The effectiveness of enzymic irrigation in removing a nutrient-stressed endodontic multispecies biofilm.

AIM: To establish a nutrient-stressed multispecies model biofilm and investigate the dynamics of biofilm killing and disruption by 1% trypsin and 1% proteinase K with or without ultrasonic activation. METHODOLOGY: Nutrient-stressed biofilms (Propionibacterium acnes, Staphylococcus epidermidis, Actinomyces radicidentis, Streptococcus mitis and Enterococcus faecalis OMGS 3202) were grown on hydroxyapatite discs and in prepared root canals of single-rooted teeth in modified fluid universal medium. The treatment groups included trypsin, proteinase K, 0.2% chlorhexidine gluconate and 1% sodium hypochlorite (NaOCl) (with and without ultrasonics). NaOCl and chlorhexidine were the positive controls and untreated group, and sterile saline was the negative control. The biofilms were investigated using confocal laser scanning microscopy (CLSM) with live/dead staining and quantitative microbial culture. RESULTS: Nutrient stress in the multispecies biofilm was apparent as the medium pH became alkaline, glucose was absent, and serum proteins were degraded in the supernatant. The CLSM showed the percentage reduction in viable bacteria at the biofilm surface level due to nutrient starvation. On the disc model, trypsin and proteinase K were effective in killing bacteria; their aerobic viable counts were significantly lower (P < 0.01) than the negative control and chlorhexidine. NaOCl was the most effective agent (P < 0.001). In the tooth model, when compared to saline, trypsin with ultrasonics caused significant killing both aerobically and anaerobically (P < 0.05). Chlorhexidine (1.46 ± 0.42), trypsin (3.56 ± 1.18) and proteinase K (4.2 ± 1.01) with ultrasonics were significantly effective (P < 0.05) in reducing the substratum coverage as compared to saline with ultrasonics (12% ± 4.9). CONCLUSION: Trypsin with ultrasonic activation has a biofilm killing and disrupting potential.

Modified vaccinia virus Ankara-based vaccine vectors induce apoptosis in dendritic cells draining from the skin via both the extrinsic and intrinsic caspase pathways, preventing efficient antigen presentation.

Dendritic cells (DC) are potent antigen-presenting cells and central to the induction of immune responses following infection or vaccination. The collection of DC migrating from peripheral tissues by cannulation of the afferent lymphatic vessels provides DC which can be used directly ex vivo without extensive in vitro manipulations. We have previously used bovine migrating DC to show that recombinant human adenovirus 5 vectors efficiently transduce afferent lymph migrating DEC-205(+) CD11c(+) CD8(-) DC (ALDC). We have also shown that recombinant modified vaccinia virus Ankara (MVA) infects ALDC in vitro, causing downregulation of costimulatory molecules, apoptosis, and cell death. We now show that in the bovine system, modified vaccinia virus Ankara-induced apoptosis in DC draining from the skin occurs soon after virus binding via the caspase 8 pathway and is not associated with viral gene expression. We also show that after virus entry, the caspase 9 pathway cascade is initiated. The magnitude of T cell responses to mycobacterial antigen 85A (Ag85A) expressed by recombinant MVA-infected ALDC is increased by blocking caspase-induced apoptosis. Apoptotic bodies generated by recombinant MVA (rMVA)-Ag85A-infected ALDC and containing Ag85A were phagocytosed by noninfected migrating ALDC expressing SIRPα via actin-dependent phagocytosis, and these ALDC in turn presented antigen. However, the addition of fresh ALDC to MVA-infected cultures did not improve on the magnitude of the T cell responses; in contrast, these noninfected DC showed downregulation of major histocompatibility complex class II (MHC-II), CD40, CD80, and CD86. We also observed that MVA-infected ALDC promoted migration of DEC-205(+) SIRPα(+) CD21(+) DC as well as CD4(+) and CD8(+) T cells independently of caspase activation. These in vitro studies show that induction of apoptosis in DC by MVA vectors is detrimental to the subsequent induction of T cell responses.

Differential effects of viral vectors on migratory afferent lymph dendritic cells in vitro predict enhanced immunogenicity in vivo.

Targeting dendritic cells (DC) is key to driving effective immune responses. Lymphatic cannulation provides access to the heterogeneous populations of DC draining peripheral sites in rodents and ruminants. Afferent lymph DEC-205(+) CD11c(+) SIRPα(+) DC were preferentially infected ex vivo with three vaccine viral vectors: recombinant human replication-defective human adenovirus 5 (rhuAdV5), recombinant modified vaccinia virus Ankara (rMVA), and recombinant fowlpox virus (rFPV), all expressing green fluorescent protein (GFP). The rhuAdV5-infected cells remained viable, and peak GFP expression was observed 16 to 24 h posttransduction. Increasing the incubation period of DC with rhuAdV5 enhanced GFP expression. In contrast, DC infected with rMVA-GFP or rFPV-GFP became rapidly apoptotic and GFP expression peaked at 6 h postinfection. Delivery of foot-and-mouth disease virus (FMDV) A(22) antigen to DC by rhuAdV5-FMDV-A(22) ex vivo resulted in significantly greater CD4(+) T cell proliferation than did delivery by rFPV-FMDV-A(22). Delivery of rhuAdV5-GFP in oil adjuvant in vivo, to enhance DC-vector contact, resulted in increased GFP expression in migrating DC compared to that with vector alone. Similarly, CD4(+) T cell responses were significantly enhanced when using rhuAdV5-FMDV-A(22) in adjuvant. Therefore, the interaction between viral vectors and afferent lymph DC ex vivo can predict the outcome of in vivo immunization and provide a means of rapidly assessing the effects of vector modification.

Substantially reduced pre-patent parasite multiplication rates are associated with naturally acquired immunity to Plasmodium falciparum.

Naturally acquired immunity to Plasmodium falciparum's asexual blood stage reduces parasite multiplication at microscopically detectable densities. The effect of natural immunity on initial prepatent parasite multiplication during the period following a new infection has been uncertain, contributing to doubt regarding the utility of experimental challenge models for blood-stage vaccine trials. Here we present data revealing that parasite multiplication rates during the initial prepatent period in semi-immune Gambian adults are substantially lower than in malaria-naive participants. This supports the view that a blood-stage vaccine capable of emulating the disease-reducing effect of natural immunity could achieve a detectable effect during the prepatent period.

Altered peptide ligands narrow the repertoire of cellular immune responses by interfering with T-cell priming.

Variation in epitopes of infectious pathogens inhibits various effector functions of T lymphocytes through antagonism of the T-cell receptor. However, a more powerful strategy for immune evasion would be to prevent the induction of T-cell responses. We report here mutual 'interference' with the priming of human T-cell responses by a pair of naturally occurring variants of a malaria cytotoxic T-cell epitope. Interference with priming also occurs in vivo for a murine malaria T-cell epitope. Reshaping of the T-cell repertoire by such immune interference during naive T-cell induction may provide a general mechanism for observed patterns of immunodominance and persistence by many polymorphic pathogens.

Enhanced immunogenicity for CD8+ T cell induction and complete protective efficacy of malaria DNA vaccination by boosting with modified vaccinia virus Ankara.

Immunization with irradiated sporozoites can protect against malaria infection and intensive efforts are aimed at reproducing this effect with subunit vaccines. A particular sequence of subunit immunization with pre-erythrocytic antigens of Plasmodium berghei, consisting of single dose priming with plasmid DNA followed by a single boost with a recombinant modified vaccinia virus Ankara (MVA) expressing the same antigen, induced unprecedented complete protection against P. berghei sporozoite challenge in two strains of mice. Protection was associated with very high levels of splenic peptide-specific interferon-gamma-secreting CD8+ T cells and was abrogated when the order of immunization was reversed. DNA priming followed by MVA boosting may provide a general immunization regime for induction of high levels of CD8+ T cells.

New candidate vaccines against blood-stage Plasmodium falciparum malaria: prime-boost immunization regimens incorporating human and simian adenoviral vectors and poxviral vectors expressing an optimized antigen based on merozoite surface protein 1.

Although merozoite surface protein 1 (MSP-1) is a leading candidate vaccine antigen for blood-stage malaria, its efficacy in clinical trials has been limited in part by antigenic polymorphism and potentially by the inability of protein-in-adjuvant vaccines to induce strong cellular immunity. Here we report the design of novel vectored Plasmodium falciparum vaccines capable of overcoming such limitations. We optimized an antigenic insert comprising the four conserved blocks of MSP-1 fused to tandemly arranged sequences that represent both allelic forms of the dimorphic 42-kDa C-terminal region. Inserts were expressed by adenoviral and poxviral vectors and employed in heterologous prime-boost regimens. Simian adenoviral vectors were used in an effort to circumvent preexisting immunity to human adenoviruses. In preclinical studies these vaccines induced potent cellular immune responses and high-titer antibodies directed against MSP-1. The antibodies induced were found to have growth-inhibitory activity against dimorphic allelic families of P. falciparum. These vectored vaccines should allow assessment in humans of the safety and efficacy of inducing strong cellular as well as cross-strain humoral immunity to P. falciparum MSP-1.

Global evolutionary trend of the prevalence of primary glomerulonephritis over the past three decades.

OBJECTIVE: The prevalence of primary glomerulonephritis in Singapore is compared with that of 28 other countries to review changing trends in the evolution of primary glomerulonephritis in Asia and other countries. METHOD: 2,586 renal biopsies in Singapore over the past 3 decades were reviewed and compared with data from 28 other countries. RESULTS: In the 1st decade most Asian countries have mesangial proliferative glomerulonephritis as the most common form of primary glomerulonephritis, and in the 3rd decade there has been a dramatic increase in focal and segmental glomerulosclerosis reflecting aging and obesity in keeping with more developed countries. IgA nephritis remains the commonest glomerulonephritis in many countries. Membranous glomerulonephritis continues to be more prevalent in Western countries while mesangial proliferative glomerulonephritis remains prevalent in many Asian countries. CONCLUSION: Apart from geographical and genetic influences, socioeconomic factors may play a role in the evolution of the biopsy pattern in some countries. Worldwide, the prevalence of focal segmental glomerulosclerosis continues to increase. In third world countries some of the commoner forms of glomerulonephritis are related to infections, in contrast to developed countries where the antigenic exposure may be related to diet, allergens and other industrial agents.

Single-dose protection against Plasmodium berghei by a simian adenovirus vector using a human cytomegalovirus promoter containing intron A.

Human adenovirus serotype 5 (AdH5) vector vaccines elicit strong immune responses to the encoded antigen and have been used in various disease models. We designed AdH5 vectors expressing antigen under the control of a human cytomegalovirus (HCMV) immediate-early promoter containing its intron A sequence. The transcriptional levels of antigen and immune responses to antigen for vectors with the HCMV promoter with the intron A sequence (LP) were greater than those for AdH5 vectors using the HCMV promoter sequence without intron A (SP). We compared an E1E3-deleted AdH5 adenoviral vector, which affords more space for insertion of foreign sequences, and showed it to be as immunogenic as an E1-deleted AdH5 vector. Neutralizing antibodies to AdH5 limit the efficacy of vaccines based on the AdH5 serotype, and simian adenoviral vectors offer an attractive option to overcome this problem. We constructed E1E3-deleted human and simian adenoviral vectors encoding the pre-erythrocytic-stage malarial antigen Plasmodium berghei circumsporozoite protein. We compared the immunogenicity and efficacy of AdC6, a recombinant simian adenovirus serotype 6 vector, in a murine malaria model to those of AdH5 and the poxviral vectors MVA and FP9. AdC6 induced sterile protection from a single dose in 90% of mice, in contrast to AdH5 (25%) and poxviral vectors MVA and FP9 (0%). Adenoviral vectors maintained potent CD8(+) T-cell responses for a longer period after immunization than did poxviral vectors and mainly induced an effector memory phenotype of cells. Significantly, AdC6 was able to maintain protection in the presence of preexisting immunity to AdH5.

Association of malaria parasite population structure, HLA, and immunological antagonism.

Host-parasite coevolution has been likened to a molecular arms race, with particular parasite genes evolving to evade specific host defenses. Study of the variants of an antigenic epitope of Plasmodium falciparum that induces a cytotoxic T cell response supports this view. In African children with malaria, the variants present are influenced by the presence of a human leukocyte antigen (HLA) type that restricts the immune response to this epitope. The distribution of parasite variants may be further influenced by the ability of cohabiting parasite strains to facilitate each other's survival by down-regulating cellular immune responses, using altered peptide ligand antagonism.

The isolation of bifidobacteria from occlusal carious lesions in children and adults.

The aim of this study was to enumerate and identify bifidobacteria from occlusal carious lesions in permanent and deciduous teeth. Samples of infected dentine were obtained from 24 active occlusal lesions in deciduous teeth and from 15 occlusal lesions in permanent teeth. Plaque samples from sound occlusal surfaces of 12 caries-free adults and 12 children were also obtained. The bifidobacterial strains were isolated in mupirocin-containing selective media, Gram-stained and subcultured for identification. Total bacterial counts were determined using fastidious anaerobic agar, and isolates were identified using genus-specific PCR primers and were confirmed by 16S rRNA sequencing. Bifidobacteria were isolated from 13 of the 15 occlusal lesions in the adults and formed 5.09 +/- 2.11% of the total cultivable flora. In the children, bifidobacteria were isolated from 16 of the 24 occlusal lesions and formed 7.4 +/- 2.6% of the total flora. No bifidobacteria were isolated from the occlusal surfaces of caries-free adults or children. A total of 424 bifidobacteria were identified and these were Bifidobacteriumdentium, Parascardovia denticolens, Scardoviainopicata, Bifidobacterium longum, Scardovia genomosp. C1 and Bifidobacterium breve. B. dentium was present in 14 out of the 16 bifidobacteria-positive samples from the lesions on the deciduous teeth and in 7 out of the 13 positive lesions in adults (p = 0.04). The present data suggest that bifidobacteria may play a role in the progression of occlusal caries lesions in both children and adults.

Heterologous Two-Dose Vaccination with Simian Adenovirus and Poxvirus Vectors Elicits Long-Lasting Cellular Immunity to Influenza Virus A in Healthy Adults.

BACKGROUND: T-cell responses against highly conserved influenza antigens have been previously associated with protection. However, these immune responses are poorly maintained following recovery from influenza infection and are not boosted by inactivated influenza vaccines. We have previously demonstrated the safety and immunogenicity of two viral vectored vaccines, modified vaccinia virus Ankara (MVA) and the chimpanzee adenovirus ChAdOx1 expressing conserved influenza virus antigens, nucleoprotein (NP) and matrix protein-1 (M1). We now report on the safety and long-term immunogenicity of multiple combination regimes of these vaccines in young and older adults. METHODS: We conducted a Phase I open-label, randomized, multi-center study in 49 subjects aged 18-46years and 24 subjects aged 50years or over. Following vaccination, adverse events were recorded and the kinetics of the T cell response determined at multiple time points for up to 18months. FINDINGS: Both vaccines were well tolerated. A two dose heterologous vaccination regimen significantly increased the magnitude of pre-existing T-cell responses to NP and M1 after both doses in young and older adults. The fold-increase and peak immune responses after a single MVA-NP+M1 vaccination was significantly higher compared to ChAdOx1 NP+M1. In a mixed regression model, T-cell responses over 18months were significantly higher following the two dose vaccination regimen of MVA/ChAdOx1 NP+M1. INTERPRETATION: A two dose heterologous vaccination regimen of MVA/ChAdOx1 NP+M1 was safe and immunogenic in young and older adults, offering a promising vaccination strategy for inducing long-term broadly cross-reactive protection against influenza A. FUNDING SOURCE: Medical Research Council UK, NIHR BMRC Oxford.

A protein particle vaccine containing multiple malaria epitopes.

Ty virus-like particles consist of a single protein species that can be produced in yeast. Recombinant Ty-VLPs carrying a string of up to 15 defined cytotoxic T lymphocyte (CTL) epitopes from Plasmodium species prime protective CTL responses in mice following a single administration without adjuvant. Effective processing of epitopes from the string was demonstrated in vitro and in vivo and was not affected by flanking sequences.

Long term outcome of renal allografts in patients with immunoglobulin A nephropathy.

Recurrent glomerular disease is an important cause of late allograft loss in renal transplant recipients. Immunoglobulin A nephropathy (IgAN) is a leading cause of end-stage renal disease (ESRD) worldwide and its recurrence has been reported in allografts. The present study examined outcomes following renal transplantation (RTX) in 101 patients with ESRD due to biopsy-proven IgAN, in comparison to non-IgA patients, and evaluated the incidence of recurrence. The study population (mean age 34.8 +/- 7.7 years; males 62.2%; Chinese 88.3%) underwent RTX under CsA immunosuppression between November 1984 and December 2004; as two patients underwent retransplantation during the study period, 103 allografts (56.3% cadaveric) were included for retrospective analysis. At time of analysis on 1 January 2005, 78 (75.7%) renal allografts (IgAN RTX) were functioning, of which 51 (49.5%) had normal serum creatinine, 27 (26.2%) had chronic allograft dysfunction, while 25 had graft losses, either due to patient death with functioning grafts (5.8%) or withdrawal to dialysis (18.5%). Persistent microscopic haematuria, not attributable to other causes or proteinuria > 1 g/day occurred in 42.7% and 13.6% of allografts respectively. Of 29 allografts biopsied for evaluation of proteinuria and/or renal dysfunction post-RTX, 8 (27.6%) had IgAN (overall histological recurrence, 7.8%). Of these, three had graft loss due to recurrent IgAN, three had elevated serum creatinine, while two had normal serum creatinine. Overall five and ten year patient survivals for IgAN RTX were 95.3% and 82.2%, and five and ten year actuarial graft survivals were 82.3% and 67.8% respectively. Five and ten year patient and graft survivals for IgAN RTX were not significantly different from that for non-IgAN RTX. In summary, RTX patients with IgAN have a low incidence of documented histological recurrence and recurrence contributing to graft loss occurs in only 2.9%. These results suggest that RTX is an excellent modality of renal replacement therapy in this population.

3rd College of Physicians' lecture--translational research: From bench to bedside and from bedside to bench; incorporating a clinical research journey in IgA nephritis (1976 to 2006).

Translational research (TR) can be defined as research where a discovery made in the laboratory (bench) can be applied in the diagnosis, treatment or prevention of a disease. Examples of medical discoveries contributing to translational medicine (TM) include the isolation of insulin by Banting (Nobel Laureate, 1923), the discovery of penicillin by Alexander Fleming (Nobel Laureate, 1945) and recently the discovery of the role of bacterium Helicobacter pylori in the causation of gastritis and peptic ulcer by Marshall and Warren (Nobel Laureates, 2005). Clinical research (CR) would be a more appropriate term for the bulk of research work undertaken by doctors. CR embraces both clinical based and laboratory-based research. The terminology "bedside to bench" applies more to CR as opposed to "bench to bedside" in the case of TR. But regardless of who does it, as long as the discovery can be translated to the bedside and results in improvement in patient care it can be considered a contribution to TM. Our work spans a 30-year period, involving laboratory-based research, clinical trials and genomics of IgA nephritis (Nx). This is a series of work to elucidate the pathogensis and therapy of IgANx. Plasma beta-thromboglobulin (BTG) an in-vivo index of platelet aggregation and anti-thrombin III increase due to a constant thrombogenecity resulting from platelet degranulation formed the basis for anti-platelet and low-dose warfarin therapy. A study of the natural history of IgANx revealed 2 courses, a slowly progressive course with end-stage renal failure (ESRF) at 7.7 years and a more rapid course at 3.3 years. Triple therapy (cyclophosphamide, persantin and low-dose warfarin) delayed progression to ESRF by about 8 years and for some patients up to 20 years. Documentation of abnormal suppressor T cell function provided the basis for immune therapy. Four patterns of proteinuria were present in IgANx and it is the quality and not so much the quantity of proteinuria which determined the prognosis. Low molecular weight proteinuria was a bad prognostic marker. A controlled therapeutic trial using ACEI/ATRA showed that therapy decreases proteinuria, improves renal function and converts non-selective to selective proteinuria. Subsequent work confirmed that it was the ATRA, not the ACEI which contributed to improved renal function. Individual anti proteinuria response to ATRA varies depending on ACE gene polymorphism. We found that the II genotype of the ACE gene was renoprotective and patients with this genotype had significantly reduced incidence of ESRF compared to those with the DD genotype. Patients responsive to ATRA therapy can retard progression to ESRF by up to 32 years. Mild renal failure can be reversed with possible regression of glomerulosclerosis because of glomerular remodelling by ATRA.

Randomized trial of Alemtuzumab for prevention of graft rejection and preservation of renal function after kidney transplantation.

BACKGROUND: A randomized, multicenter, controlled trial was undertaken to evaluate the safety and efficacy of Alemtuzumab, a powerful lytic agent for both T and B lymphocytes, in the prophylaxis of rejection in renal transplantation (RTx). METHODS: Thirty patients were randomized to receive Alemtuzumab together with low-dose cyclosporine (CsA) monotherapy (CAMPATH, n = 20) or to full doses of CsA with azathioprine and corticosteroids (Standard, n = 10). CsA was administered at doses to achieve whole-blood trough CsA levels of 90 to 110 ng/mL and 180 to 225 ng/mL in CAMPATH and Standard groups, respectively. RESULTS: Per protocol, CsA trough levels were lower in patients assigned to CAMPATH post-RTx (median trough level of 119 vs. 166 ng/mL at 6 months, CAMPATH vs. Standard; 95% confidence interval, -92 to -34). At 6 months post-RTx, serum creatinine, graft and patient survivals, incidence of biopsy proven acute rejection (25% vs. 20%, CAMPATH vs. Standard), overall treatment failure, and severe and moderate infections were comparable. Whereas all patients receiving Standard therapy required maintenance corticosteroids at 6 months, of the 17 of 20 patients with functioning grafts in CAMPATH, 15 (88%, 95% confidence interval, 53%-97%) were steroid free. CONCLUSION: These results suggest that Alemtuzumab is an effective induction agent that permits low-dose steroid-free immunosuppression in RTx.

Methotrexate-induced cirrhosis requiring liver transplantation in three patients with psoriasis. A word of caution in light of the expanding use of this 'steroid-sparing' agent.

Methotrexate has been used for many years to treat refractory psoriasis. Three cases of methotrexate-induced cirrhosis requiring orthotopic liver transplantation are presented to emphasize the importance of strict adherence to published criteria for patient selection, monitoring of cumulative drug dosages, and the performance of serial liver biopsies. Each patient had been treated with long-term methotrexate therapy (cumulative doses far in excess of 1.5 g) without undergoing serial liver biopsies, contrary to well-established treatment guidelines. Caution must be exercised in using methotrexate as a steroid-sparing agent in the treatment of inflammatory diseases because of its potential to cause severe hepatotoxic effects with long-term usage and cumulative doses above 1.5 g. Patients easily become psychologically dependent on the drug, and physicians need to guard against the false sense of security engendered by normal results on liver function studies.

Comparative assessment of transmission-blocking vaccine candidates against Plasmodium falciparum.

Malaria transmission-blocking vaccines (TBVs) target the development of Plasmodium parasites within the mosquito, with the aim of preventing malaria transmission from one infected individual to another. Different vaccine platforms, mainly protein-in-adjuvant formulations delivering the leading candidate antigens, have been developed independently and have reported varied transmission-blocking activities (TBA). Here, recombinant chimpanzee adenovirus 63, ChAd63, and modified vaccinia virus Ankara, MVA, expressing AgAPN1, Pfs230-C, Pfs25, and Pfs48/45 were generated. Antibody responses primed individually against all antigens by ChAd63 immunization in BALB/c mice were boosted by the administration of MVA expressing the same antigen. These antibodies exhibited a hierarchy of inhibitory activity against the NF54 laboratory strain of P. falciparum in Anopheles stephensi mosquitoes using the standard membrane feeding assay (SMFA), with anti-Pfs230-C and anti-Pfs25 antibodies giving complete blockade. The observed rank order of inhibition was replicated against P. falciparum African field isolates in A. gambiae in direct membrane feeding assays (DMFA). TBA achieved was IgG concentration dependent. This study provides the first head-to-head comparative analysis of leading antigens using two different parasite sources in two different vector species, and can be used to guide selection of TBVs for future clinical development using the viral-vectored delivery platform.

Characterization of skin-infiltrating lymphocytes in patients with psoriasis.

In this study, skin-infiltrating cells in psoriasis patients were characterized in biopsies from both involved and uninvolved skin. Histologic examination of biopsies showed the presence of both CD4+ and CD8+ T cells and the lack of B lymphocytes. Skin biopsies were also placed in tissue culture medium supplemented with human serum, interleukin-2 (IL-2), and irradiated autologous blood lymphocytes. T lymphocytes grew from both plaques and univolved skin biopsies and consisted of a heterogeneous population of T-cell subsets. The immunophenotypic analysis of cultured cells was comparable to the histologic examination on frozen section, i.e., there was a greater number of CD4/CDw29+ cells than CD8+/CD45+ cells. Cultures were tested in the primed lymphocyte test (PLT) and cell-mediated lympholysis (CML) assays. All cultures tested demonstrated secondary proliferative but not cytolytic reactivity. The PLT results indicate that the cell cultures generated are autoreactive. This autoreactivity was found to be directed against non-human leukocyte antigens (HLA), i.e., minor HLA with some restriction to major HLA antigens.

Mannose binding protein deficiency is not associated with malaria, hepatitis B carriage nor tuberculosis in Africans.

We retrospectively studied MBP genotypes in patients with malaria, tuberculosis (TB), and persistent hepatitis B virus (HBV) carriage, in clinics and hospitals in The Gambia. Children under 10 years with cerebral malaria and/or severe malarial anaemia, were compared with children with symptomatic, mild malaria, and controls of the same age and ethnicity. Adult TB cases with smear-positive pulmonary TB were compared with healthy blood donors from the same ethnic groups. Malaria cases and controls were tested for hepatitis B core antibody (anti-HBc) and surface antigen (HBsAg). TB patients were tested for HIV antibodies. Genotyping used sequence-specific oligonucleotide analysis to identify MBP variant alleles. Overall, 46% (944/2041) of patients and controls were homozygous for the wild-type MBP allele, 45% (922/2041) were carriers of a single variant allele and 8.6% (175/2041) had two variant alleles. Neither homozygotes nor heterozygotes for MBP variants were at increased risk of clinical malaria, persistent HBV carriage or TB. The most common mutation in Africans, the codon 57 variant allele, was weakly associated with resistance to TB (221/794 in TB cases and 276/844 in controls, p = 0.037). MBP deficiency is not a significant risk factor for persistent HBV, severe malaria nor pulmonary TB in West Africa.

PIP: Low serum mannose-binding protein (MBP), a calcium-dependent serum lectin that acts as an opsonin to promote phagocytosis, has been characterized as the most common immune deficiency. It has been suggested that MBP acts as a binding protein for mycobacteria and other intracellular pathogens, enabling them to enter host macrophages. The present study investigated the association between variant MBP alleles and malaria, tuberculosis, and hepatitis B virus (HBV) in adults and children in The Gambia. Of the 2041 Gambians screened for MBP mutations, 944 (46%) were homozygous for the wild-type allele, 922 (45%) were carriers of a single variant allele, and 175 (8.6%) possessed 2 mutant alleles. Compared to healthy controls, neither homozygotes nor heterozygotes for MBP genotypes were at increased risk of severe malaria (n = 504), HBV carriage (n = 337), or tuberculosis (n = 397). Stratification of patients by ethnic group did not alter this lack of relationship. However, the most common mutation in Africans--the codon 57 variant allele--was weakly associated with resistance to tuberculosis in both cases and controls. Although MBP deficiency may predispose to recurrent infections, this study failed to provide evidence that such a deficiency is a major risk factor for infectious diseases.