoresis and Western blot immunoassay, it was found that the IL-6-inducing activity resided in high molecular weight polymers of albumin. The ability of albumin polymers to stimulate IL-6 production represents a novel mechanism for modulation of this cytokine.     

Phase I trial of recombinant human macrophage colony-stimulating factor in patients with invasive fungal infections

A phase I dose escalation trial of recombinant human macrophage colony- stimulating factor (rhM-CSF) in combination with conventional antifungal therapy was conducted in 24 marrow transplant recipients with invasive fungal infection. Daily doses ranged from 100 to 2,000 micrograms/m2/d. Toxicity, such as constitutional symptoms, directly ascribed to rhM-CSF was not observed; however, transient, dose-related thrombocytopenia was observed. Patients who received 2,000 micrograms/m2/d of rhM-CSF had a mean reduction in platelet count of 61,000/mm3 during the rhM-CSF infusion period, which was significant when compared with patients who received lower doses of rhM-CSF (P = .008). Fourteen of the 16 patients who received rhM-CSF after undergoing allogeneic bone marrow transplantation had no change in the severity of graft-versus-host disease (GVHD) while receiving rhM-CSF. One had an increase in the severity of GVHD and one had a decrease. There were no effects on neutrophil, monocyte, or lymphocyte counts. Six patients had resolution of their infections, 12 were not evaluable for response, and six did not respond. Ten patients survived 100 days after initiation of rhM-CSF and 14 died. Further trials with rhM-CSF to assess antifungal activity are indicated.