Identification of a Mycobacterium bovis BCG auxotrophic mutant that protects guinea pigs against M. bovis and hematogenous spread of Mycobacterium tuberculosis without sensitization to tuberculin

Tuberculosis remains one of the most significant diseases of humans and animals. The only currently available vaccine against this disease is a live, attenuated vaccine, bacillus Calmette-Guérin (BCG), which was originally derived from Mycobacterium bovis and despite its variable efficacy is the most widely administered vaccine in the world. With the advent of the human immunodeficiency virus-AIDS pandemic concern has been raised over the safety of BCG. Moreover, since BCG sensitizes vaccinated individuals to the tuberculin test, vaccination with BCG prevents diagnosis of infection in vaccinated individuals. Recently, auxotrophic strains of BCG have been generated by insertional mutagenesis which have been shown to be safer than the parent BCG strain following administration to mice with severe combined immunodeficiency disease. These strains have also been shown to give comparable protection against intravenous and intratracheal challenge of BALB/c mice with M. tuberculosis relative to conventional BCG. Here we report that one of these mutants, a leucine auxotroph of BCG, conferred significant protection of the lungs and spleens of guinea pigs infected with M. bovis and protection of the spleens of guinea pigs infected with M. tuberculosis in the absence of a cutaneous hypersensitivity reaction to tuberculin. Therefore, protective immunity to tuberculosis may, at least in part, be achieved without sensitization to the tuberculin skin test. These results indicate that it may be possible to develop a new generation of vaccines based on BCG that are protective, are safe for use in the immunocompromised, and do not preclude the use of the tuberculin skin test in both humans and animals.

Vaccination of mice and cattle with plasmid DNA encoding the Mycobacterium bovis antigen MPB83

A scientific review of bovine tuberculosis in Great Britain has concluded that the development of a cattle vaccine holds the best prospect for long-term disease control. Recent reports of successful DNA vaccination against Mycobacterium tuberculosis in small animal models have raised the possibility of using a similar strategy to produce vaccines against Mycobacterium bovis infection in cattle. To test this possibility, BALB/c mice were immunized with DNA encoding the M. bovis antigen MPB83. The mice responded to vaccination with a mixed IgG1/IgG2a response to the antigen and were protected from intravenous challenge with virulent M. bovis to a similar extent as those vaccinated with bacille Calmette-Guérin. The immunogenicity of the DNA vaccine in cattle was tested, after having established that DNA encoding MPB83 was immunogenic and elicited protective immunity in mice. In these studies, vaccinated animals had strong proliferative responses to MPB83.

Development of diagnostic reagents to differentiate between Mycobacterium bovis BCG vaccination and M. bovis infection in cattle

In Great Britain a recent independent scientific review for the government has concluded that the development of a cattle vaccine against Mycobacterium bovis holds the best long-term prospect for tuberculosis control in British herds. A sine qua non for vaccination is the development of a complementary diagnostic test to differentiate between vaccinated animals and those infected with M. bovis so that test-and-slaughter-based control strategies can continue alongside vaccination. In order to assess the feasibility of developing a differential diagnostic test for a live vaccine, we chose M. bovis BCG Pasteur as a model system. Recombinant forms of antigens which are expressed in M. bovis but not, or only at low levels, in BCG Pasteur (ESAT-6, MPB64, MPB70, and MPB83) were produced. These reagents were tested either alone or in combination by using peripheral blood mononuclear cells from M. bovis-infected, BCG-vaccinated, and Mycobacterium avium-sensitized calves. All four antigens induced in vitro proliferation and gamma interferon responses only in M. bovis-infected animals. A cocktail composed of ESAT-6, MPB64, and MPB83 identified infected animals but not those vaccinated with BCG. In addition, promiscuous T-cell epitopes of ESAT-6, MPB64, and MPB83 were formulated into a peptide cocktail. In T-cell assays with this peptide cocktail, infected animals were identified with frequencies similar to those obtained in assays with the protein cocktail, while BCG-vaccinated or M. avium-sensitized animals did not respond. In summary, our results suggest that peptide and protein cocktails can be designed to discriminate between M. bovis infection and BCG vaccination.

Federal law and the accommodation of students with LD: the lawyers' look at the BU decision

This article explores the genesis and development of the Guckenberger v. Boston University case, detailing the pertinent facts and issues of the case and analyzing the court's decision. The overall question posed by the case (as considered from the perspective of the plaintiffs' attorneys) was whether Boston University violated federal law in its response to the requests for reasonable accommodations by students with learning disabilities. The article quotes primarily from the decision issued by Federal Judge Patti Saris. The court's decision signified an important development in the field of higher education and set an extraordinary precedent in favor of students with disabilities under both the Americans with Disabilities Act and the Rehabilitation Act of 1973.

Cytokines in detoxified patients with chronic alcoholism without liver disease: increased monocytic cytokine production

BACKGROUND

The aim of the present study was to examine the production of interferon-gamma, tumor necrosis factor-alpha (TNF-alpha), granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-6 (IL-6), IL-10, IL-4, IL-5, IL-1 receptor antagonist (IL-1RA), and prostaglandin E2 in relation to the number of leukocytes in the blood of detoxified, chronic alcoholic patients without apparent liver disease (AWLD).

METHODS

Phytohemagglutinin + lipopolysaccharide-induced production of the above variables as well as the number of white blood cells and differentials were determined in detoxified AWLD patients and normal volunteers.

RESULTS

Detoxified AWLD patients have a significantly higher production of IL-6, IL-10, TNF-alpha, GM-CSF, and IL-1RA and significantly increased numbers of leukocytes and neutrophils compared to normal volunteers.

CONCLUSIONS

Detoxified AWLD patients show an increased production of proinflammatory cytokines, i.e., IL-6, TNF-alpha, and GM-CSF, as well as negative immunoregulatory proteins, such as IL-10 and IL-1RA.

Identification of common epitopes on gliadin, enterocytes, and calreticulin recognised by antigliadin antibodies of patients with coeliac disease

BACKGROUND

Sera of patients with coeliac disease, containing IgA and IgG antigliadin antibodies (AGA) and various IgA autoantibodies, react with isolated enterocytes. AGA cross react with enterocyte antigens, one of which has been identified as calreticulin.

AIMS

To characterise the antigenic structures of gliadin, enterocytes, and calreticulin recognised by AGA from patients with active coeliac disease.

METHODS

AGA were isolated from sera of nine patients by affinity chromatography and tested by competitive ELISA using 40 alpha-gliadin synthetic dodecapeptides (A1-F6).

RESULTS

Reactivity of gliadin with all purified AGA tested was inhibited by peptide A4 at the N-terminal region; by C2, C3, and D4 at the central region; and by F3 and F4 at the C-terminal region of the gliadin molecule. AGA cross reactivity with enterocytes was inhibited by peptides A4, D1-D4, and F6 and with calreticulin by peptides A4, D3, and D4. As dominant epitopes AGA of coeliac patients recognise similar structures corresponding to peptides A4, D3, D4, and F6 present on gliadin, enterocytes, and calreticulin. Substitution of glutamine in the A4 peptide by glutamic acid caused loss of inhibitory capacity. Shortening of peptide A4 on the N-terminal by three amino acids increased its inhibitory effect.

CONCLUSIONS

AGA of patients with coeliac disease react with similar structures on gliadin and potential autoantigens on enterocytes.

Alterations in immune functions during normal aging and Alzheimer's disease

It is thought that aging induces immune changes, which are related to the pathophysiology of Alzheimer's disease (DAT). In this study, the total number of leukocytes, white blood cell differentiation, mitogen-induced lymphocytic proliferation, neutrophil phagocytosis and superoxide release, and prostaglandin E2 (PGE2) production by mitogen-stimulated whole blood cultures were comparatively investigated between healthy adults (range 22-45 years) and healthy elderly volunteers (range 70-91 years), and between DAT patients (range 56-94 years) and age-matched control subjects. Healthy elderly volunteers showed significantly lower phytohemagglutinin (PHA)-induced lymphocyte proliferation and percentage and absolute number of basophils than young volunteers. In normal volunteers, there were significant and negative correlations between age and the number of basophils. Patients with DAT showed a trend toward significantly higher PHA-induced lymphocyte proliferation and significantly decreased percentage and absolute number of large unstained cells than healthy volunteers. In DAT patients, the total number of leukocytes and the percentage and number of neutrophils were positively correlated with age. All other immune-inflammatory variables were not significantly altered either by the aging process or DAT. The present study suggests that aging and DAT may differently affect some immune variables.

Babies and bathwater: the case for evaluation in maternity services

Evaluation of publicly funded services is an issue of accountability but also of continuous improvement. In health care services, the users can be adversely affected by poor services and the financial, psychosocial and physical costs can be enormous. It is increasingly important that evaluation be targeted at decreasing health inequalities so that the widening gap between the wealthy and poor can be reduced. The provision of maternity services in western countries has changed over the past few decades and is an excellent case study of the importance of evaluation and evidence-based research. This paper discusses the general context of changes to maternity services and briefly reports on a comparative study of low-risk women choosing birth centre or traditional labour ward care.

Diagnosis of gluten-sensitive enteropathy: is exclusive reliance on histology appropriate?

OBJECTIVE

Coeliac disease is a prevalent disorder but frequently remains undiagnosed because of varied modes of clinical presentation. In this study, methods for the detection of coeliac disease were evaluated in a clinical practice setting.

METHODS

Small intestinal histology, IgA anti-endomysial and IgG anti-gliadin antibody tests were performed on 441 unselected, consecutive patients under investigation for small intestinal disease. Response to treatment and other clinical events were monitored over the ensuing years.

RESULTS

Untreated coeliac disease was diagnosed in 97 patients and was excluded in 344. At clinical presentation, the endomysial antibody test was positive in 84 of the 97 untreated coeliac patients (sensitivity 87%) and negative in 340 of the 344 non-coeliac patients (specificity 99%). A typical histological lesion was found in 83 of the 97 coeliac patients (sensitivity 86%) but was absent in all 344 non-coeliacs (specificity 100%). The sensitivity of the gliadin antibody test was 69% and the specificity was 71%.

CONCLUSIONS

In unselected patients attending a gastroenterology clinic, small bowel histology and endomysial antibody serology show similar predictive value in the diagnosis of coeliac disease. These results emphasize that a combination of clinical, histological and serological criteria are required for effective diagnosis of this disorder. Exclusive reliance on histology or serology will result in failure to make a diagnosis in a significant proportion of patients.

The inflammatory response system and the availability of plasma tryptophan in patients with primary sleep disorders and major depression

BACKGROUND

It is now well established that major depression is accompanied by an immune-inflammatory system response and that indicators of the latter are inversely correlated with lower availability of plasma tryptophan in depression. Inflammation and infection can alter sleep architecture, whereas sleep disturbances can impair immune functions.

AIMS AND METHODS

The aims of the present study were to examine: (i) immune-inflammatory markers, i.e. serum interleukin-6 (IL-6), IL-8, IL-6 receptor (IL-6R), IL-1R antagonist (IL-1RA), gp130, and prostaglandin E2 (PGE2) production by mitogen-stimulated whole blood and the availability of plasma tryptophan in patients with primary sleep disorders, major depression and healthy volunteers; and (ii) the relationships between the availability of tryptophan and indicators of the immune-inflammatory response system.

RESULTS

Mitogen-stimulated release of PGE2, and serum IL-6 and IL-8, were significantly increased in both depressed and sleep disordered patients compared to normal controls. Serum IL-1RA was significantly higher in depressed patients than in normal controls. Patients with depression and sleep disorders had a significantly lower availability of tryptophan than normal controls. There were significant and inverse relationships between the availability of plasma tryptophan and serum IL-1RA, IL-6 and IL-8.

CONCLUSIONS

The results suggest that (i) there is an activation of the immune-inflammatory response system in primary sleep disorders and depression; and (ii) the decreased availability of plasma tryptophan may be related to the inflammatory system response.

Correlation of platelet Fc gammaRIIA polymorphism in refractory idiopathic (immune) thrombocytopenic purpura

Fc gammaRIIA, a low affinity receptor for IgG, is a polymorphic molecule: Fc gammaRIIA-HH131, Fc gammaRIIA-HR131 and Fc gammaRIIA-RR131. This polymorphism influences the efficiency of the receptor to bind with IgG2. Recent reports on altered distribution amongst individuals with heparin-induced thrombocytopenia (HIT) prompted us to examine the Fc gammaRIIA polymorphism in a cohort of patients with refractory idiopathic (immune) thrombocytopenic purpura (ITP), in whom severe disease had required them to undergo splenectomy. 29 post splenectomy ITP individuals and 61 normal controls were investigated. Polymerase chain reaction (PCR) and a Southern blotting technique were used to determine the Fc gammaRII polymorphism. Although the distribution of the allotypes of Fc gammaRIIA in the control population was similar to that found in other European studies of Caucasian populations (15 (25%) HH131; 35 (57%) HR131; 11 (18%) RR131), the patient group was skewed towards the RR131 allotype which has least efficiency for IgG2 binding (3 (10%) HH131; 12 (42%) HR131; 14 (48%) RR131; P<0.005). These findings suggest that Fc gammaRIIA polymorphisms may be implicated in the pathophysiology of ITP or may be responsible for modulating the immune response in this heterogeneous autoimmune disease.

Endomysial antibody detection using human umbilical cord tissue as substrate: reactivity of cells in Wharton's jelly

The measurement of immunoglobulin A (IgA) endomysial antibodies is now established as an important diagnostic test in gluten-sensitive disease. Monkey oesophagus is the commonly used tissue substrate, but it has been proposed that human umbilical cord tissue may be a suitable alternative for antibody detection. In this study, we report a modified method of examining endomysial antibody reactivity with cord tissue. This involves examination of antibody reactivity with cells in Wharton's jelly, and with umbilical cord blood vessel. A total of 370 patients being investigated for coeliac disease were studied and this diagnosis was established in 42. Endomysial antibodies were found in all 42 using umbilical cord tissue, and the test results were confirmed with monkey oesophagus substrate. In three of the remaining 328 non-coeliacs, a false-positive endomysial antibody test was noted and small intestine histology was normal in these patients. All positive sera were found to react with cells in Wharton's jelly, and reticular staining of blood vessels was also present. Examination for immunofluorescence in both Wharton's jelly and blood vessel components of cord tissue greatly simplified test interpretation.

Promoting successful breast feeding among women with a low income

OBJECTIVE

To identify those factors which promote or discourage successful breast feeding in a sample of women with a low income.

DESIGN

Qualitative research using in-depth, semi-structured interviews.

SAMPLE

All women with a low income who were identified as having breast fed their latest baby at least once and who had delivered at a district general hospital in the south west of England from 17 September 1996 to 5 February 1997.

FINDINGS

Three behavioural areas which determined whether or not women with a low income continued to breast feed were identified: individual and social environmental, baby and midwifery practice factors. In terms of individual and social environmental factors those women who continued to breast feed were more likely to have: positive attitudes; realistic expectations; greater levels of self-esteem; a supportive mother/friend; a partner who was not against breast feeding; and the ability to cope with the perceived temporary social isolation. In terms of baby factors those women who continued to breast feed had babies who were more likely to: have three- or four-hourly feeds; be perceived as a contented baby; and have gained weight. And finally, in terms of midwifery practice factors, those women who continued to breast feed were more likely to have: not been separated from their baby; not been given supplementary or complementary feeds; received good advice, especially with regard to positioning the baby at the breast; had greater continuity of midwifery input; had sufficient quality time with a midwife; and had the opportunity to solve problems with a community midwife's help.

IMPLICATIONS FOR PRACTICE

Midwifery practice can be improved to promote successful breast feeding among women with a low income by: 1) creating realistic expectations and increasing women's confidence/desire to succeed in breast feeding; 2) providing good quality advice and support to mothers of newborn babies, particularly with regard to positioning the baby at the breast; 3) improving social-support networks available to breast-feeding mothers, perhaps through educating grandmothers (or partners) in breast-feeding matters.

Endomysium: autoantigen in coeliac disease

In coeliac disease, dietary exposure to gluten is associated with an autoimmune response to gastrointestinal antigens, including endomysium. Measurement of autoantibodies to endomysium is a highly specific and sensitive method of diagnosing coeliac disease. Analysis of the interaction between gluten and endomysium should provide a critical insight into the pathogenesis of this condition.

Beta-2-microglobulin, neopterin and monocyte Fc gamma receptors in opportunistic infections of HIV-positive patients

The aim of this study was to examine serum and cellular markers of immune activation in HIV-positive (HIV+) patients with and without current opportunistic infections. Fc gamma receptor (Fc gamma R) expression on monocytes, serum neopterin and beta-2-microglobulin were studied. Thirty HIV+ patients (grouped according to Centers for Disease Control (CDC) classification) were studied and compared with 27 normal blood donor controls. HIV+ patients were further separated into three groups: 2 (CDC II), 3 (CDC III/IV without infections) and 4 (CDC III/IV with current infections). Eleven of the patients had current opportunistic infections. Results indicate that beta-microglobulin, neopterin, fc gamma RI, Fc gamma RII and Fc gamma III were significantly increased in HIV+ patients compared to controls. Further analysis of the data using Tukey-Kramer all pairwise comparison revealed that for beta-2-microglobulin the mean values for patients in groups 2, 3 and 4 were significantly different (P < 0.0001). Serum neopterin levels and the percentage of CD14+14+ monocytes expressing Fc gamma RIII showed significant differences in the mean values of group 2 and group 4; similarly, for CD4+ lymphocyte counts group 2 and group 4 were significantly different. These results indicated that beta-2-microglobulin, neopterin and CD14+ monocyte Fc gamma RIII are increased particularly in HIV+ patients with current opportunistic infections while CD4+ lymphocyte counts are reduced. The results suggest that these markers, particularly beta-2-microglobulin, could be useful indicators of the inflammatory process associated with opportunistic infection at later stages of disease where other laboratory markers may be atypical.

Human umbilical vein endothelial cells: a new easily available source of endomysial antigens

OBJECTIVE

To evaluate human umbilical vein endothelial cells (HUVEC) as an alternative source of endomysial antigen (EmAg) and to assess their suitability for the detection of endomysial antibodies (EmA) in coeliac disease (CD).

METHODS

HUVEC were reacted on glass slides with patient sera and examined by fluorescent microscopy. Flow cytometry was used to determine whether the EmAg was expressed on the surface of the cells or was intracellular. Absorption studies were used to confirm the specificity of results.

RESULTS

The data presented here show that HUVEC contain an intracellular antigen that binds to immunoglobulin A (IgA) from patients with active CD. Correlation studies showed that HUVEC antibodies were present in the sera of all patients that contained EmA and reticulin IgA antibodies whereas reticulin antibodies were only present in 24 of the 31 patients who were either EmA or HUVEC positive. All of the sera tested which were negative for EmA were also negative for HUVEC antibodies. Ten patients with Crohn's disease and 10 patients with ulcerative colitis were negative for HUVEC or EmA reactivity, as were 16 control subjects attending the gastroenterology clinic with non-specific symptoms and normal small intestinal biopsies.

CONCLUSIONS

These findings suggest that the antigen found in HUVEC is antigenically similar to that found in reticulin and endomysium and that all three antigens may be the same. In contrast to the monkey oesophagus, HUVEC offer an easily available antigen for the serological diagnosis of coeliac disease.

Increased numbers of CD5+ B cells and T cell receptor (TCR) gamma delta+ T cells are associated with younger age of onset in rheumatoid arthritis (RA)

Patients presenting with RA before the age of 45 years (younger onset) are known to have more aggressive disease compared with patients presenting after the age of 65 years (older onset). Coordinated expansion of circulating CD5+ B cell and TCR gamma delta+ T cell levels has been reported in patients with RA. This study assesses the peripheral blood levels of these two cell types in RA patients with younger and older onset of disease. CD5+ B cell levels were significantly elevated in the younger onset RA group (26.6+/-4.5%) compared with the older onset RA group (14.2+/-1.2%; P<0.01). TCR gamma delta+ T cell levels were also significantly raised in the young patients (4.0+/-0.9%) compared with elderly patients (1.6+/-0.2%; P<0.01). T cell levels (CD3+) were similar in both groups (young 66.4+/-3.3%; old 74.3+/-3.4% (mean+/-s.e.m.); NS). Total B cell levels (CD19+) were also similar in these groups (7.7+/-0.7% versus 8.9+/-1.8%; NS). A significant positive correlation was observed between the CD5+ B and TCR gamma delta+ T cell types in the patients (r=0.72, P<0.05). Compared with age-matched normal controls, the younger onset patients had similar CD5+ B cell and TCR gamma delta+ T cell levels to the elderly controls (CD5+ B cells 30.2+/-3.0%; TCR gamma delta+ T cells 3.0+/-0.8%). Conversely, older onset RA patients had CD5+ B cell levels similar to the young controls (12.3+/-1.9%). Spontaneous in vitro synthesis of immunoglobulins (IgM, IgA and IgG) and rheumatoid factors (IgM and IgA isotypes) were not significantly different in both patient groups. The coordinate expansion of circulating CD5+ B cells and gamma delta+ T cells seen in patients with RA presenting before 45 years of age and not after 65 years of age may suggest a potential role for these cells in more aggressive disease states.

Increased expression of Fc gamma receptors on neutrophils and monocytes may reflect ongoing bacterial infection

The Fc gammaR receptors for IgG, Fc gammaRI, Fc gammaRII and Fc gammaRIII were measured on neutrophils and monocytes from 36 patients suspected of systemic infection. These results were compared with 30 blood donor controls to assess the level of expression as an early indicator of bacterial infection. Fc gammaRI expression on neutrophils was found to be significantly increased from patients with systemic or localised infections, when compared to non-infected patient group, i.e., patients with no cultural evidence of bacterial infections, (p=0.02, p=0.04) or normal controls (p<0.0001, p=0.0005). Fc gammaRI expression on monocytes was also significantly increased in both of the infected groups compared to normal controls (p<0.0001, p=0.001); however, no significant difference could be seen when compared with the non-infected patients. Fc gammaRIII was found to be significantly increased on a subset of monocytes in patients with systemic or localised infections compared to the non-infected group (p=0.009, p=0.006) and compared to the normal controls (p=0.009, p=0.003). Infections caused by gram-negative bacilli induced a higher Fc gammaR response than infection with either streptococci or staphylococci. These data suggest that the measurement of Fc gammaRI on neutrophils and Fc gammaRIII on monocytes may be a useful rapid indicator of bacterial infection.

Secretion of the mycobacterial 19-kilodalton protein by Escherichia coli, a novel method for the purification of recombinant mycobacterial antigens

We have reported previously (R.G. Hewinson and W.P. Russell, J. Gen. Microbiol. 139:1253-1259, 1993) the secretion by Escherichia coli of a recombinant form of the immunogenic protein MPB70 of Mycobacterium bovis when the protein is translated from its native initiation codon. N-terminal sequence analysis of the purified protein revealed that the signal peptide of MPB70 was cleaved by an endopeptidase of E. coli at the same cleavage site as reported for the protein in M. bovis. Since both the B- and T-cell antigenicities of the purified recombinant protein were similar to that of the native protein, the 19-kDa antigen of M. bovis was used as a model to test whether the signal peptide of MPB70 could direct the secretion of heterologous proteins in E. coli and whether antigen produced in this way retained antigenicity superior to that of recombinant protein produced as a fusion to glutathione-S-transferase. A chimeric protein was produced in which the signal peptide of MPB70 was fused to the 19-kDa antigen of M. bovis at amino acid residue 23. This chimeric protein was found to be secreted into the periplasm and culture medium of recombinant E. coli, and the signal peptide was cleaved by an endopeptidase of E. coli during secretion. Secretion of the 19-kDa antigen facilitated purification of the antigen by two-stage preparative electrophoresis which gave yields of 2.5 mg of purified, soluble 19-kDa antigen from 2.5 g (wet weight) of E. coli. Antigen purified in this way retained both B- and T-cell antigenicities. Moreover, the nonspecific mitogenic activity of the purified 19-kDa antigen was low, while the magnitude of the T-cell response induced by the purified antigen was considerably higher than that observed with purified antigen produced as a fusion protein with glutathione-S-transferase.