Recipient humoral immunity against leukoreduced allogeneic platelets is suppressed by aminoguanidine, a selective inhibitor of inducible nitric oxide synthase

Leukoreduced allogeneic platelet transfusions have been previously shown to initially stimulate an in vitro cellular cytotoxicity and subsequently Induce the formation of immunoglobulin G (IgG) antidonor alloantibodies. To further characterize these responses and determine if they are related, recipient BALB/c H-2d mice were treated with aminoguanidine (AMG), a selective inhibitor of inducible nitric oxide synthase (iNOS), and transfused weekly with 2 x 10(8) C57BL/6 H2b platelets. In control, non-AMG-treated mice, transfusion significantly (P < .01) increased serum levels of interferon-gamma (IFN-gamma) by day 1 posttransfusion (PT). IFN-gamma returned to pretransfusion levels by day 3 PT, and its production was not affected by AMG treatment. Serum interleukin-4 (IL-4), on the other hand, was undetectable before and during the transfusion protocol. By day 3 PT, recipient spleen cells could mediate in vitro anti-P815 (auto), anti-EL4 (allo), and anti-R1.1 (third-party MHC) cytotoxicity, and these responses were maximal by day 7 PT. Concurrently, a significant reduction in the vitro ability of recipient splenocytes to respond to Concanavalin A (ConA) was observed; this was not seen with lipopolysaccharide (LPS) stimulation. Elevated levels of NO2- were found in the ConA culture supernatants from transfused mice at day 3 PT. Serum antidonor alloantibodies were detected by the fifth platelet transfusion. AMG treatment of recipient mice significantly inhibited the transfusion. Induced cytotoxicity and ConA-stimulated NO2- production, and restored ConA-induced proliferation to normal levels. AMG appeared to selectively inhibit platelet-induced alloantibody production in that it did not affect antibody production induced by transfusions with 10(5) allogeneic leukocytes or by immunization with a foreign protein antigen, human gamma globulin, in adjuvant therapy. These results indicate that an in vivo AMG-sensitive mechanism is essential for recipients to initiate a humoral IgG immune response against allogeneic platelets.     

Factor XIII Val34Leu polymorphism does not contribute to the prevention of thrombotic complications in patients with antiphospholipid syndrome

The effect of thrombophilic mutations in the development of thrombosis in patients with antiphospholipid syndrome (APS) has been extensively investigated. Factor XIII (FXIII) Val34Leu polymorphism is a newly described polymorphism which is located in the three amino acids away from the thrombin activation site of the FXIII-A subunit. It has been reported that the Leu allele decreases the risk of both arterial and venous thrombosis. In the present study, we examined the association between the FXIII Val34Leu polymorphism and the development of thrombosis in patients with APS. Sixty APS patients with arterial and venous thrombosis, 22 antiphospholipid antibody (aPLA) positive patients with first trimester abortus and/or thrombocytopenia, 126 healthy controls, and 60 healthy subjects who were age- and sex-matched with thrombotic APS group were included into the study. FXIII Leu allele frequencies in the APS patients with thrombosis, aPLA-positive patients without thrombosis, healthy controls, and matched controls were 13.3, 16, 19.5, and 18.3%, respectively. When we compared Leu allele frequencies between APS patients with thrombosis and aPLA-positive patients without thrombosis, healthy controls or matched controls, we could not find any difference (chi2, p = 0.43, and P = 0.09, P = 0.67, respectively). Our results showed that the FXIII Leu allele has no protective effect in the development of thrombosis in APS.     

Hemoglobin M equon beta 41 (C7) phenylalanine leads to tyrosine

A severe hemolytic crisis was observed in a 34-yr-old female of English- Irish extraction following a viral illness treated with acetaminophen. Heinz bodies and heat instability were present only during a transient hemolytic event. A challenge dose of acetaminophen caused no detectable hematologic abnormality. Structural studies of the hemoglobin during hemolysis and again after complete recovery localized the abnormality to tryptic peptide beta Tp-5, and automated sequencing of I 125-labeled beta chains indicated a replacement of phenylalanine (C7) beta 41 by tyrosine. Substitution of the next residue, phenylalanine (CD1) beta 42 by serine (Hb Hammersmith), has resulted in chronic severe Heinz body hemolytic anemia. The lack of chronic anemia in the present disorder may reflect the different relationships of beta41 and beta 42 and/or the similarities in volume and hydrophobicity of tyrosine and phenylalanine. It is suggested that substitution of tyrosine for phenylalanine in Hb Mequon may disturb the critical environment around the heme group and render it susceptible to oxidative denaturation in the presence of infections and/or drugs.     

Transformed T lymphocytes infected by a novel isolate of human T cell leukemia virus type II

Human T cell leukemia virus type II (HTLV-II) has been isolated from a patient (Mo) with features of leukemic reticuloendotheliosis (LRE) and from a patient with acquired immunodeficiency syndrome (AIDS). We have obtained another isolate of HTLV-II from a patient (CM) with severe hemophilia A, pancytopenia, and a 14-year history of staphylococcal and candidal infections but no evidence of T cell leukemia/lymphoma, AIDS, or LRE. Fresh mononuclear cells and cultured lymphocytes from CM express retroviral antigens indistinguishable by molecular criteria from HTLV-IIMo. Leukocyte cultures from CM yield hyperdiploid (48,XY, +2, +19) continuous lymphoid lines; human fetal cord blood lymphocytes (CBL) are transformed by cocultivation with these CM cell cultures but retain normal cytogenetic constitution. Electron microscopic examination of the CM cultures and transformed CBL reveals budding of extracellular viral particles, intracellular tubuloreticular structures, and viral particles contained within intracellular vesicles. CM cell cultures and the transformed CBL do not require exogenous interleukin 2, have T cell cytochemical features and mature T helper phenotypes, and exhibit minimal T helper and profound T suppressor activity on pokeweed mitogen-stimulated differentiation of normal B cells. These characteristics, which are similar to those observed with the first HTLV-II isolate, may represent properties of all HTLV-II-infected T cells.     

Defective regulation of complement by the sickle erythrocyte: evidence for a defect in control of membrane attack complex formation

A prominent clinical manifestation of sickle cell disease (SCD) is hemolytic anemia. Although complement activation can lead to intravascular hemolysis, its role in the hemolysis of SCD is not known. Because normal red blood cells induced to vesiculate by treatment with calcium and ionophore become sensitive to damage by activated complement and because sickle cells release microvesicles as they circulate, we postulated that sickle cells might also be unusually sensitive to complement-dependent hemolysis. Complement activation is tightly regulated on the membrane of the normal erythrocyte; therefore, defective complement regulation by the sickle cell would be necessary for complement-dependent hemolysis to occur. These studies show a defect in the regulation of membrane attack complex (C5b-9) formation in sickle erythrocytes, particularly in the most dense cells. The defect is characterized by increased binding of C5b-7 and of C9 to denser sickle cells and results in increased susceptibility of sickle cells to C5b-9-mediated (reactive) lysis initiated by either C5b6 or activated cobra venom factor. Among the densest sickle cells, irreversibly sickled cells are especially sensitive to reactive lysis. The similarity of this defect to that previously described in a patient with paroxysmal nocturnal hemoglobinuria suggests that complement- mediated hemolysis could play a role in the anemia of SCD.     

5-Fluoro-uracil and low molecular weight heparin in the management of proliferative vitreo-retinopathy

Background: Proliferative vitreo-retinopathy (PVR) is the most common cause of failed repair of a primary rhegmatogenous retinal detachment (RRD). The success rates for the surgery of complicated RRD has doubled with improved vitreous techniques from 35-40% to approximately 65-75% at six months. However, despite these advances, recurrent vitreo-retinal traction leads to re-detachment in more than one-fourths of the initially successful cases. The use of adjunctive treatments to prevent cellular proliferation holds promise for the prevention of PVR or recurrences after surgery. One focus has been on the use of intra-vitreal antimetabolites to prevent the occurrence of PVR.     

Investigation of tuberculosis clusters in Dehradun city of India

ObjectiveTo investigate the presence of statistically significant geographical clusters of tuberculosis (TB) using Geographical Information System and spatial scan statistics in Dehradun, India.MethodsThe spatial scan statistic implemented with a software program, SaTScan v6.1, was used to test the presence of statistically significant spatial clusters of TB and to identify their approximate locations (P< 0.05 for primary clusters and P<0.1 for secondary clusters). Geographical Information System was used for geographical analysis.ResultsSignificant high rate spatial clusters were identified in seven wards of the Dehradun Municipal area.ConclusionsThere is sufficient evidence about the existence of statistically significant TB clusters in seven wards of Dehradun, India. The purely spatial scan statistics methodology used in this study has a potential use in surveillance of TB for detecting the true clusters of the disease.