Peripheral blood-derived, γ9δ2 t cell-enriched cell lines from glioblastoma multiforme patients exert anti-tumoral effects in vitro.

The goal of this work was to assess the potential of T cells expressing Vγ9Vδ2+ T cell receptors (TCR, γ9δ2T cells) present in peripheral blood (PB) m ononuclear cells (MC, PBMC) of glioblastoma multiforme (GBM) patients to act as anti-tumoral agents. We found that γ9δ2T cell levels were decreased in patients' PB relative to a cohort of healthy donors (HD) (respectively 0.52±0.55%, n=16, vs 1.12±0.6%, n=14, p=0.008) but did not significantly correlate with postoperative survival (R=0.6, p=0.063). Importantly, however, the γ9δ2T cells could be expanded in vitro to consist 51±23% of the cultured lymphocytes (98% CD3+). This was achieved after 14 days of culture in medium containing the amino-bisphosphonate (ABP) Zoledronate (Zol) and interleukin (IL)-2, resulting in γ9δ2T cell-enriched lines (gdTCEL) similar to those of HD derived gdTCEL (54±19%). Moreover, gdTCEL from patients and HD mediated cytotoxicity to GBM-derived cell lines (GBMDCL), which was abrogated by immune-magnetic removal of the γ9δ2T cells. Furthermore, low level interferon (IFN) γ secretion was induced by gdTCEL briefly co-cultured with GBMDCL or autologous - tumor-derived cells, which was greatly amplified in the presence of Zol. Importantly, IFNγ secretion was inhibited by mevastatin but enhanced by cross-linking of butyrophilin 3A1 (CD277) on a CD277+ GBMDCL (U251MG) or by pretreatment of GBMDCL with temozolomide (TMZ). Taken together, these data suggest that γ9δ2T cells in PB of GBM patients can give rise to gdTCEL that mediate anti-tumoral activities.

Donors' health state the year after peripheral haematopoietic progenitor cell collection: A prospective follow-up study in related and unrelated donors compared to first-time platelet donors.

Granulocyte colony-stimulating factor (G-CSF) mobilized peripheral haematopoietic progenitor cells collected by apheresis (HPC-A) are the most common source used for allogeneic hematopoietic stem cell transplantation (HSCT). Retrospective short and long-term donor follow-up studies show very low risks of serious complications and do not report compelling evidence of increased cancer occurrence. Some studies reported a prolonged period of leucopenia without an obvious association with infectious complications. However, beyond the first few weeks after the procedure a relationship between events is elusive. We therefore evaluated medical service utilization by prospectively recruited HPC-A donors and first-time platelet apheresis donors for comparison for 1 year after donation. Data were prospectively collected using questionnaires and by medical record review. A total of 215 HPC-A donors (111 unrelated donors and 104 related donors) and 96 first-time platelet donors consented to participation in the study. Follow-up was available for 202 (96%): questionnaires were returned by 74% and records from nonstudy contacts were available for 94% of donors. During the 1-year follow-up, 94 of the donors who returned questionnaires sought medical attention for diagnostic evaluation and/or treatment: 41% of HPC-A donors and 40% of platelet donors. Medical service utilization the first year after HPC-A donation is similar to that after first-time platelet donation. The occurrence of serious medical conditions in both related and unrelated HPC-A donors underscores the importance of participation in long-term follow-up in large cohorts. The findings in this relatively small cohort contribute to evidence on the safety of G-CSF mobilization and HPC-A. J. Clin. Apheresis 31:523-528, 2016. © 2015 Wiley Periodicals, Inc.

The ethnicity-specific association of biomarkers with the angiographic severity of coronary artery disease.

BACKGROUND: Risk factor burden and clinical characteristics of patients with coronary artery disease (CAD) differ among ethnic groups. We related biomarkers to CAD severity in Caucasians, Chinese, Indians and Malays. METHODS: In the Dutch-Singaporean UNICORN coronary angiography cohort (n = 2033) we compared levels of five cardiovascular biomarkers: N-terminal pro-brain natriuretic peptide (NTproBNP), high-sensitivity C-reactive protein (hsCRP), cystatin C (CysC), myeloperoxidase (MPO) and high-sensitivity troponin I (hsTnI). We assessed ethnicity-specific associations of biomarkers with CAD severity, quantified by the SYNTAX score. RESULTS: Adjusted for baseline differences, NTproBNP levels were significantly higher in Malays than in Chinese and Caucasians (72.1 vs. 34.4 and 41.1 pmol/l, p < 0.001 and p = 0.005, respectively). MPO levels were higher in Caucasians than in Indians (32.8 vs. 27.2 ng/ml, p = 0.026), hsTnI levels were higher in Malays than in Caucasians and Indians (33.3 vs. 16.4 and 17.8 ng/l, p < 0.001 and p = 0.029) and hsTnI levels were higher in Chinese than in Caucasians (23.3 vs. 16.4, p = 0.031). We found modifying effects of ethnicity on the association of biomarkers with SYNTAX score. NTproBNP associated more strongly with the SYNTAX score in Malays than Caucasians (ß 0.132 vs. ß 0.020 per 100 pmol/l increase in NTproBNP, p = 0.032). For MPO levels the association was stronger in Malays than Caucasians (ß 1.146 vs. ß 0.016 per 10 ng/ml increase, p = 0.017). Differing biomarker cut-off levels were found for the ethnic groups. CONCLUSION: When corrected for possible confounders we observe ethnicity-specific differences in biomarker levels. Moreover, biomarkers associated differently with CAD severity, suggesting that ethnicity-specific cut-off values should be considered.

Perturbation of the T4 molecule transmits a negative signal to T cells.

We investigated the functional role of the T4 molecule in the activation of T cells by OKT3. T4+ cells were induced to proliferate by OKT3 and erythrocyte rosette-negative accessory cells in the presence or absence of OKT4C, OKT4, and OKT1. OKT4C (IgG1), and not OKT4 (IgG2) or OKT1 (IgG1) inhibited proliferation when OKT4C was added during the first 24 h of cell culture. The inhibition of OKT3 activation by OKT4C did not require Ia+ accessory cells, since T4+ cells could be activated by OKT3 in the presence of Ia- U937 cells, and this activation was markedly inhibited by OKT4C. Furthermore, T4+ cells could be induced to proliferate by OKT3 covalently linked to Sepharose beads, in the absence of any accessory cells. Under these conditions, OKT4C, but not OKT4 or OKT1 significantly inhibited proliferation. These data demonstrate that at least one mechanism by which anti-T4 antibodies inhibit T cell activation is independent of any putative role of T4 molecules in the recognition of Ia on target cells. The data are compatible with the idea that perturbation of the T4 molecules can transmit a negative signal to T4+ cells.

Tumor necrosis factor/cachectin interacts with endothelial cell receptors to induce release of interleukin 1.

Tumor necrosis factor/cachectin (TNF) has been implicated as a mediator of the host response in sepsis and neoplasia. Recent work has shown that TNF can modulate endothelial cell hemostatic properties, suggesting that endothelium is a target tissue for TNF. This led us to examine whether endothelial cells have specific binding sites for TNF and augment the biological response to TNF by elaborating the inflammatory mediator, IL-1. Incubation of 125I-recombinant human TNF with confluent, cultured human umbilical vein endothelial cells resulted in time-dependent, reversible, and saturable binding. Binding was half-maximal at a TNF concentration of 105 +/- 40 pM, and at saturation 1,500 molecules were bound per cell. Heat-treated TNF, which is biologically inactive, did not bind to endothelium. In addition to surface binding, TNF induced the elaboration of IL-1 activity by endothelial cells in a time-dependent manner. Generation of IL-1 activity required protein synthesis and was half-maximal at a TNF concentration of 50 +/- 20 pM. IL-1 activity from TNF-treated endothelium could be adsorbed by an immobilized antibody to IL-1. Heat-treated TNF was ineffective in eliciting endothelial cell IL-1. These data indicate that TNF can bind specifically to endothelium and initiate a cascade of inflammatory and coagulant events on the vessel surface potentially central to the host response to neoplasia and sepsis.

Structure of the gamma/delta T cell receptor of a human thymocyte clone.

The CD3+, IL-2-dependent normal human thymocyte clone, CII, expresses on its surface a CD3-associated gamma/delta TCR. We have further elucidated the structure of this receptor from the nucleotide sequence of cDNA and genomic clones from CII that encode functional TCR-gamma and -delta chains. We find that the CII line expresses a C gamma 2 constant region that is a polymorphic form lacking a copy of an internal exon; the sequence of this constant region accounts for the size of the gamma chain and noncovalent linkage of gamma and delta chains in the CII TCR. The V gamma region used for the CII TCR is identical to the several previously characterized expressed human V gamma segments. Possible implications of this finding are discussed.

Characterization of a third form of the human T cell receptor gamma/delta.

A subpopulation of the CD3+ peripheral T lymphocytes express the TCR-gamma/delta complex. Three distinct TCR-gamma forms that differ in size and in the ability to form a disulfide bridge with the TCR-delta subunit have been described. In this study we analyze the structural difference between the non-disulfide-linked 55-kD and 40-kD TCR-gamma chains. The 40-kD TCR-gamma form contains a smaller polypeptide backbone and carries less carbohydrate compared with the 55-kD TCR-gamma form. A cDNA clone corresponding to the 40-kD TCR-gamma subunit lacks one copy of the second exon of the constant region that is present in the other TCR-gamma subunit. This exon copy encodes part of the connector region that is located between the constant domain and the membrane spanning region. We show that the number of potential N-linked glycan attachment sites are the same for the two TCR-gamma forms. Since these attachment sites are located in the connector region we conclude that the connector region influences the amount of N-linked carbohydrates added to the core TCR-gamma polypeptide, probably by affecting the conformation of the protein. In contrast to the TCR-beta constant region usage, the TCR-gamma constant regions are unequally expressed. Virtually exclusive usage of disulfide-linked complexes were found in some individuals, while both the disulfide-linked and the 40-kD, non-disulfide-linked TCR-gamma forms were detected in other subjects. The ability to distinguish these TCR-gamma/delta forms now makes it possible to study the mechanisms that govern their selection and to determine if they correspond to functionally distinct isotypes.

Self-regulation of procoagulant events on the endothelial cell surface.

Interleukin 1 (IL-1) is a potent mediator of inflammatory and immunologic phenomena. In addition, IL-1 may be intimately involved in the regulation of hemostasis, since interaction of IL-1 with endothelial cells has been reported to induce tissue factor activity. We demonstrate that perturbation of the endothelial cell induces augmented IL-1 release. Human umbilical vein endothelial cells perturbed by treatment with lipopolysaccharide produced enhanced amounts of IL-1 activity. IL-1 activity from lipopolysaccharide-treated endothelial cell supernatants could be absorbed by an antibody to IL-1 coupled to Sepharose. Elaboration of IL-1 activity was dependent on the dose of lipopolysaccharide and occurred in a time-dependent manner. Addition of cycloheximide blocked generation of IL-1 activity. A physiological vessel wall perturbant, the coagulation enzyme thrombin, induced comparable amounts of IL-1 activity in endothelial cell cultures. This effect was specific for the enzyme, since active site-blocked thrombin and prothrombin had no effect on IL-1. In addition, IL-1-containing supernatants from thrombin-stimulated endothelial cells induced tissue factor procoagulant activity in fresh endothelial cell cultures. Thus, in contrast to the multiple, known inhibitory mechanisms that block thrombin procoagulant activity, these data suggest a circle of interaction in which thrombin induces endothelial cell elaboration of IL-1, a mediator of endothelial cell procoagulant activity. Endothelial cell production of IL-1 in response to perturbation allows these cells to play an integral role in the regulation of the inflammatory and coagulation systems.

Early preservation of effector functions followed by eventual T cell memory depletion: a model for the delayed onset of the effect of thiopurines.

OBJECTIVE: The onset of the effect of thiopurines is delayed for several months. The aim of this study was to investigate immune mechanisms for this delay. METHODS: The effects of thiopurines on human peripheral blood T cells and on lamina propria lymphocytes were investigated for apoptosis induction by Annexin V/propidium iodide (PI) and for cytokine secretion by intracellular staining and ELISA assays. To investigate the mechanism of the effect of thiopurines in vivo, Balb/C mice were co-immunised with HEL/OVA (hen egg lysozyme/ovalbumin) antigens, and then repeatedly challenged by HEL only, while being treated by mercaptopurine or vehicle alone for either 4 or 20 weeks. The memory response of CD4+ splenocytes towards HEL/OVA was then determined by CFSE (carboxyfluorescein succinimidyl ester) dilution. RESULTS: Thiopurines arrested the proliferation of stimulated T cells but did not enhance the apoptosis of either resting T cells or activated T cells until day 5 poststimulation. Despite the proliferation arrest, stimulated T cells successfully differentiated into effector cells, as evidenced by their capacity for proinflammatory cytokine secretion, potent adhesion and cytotoxicity. Prolonged mercaptopurine treatment of mice for 20 weeks selectively reduced the CD4+ memory response to a repeatedly encountered HEL antigen, but did not affect the T cell memory pool to the previously presented OVA antigen. A shorter, 4 weeks, treatment with mercaptopurine did not inhibit the memory response to either antigen. CONCLUSIONS: T cells arrested from cycling by thiopurines can still differentiate into potent effector cells capable of propagating the inflammatory process. Thiopurine treatment results in depletion of antigen-specific memory T cells, but this effect is dependent upon repeated encounters with the antigen over a prolonged time course.

Collagen and collagenase gene expression in three-dimensional collagen lattices are differentially regulated by alpha 1 beta 1 and alpha 2 beta 1 integrins.

The reorganization of extracellular matrix (ECM) is an important function in many biological and pathophysiological processes. Culture of fibroblasts in a three-dimensional collagenous environment represents a suitable system to study the underlying mechanisms resulting from cell-ECM interaction, which leads to reprogramming of fibroblast biosynthetic capacity. The aim of this study was to identify receptors that transduce ECM signals into cellular events, resulting in reprogramming of connective tissue metabolism. Our data demonstrate that in human skin fibroblasts alpha 1 beta 1 and alpha 2 beta 1 integrins are the major receptors responsible for regulating ECM remodeling: alpha 1 beta 1 mediates the signals inducing downregulation of collagen gene expression, whereas the alpha 2 beta 1 integrin mediates induction of collagenase (MMP-1). Applying mAb directed against different integrin subunits resulted in triggering the heterodimeric receptors and enhancing the normal biochemical response to receptor ligation. Different signal transduction inhibitors were tested for their influence on gel contraction, expression of alpha 1(I) collagen and MMP-1 in fibroblasts within collagen gels. Ortho-vanadate and herbimycin A displayed no significant effect on any of these three processes. In contrast, genistein reduced lattice contraction, and completely inhibited induction of MMP-1, whereas type I collagen down-regulation was unaltered. Calphostin C inhibited only lattice contraction. Taken together, these data indicate a role of tyrosine-specific protein kinases in mediating gel contraction and induction of MMP-1, as well as an involvement of protein kinase C in the contraction process. The data presented here indicate that different signaling pathways exist leading to the three events discussed here, and that these pathways do not per se depend upon each other.

Very late antigen-1 in psoriasis: an immunohistochemical study.

BACKGROUND: Currently, psoriasis is thought to be an inflammatory response to an antigenic stimulation, in which angiogenesis plays a fundamental role. Very late antigen-1 (VLA-1) is a beta(1) integrin collagen receptor that is up-regulated in many angiogenic processes. Data on its role in psoriasis are sparse. OBJECTIVE: In a prospective study, we evaluated the staining of VLA-1 in lesional skin from patients with psoriasis and atopic dermatitis. MATERIAL AND METHODS: Frozen sections from skin biopsies of patients with chronic plaque-type psoriasis (n = 18) and chronic atopic dermatitis (n = 7) were stained with a monoclonal antibody to VLA-1. The number of blood vessels stained with VLA-1 and the staining intensity were evaluated. These were correlated with the histologic features. RESULTS: The absolute number of blood vessels was found to be similar in the atopic and psoriatic samples. However, the number of vessels stained with anti-VLA-1, as well as the staining intensity, was shown to be significantly higher in the psoriasis group (P < 0.05). Differences between psoriatic lesions showing typical histological features of psoriasis and those showing features that overlap with dermatitis were found as well. CONCLUSIONS: Expression of VLA-1 was found significantly higher in lesional dermal blood vessels of psoriatic patients compared with atopic patients. These findings suggest a possible role for VLA-1 in the pathological angiogenesis of psoriasis. It may be an additional tool for establishing the diagnosis of psoriasis and provide a basis for new strategies in the treatment of psoriasis.

Elevated levels of FVIII:C within families are associated with an increased risk for venous and arterial thrombosis.

Elevated levels of coagulation factor VIII:C (FVIII:C) are associated with an increased risk for venous and arterial thromboembolism. Whether relatives of patients with elevated levels of FVIII:C are also at increased risk for thrombotic disease is unknown. The objective was to determine the annual incidences of both venous and arterial thrombotic events in first-degree relatives of patients with elevated levels of FVIII:C and venous thromboembolism (VTE) or premature atherosclerosis. A retrospective study with 584 first-degree relatives of 177 patients with elevated levels of FVIII:C was performed. The level of FVIII:C was determined and relatives with elevated and normal levels of FVIII:C were compared. Of the participants, 40% had elevated levels of FVIII:C. The annual incidence of a first episode of VTE was 0.34% and 0.13% in relatives with elevated levels of FVIII:C and those with normal levels, respectively [OR 3.7 (95% CI 1.9-7.5)]. The absolute annual incidence in the youngest age group with elevated levels of FVIII:C was 0.16% (0.05-0.37) and gradually increased to 0.99% (0.40-2.04) in those older than 60 years of age, although the odds ratios were not statistically significant. The annual incidences of a first arterial thrombotic event were 0.29% and 0.14% in relatives with and without elevated levels of FVIII:C, respectively [OR 3.1 (1.4-6.6)]. In particular the risks for a first myocardial infarction [OR 4.3 (1.0-18.1); P =0.046] and a first peripheral arterial thrombosis [OR 8.6 (1.6-47.6)] were increased. Within families of patients with elevated levels of FVIII:C and VTE or premature atherosclerosis, 40% of their first-degree relatives has elevated levels of FVIII:C as well, and they are at increased risk for both VTE and arterial thrombosis as compared with their relatives with normal levels.

Analysis of cell-free human alpha1 integrin with a monoclonal antibody to the I-domain: detection in ocular fluid and function as an adhesion substrate.

The alpha1 beta1 integrin, an inserted (1) domain containing collagen receptor, is expressed in the cell surface membrane of normal and malignant cells, and may play a role in their migration through tissues or in metastatic spread. Here we report that a functional anti-human alpha1beta1 integrin monoclonal antibody (mAb) (1B3.1) directly and specifically binds plastic bound recombinant human alpha1 I-domain protein containing the collagen binding site. Detection was diminished by acidification of the I-domain protein but was enhanced by increasing concentrations of Mg2+ cation. Furthermore, we detected binding of the mAb to proteins from the ocular fluids of 6 patients, with the highest concentration, corresponding to 22.1 ng/ml of I-domain, found in a sample from the eye of a patient with metastatic lung adenocarcinoma. Interestingly, we found that both SKNSH neuroblastoma cells and virally transformed human T cells adhered specifically to plastic wells coated with either immobilized collagen IV or alpha1 I-domain. MAb I B3.1 inhibited adhesion to collagen IV but not to immobilized I-domain. These results suggest a novel function for cell free alpha1 I-domain as a substrate for cellular adhesion, which may have relevance in tumor spread in vivo.

Aspergillosis in systemic lupus erythematosus.

Infection is the major cause of morbidity and mortality in systemic lupus erythematosus (SLE). Although various fungi account for a substantial number of these lethal infections, aspergillosis, an important opportunistic infection in immunosuppressed patients, is described rarely. Only 23 cases have been reported in the English-language medical literature. Risk factors for acquiring aspergillosis in these patients were high grade disease activity, granulocytopenia, use of steroids and other immunosuppressive treatment and presence of bacterial infection. The diagnosis in most patients was delayed and they died. Here, we describe three SLE patients with invasive aspergillosis. Features of our patients' diseases were similar to those reported previously. Aspergillosis appeared while they had active SLE treated with high dose corticosteroids. In 2 patients the fungal infection was systemic and diagnosed post mortem. Both were leukopenic and had concurrent bacterial infection and one received amphotericin B prior to death. In the third, the infection was localized to a transplanted kidney and was cured by nephrectomy. Aspergillosis should be suspected in patients with active SLE, who are immunocompromised and sustain concomitant bacterial infections. The currently poor prognosis may be improved with more aggressive diagnostic investigation and treatment.

High incidence of malignancies in patients with dermatomyositis and polymyositis: an 11-year analysis.

OBJECTIVES: Dermatomyositis and polymyositis (DM/PM) are associated with neoplasms. The aim of the present study is to compare our experience in Israel with other published data. METHODS: Thirty-five adult patients with DM/PM, admitted to Sheba Medical Center during the 11-year interval between 1984 and 1994, were studied for the prevalence and features of malignant diseases. Patients with DM/PM alone and with DM/PM and malignancy were identified by using the hospital computer system. The manifestations of DM/PM and features of the malignant diseases were abstracted from the patients' charts. The presence or absence of malignancy and the type of cancer were verified in the National Cancer Registry. RESULTS: There were 15 men and 20 women. The mean age at the onset of the disease was 53 +/- 18 years. A total of 15 had PM and 20 DM. Malignancies occurred in four patients with PM (27%) and in nine with DM (45%) a frequency 12.6 times higher than in the general population. In six patients, the malignancy and the DM/PM were diagnosed simultaneously; in four before and in three after the appearance of the DM/PM. Hematologic, gastrointestinal, breast, ovarian, and lung tumors, malignant melanoma, and metastatic carcinoma of unknown primary were found among our patients. Eight DM/PM patients with malignancy died during the study period of infection, pulmonary embolism, and tumor spread. CONCLUSIONS: Our study found that DM/PM is associated with high rates of malignancy and mortality.

A novel 26 kilodalton antigen expressed on the surface membrane of activated T cells.

We have identified and characterized the tissue distribution of the antigen recognized by a novel monoclonal antibody (mAb) 1B10, raised against an activated gammadelta T cell clone. Immunohistochemistry of tissue sections, and analysis of single cell suspensions by flow cytometry revealed that mAb 1B10 weakly reacted with <6% of normal human peripheral blood mononuclear cells (PBMC). After 5-6 days of in vitro culture of PBMC activated with phytohemagglutinin (PHA), 55% of the CD4+ and 25% of the CD8+ T cells became 1B10+. 1B10 expression was maintained on long term cultured interleukin 2 (IL-2)-dependent T cell receptor (TCR) alphabeta+ and gammadelta+ clones, and importantly, in contrast to resting T cells, the majority of in vivo activated synovial T lymphocytes from a patient with rheumatoid arthritis were 1B10+. In addition, myelo-monocytic U927 cells, tissue macrophages and some epithelia and fibroblasts were found to react with mAb 1B10. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of molecules immuno-precipitated by mAb 1B10 from radio-iodinated cell surface membrane lysates of T lymphocyte and U937 cells revealed 26 and 29 kiloDalton (kDa) glycoproteins respectively. In conclusion, mAb 1B10 recognizes a novel <> appearing 26 kDa T cell activation antigen that may be useful for further studies of activated T cells in health and disease.

Parenteral administration of an activating monoclonal antibody to the alpha1beta1 integrin in dogs.

In mice, monoclonal antibody (mAb) to the alpha1 integrin abrogate gastro-intestinal damage during graft-versus-host-disease (GVHD), suggesting anti alpha1 mAb as candidates for treatment in humans as well. Our current data show that one such reagent, mAb 1B3.1, when immobilized to plastic wells via rabbit- anti murine (ram) immunoglobulin (Ig) induces a protein kinase-dependent spreading of activated human T cells. Furthermore, it significantly increases the proliferative response, and expression of interleukin-2 (IL-2) receptors (R) and CD69, of resting T cells, expressing minimal integrin on the cell surface, to sub-optimal stimulation by anti-CD3 mAb. We found, in addition, that mAb 1B3.1 a) immuno-precipitates alpha1beta1 integrins from cell-surface iodinated canine epithelial cells b) is highly reactive with canine T cells after their activation and c) inhibits adhesion of canine T cells to collagen IV. Despite the potential ability of the mAb to co-activate T cells in vitro, two dogs that received 4 injections of 0.5-0.3 mg/Kg of mAb 1B3.1 remained healthy, developing only marginal transient lymphopenia. Injection of 0.75mg/Kg in a third dog induced a more marked lymphopenia, and an additional dose of 1.0 mg/Kg 2 weeks later was followed by gastrointestinal hemorrhage. importantly, the lymphopenia was associated with a greater and more persistent decrease of CD8+ than of CD4+ T cells, leading to an increase in the CD4/CD8 ratio 24 hours after the injection. Thus, despite it's co-activating effects in vitro, administration of this mAb in vivo is feasible when appropriately dosed, and may have immuno-modulatory effects.

Positive antineutrophil cytoplasmic antibodies-associated vasculitis presenting with hemoptysis and a mediastinal mass.

A patient with end-stage renal failure, due to IgA nephropathy, was found to have a mediastinal mass. Biopsy specimen of the mass showed a necrotizing vasculitis. Antineutrophil antibodies to myeloperoxidase were strongly positive. To our knowledge, no case of a mediastinal mass due vasculitis has been reported in the literature, and our observation should lead to broadening of the spectrum of clinical manifestations of vasculitis.

A tale of two homocysteines--and two hemodialysis units.

Pharmacologic doses of folic acid are commonly used to reduce the hyperhomocysteinemia of end-stage renal disease (ESRD). Vitamin B12 acts at the same metabolic locus as folic acid, but information is lacking about the specific effects of high doses of this vitamin on homocysteine levels in renal failure. We therefore compared the plasma homocysteine concentrations of maintenance hemodialysis patients in two McGill University-affiliated urban tertiary-care medical centers that differed in the use of vitamin B12 and folic acid therapy. Patients in the first hemodialysis unit are routinely prescribed high-dose folic acid (HI-F, 6 mg/d), whereas those in the second unit receive high-dose vitamin B12 in the form of a monthly 1-mg intravenous injection, along with conventional oral folic acid (HI-B12, 1 mg/d). Predialysis homocysteine was 23.4 +/- 6.8 micromol/L (mean +/- SD) in the HI-F unit and 18.2 +/- 6.1 micromol/L in the HI-B12 unit (P < .002). Postdialysis homocysteine was 14.5 +/- 4.1 in the HI-F unit and 10.6 +/- 3.4 micromol/L in the HI-B12 unit (P = .0001). Multiple regression analysis indicated that high-dose parenteral vitamin B12 was associated with a lower homocysteine concentration even after controlling for the potential confounders of sex, serum urea, serum creatinine, urea reduction ratio, and plasma cysteine. Because this was a cross-sectional observational study, we cannot exclude the possibility that unidentified factors, rather than the different vitamin therapies, account for the different homocysteine levels in the two units. Careful prospective studies of the homocysteine-lowering effect of high-dose parenteral vitamin B12 in ESRD should be undertaken.