Cloning and characterization of Fc alpha Rb, a novel Fc alpha receptor (CD89) isoform expressed in eosinophils and neutrophils

The Fc receptor for IgA (Fc alpha R, CD89) is a transmembrane glycoprotein found on monocytes, macrophages, neutrophils, and eosinophils. Here we describe the characterization of a novel isoform of the Fc alpha R cloned from a human eosinophil cDNA library. This clone, Fc alpha Rb, lacks the exon encoding the transmembrane/intracellular region of wild type Fc alpha R, which is replaced by 23 new amino acids. Expression of Fc alpha Rb mRNA could be detected in eosinophils and neutrophils. IIA1.6 murine pro-B cells transfected with Fc alpha Rb cDNA secrete high levels of the protein, but also a substantial amount of Fc alpha Rb is expressed at the cell membrane. Membrane-bound Fc alpha Rb binds IgA-coated beads equally well as wild type Fc alpha R. Surface expression is not affected by phosphatidyl inositol phospholipase C, indicating that glycosyl phosphatidyl inositol-linkage of Fc alpha Rb is not likely. In IIA1.6 cells expressing Fc alpha Rb and FcR gamma, which is necessary for signal transduction by wild type Fc alpha R, no tyrosine phosphorylation or Ca(2+)-mobilization could be observed after receptor cross-linking. These results indicate that Fc alpha Rb is likely to have a different function than wild-type Fc alpha R receptor.     

Treatment Practices,Outcomes, and Costs of Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis,United States, 2005–2007

To describe factors associated with multidrug-resistant (MDR), including extensively-drug-resistant (XDR), tuberculosis (TB) in the United States, we abstracted inpatient, laboratory, and public health clinic records of a sample of MDR TB patients reported to the Centers for Disease Control and Prevention from California, New York City, and Texas during 2005–2007. At initial diagnosis, MDR TB was detected in 94% of 130 MDR TB patients and XDR TB in 80% of 5 XDR TB patients. Mutually exclusive resistance was 4% XDR, 17% pre-XDR, 24% total first-line resistance, 43% isoniazid/rifampin/rifabutin-plus-other resistance, and 13% isoniazid/rifampin/rifabutin-only resistance. Nearly three-quarters of patients were hospitalized, 78% completed treatment, and 9% died during treatment. Direct costs, mostly covered by the public sector, averaged $134,000 per MDR TB and $430,000 per XDR TB patient; in comparison, estimated cost per non-MDR TB patient is $17,000. Drug resistance was extensive, care was complex, treatment completion rates were high, and treatment was expensive.     

Relationship between tissue factor expression and deposition of fibrin, platelets, and leukocytes on cultured endothelial cells under venous blood flow conditions

Endothelial cell-mediated coagulation and leukocyte adhesion are processes that might be connected by the generation of thrombin. To examine the interaction of procoagulant and proadhesive activity, cultures of endothelial cells were stimulated with tumor necrosis factor-alpha, which resulted in the surface expression of tissue factor. Subsequent exposure to human nonanticoagulated blood at a shear rate of 100 s-1 in a parallel plate perfusion device led to the deposition of polymerized fibrin, which covered 63% of the endothelial surface. In addition, numerous platelet aggregates (71 per 10 mm cross- section) and leukocytes (53 +/- 6/mm2) were deposited on stimulated endothelial cells, whereas no fibrin and only a few platelet aggregates (4 +/- 1 per 10 mm cross-section) and leukocytes (6 +/- 1/mm2) were detected on control cells. A significant portion of the adherent leukocytes bound to fibrin and platelets. However, when the deposition of fibrin and platelet aggregates was inhibited with the anti-tissue factor antibody HTFI-7B8 by 100% and 86%, respectively, leukocyte adherence remained unchanged (68 +/- 6/mm2). This indicated that leukocytes could efficiently adhere to endothelial cells through direct cell-cell contact independent of both thrombin and deposited fibrin. Moreover, this direct adhesion of leukocytes to the endothelial surface was reduced twofold to threefold when fibrin deposition occurred. These data suggest a relationship between endothelial procoagulant and proadhesive properties in that tissue factor-initiated coagulation may contribute to leukocyte adhesion through the formation of an adhesive fibrin/platelet meshwork but concurrently prevents the adhesive endothelial surface to bind leukocytes at its full capacity.     

A randomized study on the effects of intramuscular injections with urinary gonadotrophins (Humegon or Pergonal) on pain, local redness and fever in infertile women opting for in-vitro fertilization

The objective of this open, multicentre, randomized controlled study in women opting for in-vitro fertilization was to compare the occurrence of pain and redness at the injection site and of post-injection fever after i.m. injection with Humegon (n = 89) or Pergonal (n = 92). Assessments were scoring of pain and redness at the injection site and of post-injection fever during the next 24 h using self-administered questionnaires. Injection site pain was reported in 48.9% of injections with Humegon and in 44.9% with Pergonal (P = 0.45). A trend was seen towards more redness after Pergonal injection (24.0 versus 15.5%; P = 0.08). Post-injection fever was reported in 1.4% with Humegon and in 1.1% with Pergonal (P = 0.80). It was concluded that there are no statistically significant differences between Humegon and Pergonal after i.m. injection with respect to the prevalence of pain and redness at the injection site and of post-injection fever.      

Risk for latent and active tuberculosis in Germany

Purpose

Few individuals that are latently infected with M. tuberculosis latent tuberculosis infection(LTBI) progress to active disease. We investigated risk factors for LTBI and active pulmonary tuberculosis (PTB) in Germany.

Methods

Healthy household contacts (HHCs), health care workers (HCWs) exposed to M. tuberculosis and PTB patients were recruited at 18 German centres. Interferon-γ release assay (IGRA) testing was performed. LTBI risk factors were evaluated by comparing IGRA-positive with IGRA-negative contacts. Risk factors for tuberculosis were evaluated by comparing PTB patients with HHCs.

Results

From 2008–2014, 603 HHCs, 295 HCWs and 856 PTBs were recruited. LTBI was found in 34.5% of HHCs and in 38.9% of HCWs. In HCWs, care for coughing patients (p = 0.02) and longstanding nursing occupation (p = 0.04) were associated with LTBI. In HHCs, predictors for LTBI were a diseased partner (odds ratio 4.39), sexual contact to a diseased partner and substance dependency (all p < 0.001). PTB was associated with male sex, low body weight (p < 0.0001), alcoholism (15.0 vs 5.9%; p < 0.0001), glucocorticoid therapy (7.2 vs 2.0%; p = 0.004) and diabetes (7.8 vs. 4.0%; p = 0.04). No contact developed active tuberculosis within 2 years follow-up.

Conclusions

Positive IGRA responses are frequent among exposed HHCs and HCWs in Germany and are poor predictors for the development of active tuberculosis.

     

Immunogenicity of Novel DosR Regulon-Encoded Candidate Antigens of Mycobacterium tuberculosis in Three High-Burden Populations in Africa

Increasing knowledge about DosR regulon-encoded proteins has led us to produce novel Mycobacterium tuberculosis antigens for immunogenicity testing in human populations in three countries in Africa to which tuberculosis (TB) is endemic. A total of 131 tuberculin skin test-positive and/or ESAT-6/CFP10-positive, human immunodeficiency virus-negative adult household contacts of active pulmonary TB cases from South Africa (n = 56), The Gambia (n = 26), and Uganda (n = 49) were tested for gamma interferon responses to 7 classical and 51 DosR regulon-encoded M. tuberculosis recombinant protein antigens. ESAT-6/CFP10 fusion protein evoked responses in >75% of study participants in all three countries. Of the DosR regulon-encoded antigens tested, Rv1733c was the most commonly recognized by participants from both South Africa and Uganda and the third most commonly recognized antigen in The Gambia. The four most frequently recognized DosR regulon-encoded antigens in Uganda (Rv1733c, Rv0081, Rv1735c, and Rv1737c) included the three most immunogenic antigens in South Africa. In contrast, Rv3131 induced the highest percentage of responders in Gambian contacts (38%), compared to only 3.4% of Ugandan contacts and no South African contacts. Appreciable percentages of TB contacts with a high likelihood of latent M. tuberculosis infection responded to several novel DosR regulon-encoded M. tuberculosis proteins. In addition to significant similarities in antigen recognition profiles between the three African population groups, there were also disparities, which may stem from genetic differences between both pathogen and host populations. Our findings have implications for the selection of potential TB vaccine candidates and for determining biosignatures of latent M. tuberculosis infection, active TB disease, and protective immunity.Tuberculosis (TB) remains an ongoing health crisis of global dimensions. The African Region has the highest incidence rate per capita (363 per 100,000 population) and includes 10 of the 22 most high-burden countries in the world (38). It has been estimated that one-third of the world''s population is latently infected with Mycobacterium tuberculosis. Human immunodeficiency virus type 1 (HIV-1)-infected individuals have a risk of about 5 to 10% per year of progression from latent infection to active TB (4), compared to 2 to 23% in a lifetime for HIV-1-seronegative individuals (24). The only currently licensed vaccine against TB is Mycobacterium bovis bacillus Calmette-Guérin (BCG), which has highly variable efficacy against adult pulmonary TB (6). The use of BCG in HIV-1-infected or -exposed infants may be contraindicated (11). The investigation of safe and effective TB vaccines is thus highly prioritized.The discovery of the precise mechanisms underlying protective anti-TB immunity calls for the identification of new biomarkers (17). A clearer understanding of which M. tuberculosis antigens evoke effective immune responses and how they are associated with protection or disease is required. Promising antigens that have been identified as immunodominant include the alpha-crystallin homologue (also known as the M. tuberculosis 16-kDa protein; Rv2031c, HspX) (9), alpha-cystallin 2 (Acr2; Rv0251) (36), Ag85A (Rv3804) (33), Hsp65 (Rv0440) (23), ESAT-6 (Rv3875) (5), and CFP10 (Rv3874) (32), some of which are currently being tested as potential TB vaccine candidates (28). The search for novel protective antigen(s) has been facilitated by expression profiling of M. tuberculosis laboratory strains cultured under conditions of hypoxia and nitric oxide stress, which are thought to resemble conditions that mycobacteria encounter in situ during latent infection (31). Voskuil et al. (35) showed that hypoxia and low concentrations of nitric oxide induced expression of a 48-gene dormancy survival regulon (DosR) believed to be associated with latency. A selection of these proteins has been tested for immunogenicity in relevant mouse models and has established the importance of the regulon in latent infection (26, 29, 34). In addition, human studies of latently M. tuberculosis-infected healthy adults living in areas where tuberculosis is not endemic have shown T-cell responses to selected DosR regulon-encoded antigens, suggesting a role in maintenance of the asymptomatic phase of latent infection (18, 30). In order to gain better insight into protection against TB and to expand our current understanding about proteins encoded by the DosR regulon that are targeted by the human immune system, we have tested 51 antigens, spanning the entire 48 genes of the DosR regulon (35), in geographically diverse human populations from three countries in Africa to which TB is endemic. Twenty-five of the antigens studied here have been tested previously (18); however, we report results with an additional 26 new antigens. The immunogenicity of the entire set of DosR regulon-encoded protein antigens in a high-TB-burden African context is described for the first time.