Massive apoptosis of bone marrow cells in aplastic anaemia

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Antigenic targets and pathogenicity of anti-aortic endothelial cell antibodies in takayasu arteritis

Anti-endothelial cell antibodies are considered to have an important role in the pathogenesis of Takayasu arteritis (TA). Previously, these antibodies were detected using human umbilical vein endothelial cells, which do not completely represent the antigenicity/functions of aortic endothelial cells, the specific targets in TA. To delineate the precise role of antigenic targets, we investigated such targets as well as the pathogenic mechanism of antibodies directed against aortic endothelial cells (AAECAs) in TA

Nocardiosis in patients of chronic idiopathic thrombocytopenic purpura on steroids

We present two cases of chronic idiopathic thrombocytopenic purpura (ITP) on prolonged steroid therapy who developed subcutaneous and brain abscesses due to Nocardia asteroides. The special diagnostic and therapeutic challenges encountered in the patients because of severe thrombocytopenia are being highlighted

Immune mechanisms in vasculopathies

Soniya Nityanand AB STRACT Most of the inflammatory vasculopathies, termed as vasculitides are considered to be mediated at least in part by immunopathogenic mechanisms. With the recent demonstration of immune cells in atherosclerotic plaques, immune mechanisms are considered to play an important role in atherosclerotic vasculopathies too. The main components involved in the immune-mediated vascular injury are immune complexes, antibodies to vascular wall antigens and T cells. These components may be involved singly or in consort to each other in a particular disease state. The aims of the present study were to investigate the role of (a) T cells in 2 groups of vasculitides - Wegener's granulomatosis (WG) and Takayasu's arteritis (TA); (b) anti-cardiolipin (ACLA) and anti-endothelial cell antibodies (AECA) in TA; (c) ACLA, AECA and circulating immune complexes (CICs) in myocardial infarction and in early onset atherosclerosis of peripheral vasculature; (d) CICs in vasculitis associated with hepatitis B and C infections and the role of anti-viral therapy in such cases. In both WG and TA, there were expanded populations of different AV/BV TCR bearing peripheral blood T cells. In WG a number of these had dramatic magnitudes. The expanded populations were HLA DR+, CD25+, CD28+ and either CD45RA+ or RO+. In WG, a more detailed study of the expanded populations showed them to persist in an activated state and in same magnitude for the total observation time of 28-38 months, irrespective of the disease going into clinical remission. Functionally the expanded populations were activated. These populations expressed and secreted the studied cytokines IL-2, IL-4, IFNy and GM-CSF. The activated status and secretion of cytokines by the expanded populations shows their involvement in the pathogenesis of WG. Most of the expanded populations were clonal and a further study would help in the elucidation of the inciting antigen. A higher prevalence of ACLA and AECA was observed in TA patients with a correlation with disease activity. A higher prevalence of ACLA and AECA was also observed in MI and peripheral atherosclerosis patients. A significant observation was that the levels of IgG and IgA ACLA at 50 years of age were predictive of the susequent occurrence of MI between 50-70 years of age and mortality related to it, independent of other conventional risk factors. Fifty % of peripheral atherosclerosis patients had CICs with a proppensity for those with C4 null alleles to have CICs. All the 7 patients with vasculitis associated with hepatitis B and C infections had high levels of CICs/cryoglobulins containing hepatitis Ags/Abs/genome. With anti-viral therapy all the 7 patients showed a rapid clinical improvement in the vasculitis and a concomitant sharp decline in CICs/cryoglobulins. 6 patients went into long lasting remissions with clearence of hepatitis Ags/genome from serum and CICs

Expression of interferon-γ and tumor necrosis factor-α in bone marrow T cells and their levels in bone marrow plasma in patients with aplastic anemia

Immune-mediated stem cell damage has been postulated to be responsible for disease initiation and progression in aplastic anemia (AA). It is hypothesized that T lymphocytes play a major role in destroying the bone marrow (BM) stem cells of AA patients by infiltrating the BM and secreting excessive levels of anti-hematopoietic cytokines, interferon-gamma (IFN- γ), and tumor necrosis factor-alpha (TNF-α). We undertook this study to assess the pathogenic significance of anti-hematopoietic cytokines such as IFN- γ and TNF-α in BM T cells and plasma of AA patients. Significantly elevated levels of IFN- γ and TNF-α were found in the BM plasma of AA patients compared to controls (p=0.05 and 0.006, respectively). Intracellular IFN- γ and not TNF-α in BM CD3+ T cells of AA patients was significantly higher compared to controls (p=0.04 and p=0.2, respectively). A follow-up analysis of expression of these cytokines in BM T cells and their levels in BM plasma in five AA patients before and 180 days (6 months) after antithymocyte globulin (ATG) and cyclosporin A (CsA) therapy showed a decline 180 days after therapy compared to pre-therapy. We thus conclude that increased production of both IFN-γ and TNF-α in the BM may contribute to disease pathogenesis in AA and ATG therapy may induce hematological remission by suppressing the elevated levels of IFN-γ and TNF- α in AA BM

Reactivity of γ/δ T cells to human 60-kd heat-shock protein and their cytotoxicity to aortic endothelial cells in Takayasu arteritis

Objective: Increased numbers of circulating γ/δ T cells with a restricted T cell receptor repertoire, as well as colocalization of the expression of heat-shock protein Hsp60/65 and γ/δ T cells in the arterial lesions of patients with Takayasu arteritis (TA), indicate that γ/δ T cells may react to Hsp60 and cause damage to the arterial endothelium. In this study we investigated the proliferative responses of γ/δ T cells to human Hsp60 and their cytotoxicity to human aortic endothelial cells (ECs) in patients with TA.Methods: Blood samples were obtained from 12 patients with TA, 8 patients with systemic lupus erythematosus (SLE) (as disease controls), and 10 healthy control subjects. Proliferative responses of circulating γ/δ T cells to human Hsp60 were detected by flow cytometry-based bromodeoxyuridine incorporation assay. Cytotoxicity of the γ/δ T cells to human aortic ECs was analyzed by colorimetric lactate dehydrogenase release assay.Results: The γ/δ T cells of 11 of 12 patients with TA exhibited reactivity to Hsp60, whereas none of the γ/δ T cells from patients with SLE or healthy controls showed reactivity (both P < 0.001). The mean ± SD proliferative response of γ/δ T cells in patients with TA was 21.4 ± 11.3%, compared with 4.2 ± 1.2% in patients with SLE and 4.01 ±1.82% in healthy controls (both P < 0.001). In addition, compared with the control groups, the γ/δ T cells of patients with TA had increased spontaneous cytotoxicity to aortic ECs (22.1 ± 15.0% versus 9.6 ± 2.13% in SLE patients and 8.1 ± 4.7% in healthy controls; both P < 0.005), which was further enhanced following stimulation of γ/δ T cells with Hsp60. The cytotoxicity of the γ/δ T cells was significantly inhibited by treatment of these cells with concanamycin A and anti-Fas ligand-blocking antibodies.Conclusion: The results show that γ/δ T cells in patients with TA are reactive to Hsp60 and exhibit cytotoxicity to aortic ECs, suggesting a key role of Hsp60 and γ/δ T cells in the pathogenesis of TA. Takayasu arteritis (TA) is a chronic granulomatous arteritis characterized by intimal thickening, fibrosis, and stenosis as well as aneurysm of the large elastic arteries, predominantly the aorta and its major branches. Its etiology is largely unknown, but most of the available data suggest that immune-mediated dysfunction of the arterial endothelium is a primary event in the pathogenesis of the disease (1-3). We previously have demonstrated an increased number of circulating activated γ/δ T cells with a restricted T cell receptor (TCR) repertoire in patients with TA (4). Similarly, Seko et al observed the predominance of TCR-restricted γ/δ T cells in the arterial lesions of patients with TA (5). These findings indicate an antigen-driven activation and involvement of these cells in the pathogenesis of the disease. Since a major human heat-shock protein (HSP) antigenic target of γ/δ T cells is Hsp60 (6), and Hsp60/65 is highly expressed in the arterial lesions of patients with TA (7), it appears that γ/δ T cells recognize HSPs or some homologous arterial antigens and transmigrate from the circulation to the vascular wall, thus causing arterial damage that culminates in different clinical manifestations of the disease. In a recent study (8) we detected the presence of anti-endothelial cell (anti-EC) antibodies that were predominantly directed against the 60-65-kd aortic EC antigen, which was suggestive of endothelial Hsp60. These findings indicate that γ/δ T cells may react to this 60-65-kd EC antigen and lead to damage of the endothelium in TA. However, there are no data available on the reactivity of γ/δ T cells to Hsp60 and their cytotoxicity to arterial endothelium in TA. We therefore undertook this study to investigate the proliferative responses of γ/δ T cells to human Hsp60 and their cytotoxicity to human aortic ECs, as well as the mechanism of their cytotoxicity, in patients with T

Clinical and serological characterization of autoimmune hemolytic anemia in a tertiary care hospital in North India

Clinical and serological characterization of autoimmune hemolytic anemia (AIHA) helps in the diagnosis, management, and monitoring course of disease. In the present study, we serologically characterized the red-cell-bound autoantibodies in diagnosed AIHA patients with regards to antibody class, subclass, direct antiglobulin test (DAT) strength, and their correlation with in vivo hemolysis. A total of 157 samples were evaluated for DAT. Clinically and serologically, 43 of them were diagnosed as AIHA. Detailed serological characterization of autoantibodies was performed in these 43 patients using the gel technology. Hematological and biochemical parameters were obtained from the Hospital Information System. Polyspecific (immunoglobulin G (IgG)+C3) DAT-positive samples were tested for monospecific DAT (IgG, IgM, IgA, C3c, and C3d) and IgG subclass (IgG1 and IgG3). Thermal amplitude of autoantibodies was determined on eluates. Median age of the patients was 31 years (range, 12-70 years) with male to female ratio of 1:3.3. In 55.8% of patients, AIHA was secondary to an underlying disorder. Patients with strong reactive DAT had increased likelihood of hemolysis (p=0.000). IgG was the solitary autoantibody coating the red cells in 72.1% of patients. Red cells coated with multiple immunoglobulins/complements and IgG subclass IgG1 and/or IgG3 were more susceptible to undergo hemolysis. Gel technology helps the immunohematologist to diagnose and serologically characterize AIHA patient with regard to red-cell-bound autoantibodies' class, subclass, and titer as these correlate with in vivo hemolysis

Immune complex mediated vasculitis in hepatitis b and c infections and the effect of antiviral therapy

Case reports of seven patients with vasculitis and past or present viral hepatitis infection are presented, including studies on circulating immune complexes (CICs) and cryoglobulins by sucrose density gradient centrifugation or gel filtration, before and after antiviral therapy. Three patients had unusual vasculitic manifestations: coronary, large vessel, and muscle vasculitis, respectively. All the patients had high levels of CICs by the above methods, but only two had CICs by the C1q binding and conglutinin methods. The CICs/cryoglobulins contained HBV and/or HCV antibodies, antigens, and genome. The concentration of hepatitis antibodies in immune complex form was severalfold higher than in the free form in serum. In one patient, the HBs antigen was present only in the CICs and in another, only hepatitis antibodies (no antigen/genome) were present in the serum or the cryoglobulins. With antiviral therapy, six patients went into longlasting remissions. There was a temporal relationship between the regression of the vasculitic lesions and the decline in the levels of CICs/cryoglobulins

Bone marrow and blood plasma levels of IL-8 in aplastic anemia and their relationship with disease severity

Interleukin-8 (IL-8), a CXC chemokine, is also a potent inhibitor of myelopoiesis, the hematopoietic process that is severely impaired in aplastic anemia (AA). To elucidate its role in the disease, we have investigated levels of IL-8 by quantitative enzyme-linked immunosorbent assay in bone marrow and peripheral blood plasma of 27 AA patients and in the marrow of 16 controls and blood of 20 controls. Significantly increased levels of IL-8 were observed in the marrow and blood of patients as compared to controls (470.4 ± 549.6 vs. 37.5 ± 30.3; P < 0.0001) and (247.3 ± 286.3 vs. 7.9 ± 5.5; P <0.0001), respectively. Among the patients, the IL-8 levels were higher in patients with severe AA than those with nonsevere AA in the marrow (568.8 ± 586.9 vs. 126.3 ± 102.5; P < 0.005) as well as in the blood (296.6 ± 305.5 vs. 75.0 ± 84.4; P < 0.008) plasma. The marrow and blood of 74% (20/27) of the patients had increased levels of IL-8 compared to 12% (2/16; P < 0.001) and 10% (2/20, P < 0.001) of the controls, respectively. These results suggest that IL-8 may have an important role in the pathogenesis of AA

Antimonocyte antibodies in Takayasu's arteritis: prevalence of and relation to disease activity

Objective: To investigate the prevalence of antimonocyte antibodies (AMA) in Takayasu's arteritis (TA) and their relationship with disease activity. Methods: IgG-AMA were studied in the sera of 60 patients with TA (29 active disease, 31 inactive) and 43 controls by a cellular ELISA using glutaraldehyde fixed U-937 cells or peripheral blood monocytes as antigen. Relationship of AMA with disease activity was evaluated by measuring titers of these antibodies in followup sera of 15 AMA positive patients with active TA undergoing immunosuppressive therapy. Results: Twenty-six of 60 TA patients (43%) compared to 4 of 43 controls (9%) (p < 0.001) and 20 of 29 patients with active disease (69%) compared to 6 of 31 patients with inactive disease (19%) (p < 0.001) were positive for AMA. The antibody titers were significantly higher in patients with active disease than those with inactive disease (0.396 +/− 0.172 vs 0.232 +/− 0.096; p < 0.001). In the followup study of 15 patients with active disease who received immunosuppressive therapy, we observed normalization of AMA titers in 6 of the 7 patients who became inactive, compared to only one of the 8 patients whose disease remained active during followup (p < 0.01). Conclusion: AMA are present in a significant proportion of patients with TA and correlate with disease activity, suggesting a possible pathogenic role of these antibodies in TA