Requirements for autoimmune responses to mouse gastric autoantigens

Autoimmune gastritis, in which the H+/K(+)-ATPase of parietal cells is the major antigen, is one of the most common autoimmune diseases. Here we examined if specific properties of the H+/K(+)-ATPase or parietal cells are involved in rendering them autoimmune targets. The model antigens beta-galactosidase and ovalbumin (OVA) were expressed in parietal cells of transgenic mice. On experimental induction of autoimmune gastritis by neonatal thymectomy, autoantibodies to beta-galactosidase developed in mice expressing beta-galactosidase in parietal cells, a response that was independent of either the response to the gastric H+/K(+)-ATPase or gastric inflammation. In contrast, mice that expressed OVA in parietal cells did not exhibit an antibody response to OVA after thymectomy. However, increasing the frequency of anti-OVA T lymphocytes in OVA-expressing mice resulted in autoantibodies to OVA and gastritis. These studies indicate that parietal cells can present a variety of antigens to the immune system. Factors such as the identity and expression level of the autoantigen and the frequency of autoreactive T cells play a role in determining the prevalence and outcome of the particular immune response. In addition, as not all mice of a particular genotype displayed autoimmunity, random events are involved in determining the target of autoimmune recognition.     

Binding of Streptococcus pyogenes to soluble and insoluble fibronectin.

The interaction of soluble and insoluble fibronectin with Streptococcus pyogenes was investigated. Soluble fibronectin bound to S. pyogenes in a dose-dependent and irreversible manner. Lipoteichoic acid competitively inhibited the binding of fibronectin to S. pyogenes but had little effect on the binding of fibronectin to staphylococci or pneumococci. The phase of growth of the streptococci had a slight effect on binding of fibronectin, with optimal binding occurring in the late log phase. S. pyogenes cells bound to fibronectin immobilized on microtiter plates in a dose-dependent and saturable manner. Both soluble fibronectin and lipoteichoic acid inhibited the binding of streptococci to immobilized fibronectin, suggesting that streptococci interact with soluble and insoluble fibronectin in a similar manner. Antibodies to fibronectin blocked the attachment of streptococci to immobilized fibronectin, whereas normal serum had no effect. Adherence of streptococci to buccal epithelial cells was inhibited by antibodies to fibronectin, but not by normal sera or by antibodies to buccal epithelial cells. The data suggest that lipoteichoic acid on the surface of S. pyogenes binds to fibronectin exposed on the host cell and that such binding mediates the attachment of streptococci to host cells.     

Human papillomavirus type 6 detected by the polymerase chain reaction in invasive sinonasal papillary squamous cell carcinoma.

Eight sinonasal carcinomas (one adenocarcinoma, two undifferentiated nasopharyngeal carcinomas, and five squamous cell carcinomas) were investigated for evidence of human papillomavirus (HPV) infection using in situ hybridization and the polymerase chain reaction for HPV types 6, 11, 16, 18, and 33. All eight cases were negative for HPV infection by in situ hybridization, while a single HPV-6-positive case was identified by the polymerase chain reaction. The HPV-positive case was an invasive papillary squamous cell carcinoma of the maxillary sinus. Although HPV-6 is usually associated with benign anogenital condylomata, it has been identified in malignant lesions of the upper respiratory tract. This may reflect exposure of the upper aerodigestive tract to additional carcinogens, such as smoke and alcohol, superimposed on the background proliferative stimulus of the HPV infection.     

Absence of HTLV I from New Zealand

Sera from 1,943 individuals from Auckland, New Zealand, were tested for the presence of serum antibodies to human T cell lymphotropic virus I (HTLV I), mainly with an enzyme-linked immunosorbent assay (ELISA) with cell extracts as target antigen. The individuals tested were blood donors and mostly Caucasian, but included indigenous Maoris and representatives of several groups of Pacific islanders now resident in New Zealand. Also included were 37 patients with various hematological malignancies, including seven with T cell leukemias. Although 1% of samples were positive by ELISA, none of these were confirmed as positives by Western blotting. On the basis of these results we consider that it is unlikely that HTLV I infection occurs in Auckland; however, we cannot exclude the possibility that pockets of virus infection may occur in other parts of New Zealand or the South Pacific.     

Multiple interactions between murine cytomegalovirus and lymphoid cells in vitro.

Spleen cultures from various strains of mice were infected in vitro with murine cytomegalovirus (MCMV). Infectious centres were established in a small proportion (not greater than 1%) of the cells. Virus could be rescued from these cells by co-cultivation with syngeneic or allogeneic fibroblasts, but the frequency of rescue could not be altered by incubation with cyclic nucleotide analogues, iododeoxyuridine, cortisol, or allogeneic spleen cells. In addition a smaller fraction of the cell population, possibly a sub-population of the infectious centres, replicated virus spontaneously. The presence of mitogens did not affect these interactions qualitatively or quantitatively. A third response to infection was an inhibition in DNA synthesis, which was suffered by unstimulated cultures and by cells transformed by concanavalin A and bacterial lipopolysaccharides, although overall cell viability was maintained. This response was also mediated by u.v.-inactivated virus.     

Characterization of lipoteichoic acid binding to polymorphonuclear leukocytes of human blood.

Human polymorphonuclear leukocytes (PMN) were shown to possess specific binding sites for lipoteichoic acid (LTA). LTA binding was reversible and time and temperature dependent. Scatchard plot analysis revealed an apparently single population of 6.6 X 10(6) LTA binding sites per PMN with a dissociation constant of 5.6 microM. Attachment of an avirulent, unencapsulated, M-negative strain of group A streptococci to PMN was inhibited by LTA, but not by other bacterial somatic antigens tested. Occupation of 30% of the LTA binding sites resulted in greater than 70% inhibition of streptococcal attachment to PMN. In contrast, LTA failed to block attachment of Escherichia coli or antibody-coated streptococci, indicating that binding sites for E. coli and the Fc portion of immunoglobulin G are distinct from those for LTA. Immunofluorescent studies demonstrated that LTA remained uniformly bound to PMN membranes for as long as 2 h at 37 degrees C. Cross-linking of PMN-bound LTA with anti-LTA resulted in rapid capping of LTA receptor sites. The results suggest that LTA is a monovalent ligand interacting with mobile receptors in the plasma membrane of PMN.     

Thymocyte expression of cathepsin L is essential for NKT cell development

CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell receptor V(alpha)14J(alpha)18 requires CD1d trafficking through endosomal compartments; however, the endosomal events remain undefined. We show that mice lacking the endosomal protease cathepsin L (catL) have greatly reduced numbers of V(alpha)14(+)NK1.1(+) T cells. In addition, catL expression in thymocytes is critical not only for selection of these cells in vivo but also for stimulation of V(alpha)14(+)NK1.1(+) T cells in vitro. CD1d cell-surface expression and intracellular localization appear normal in catL-deficient thymocytes, as does the lysosomal morphology; this implies a specific role for catL in regulating presentation of natural CD1d ligands mediating V(alpha)14(+)NK1.1(+) T cell selection. These data implicate lysosomal proteases as key regulators of not only classical major histocompatibility complex class II antigen presentation but also nonclassical CD1d presentation.     

Isolation and characterization of a large molecular-weight polypeptide of herpes simplex virus type 1

Infection of human embryonic lung cells at the nonpermissive temperature (39°) with tsB2, a DNA-negative mutant of herpes simplex virus type 1 (HSV-1) resulted in the accumulation of a large molecular-weight (175,000) virus-induced polypeptide detectable by SDS-polyacrylamide gel electrophoresis. This polypeptide (VP175) was detectable only in small amounts and was found mainly in the nuclear fraction of cells infected with tsB2 at the permissive temperature (34°) or with wild-type HSV-1 at both 34° and 39°. However at 39° VP175 accumulated to become the major component in both the cytoplasmic and nuclear fractions of tsB2-infected cells. Identical results were obtained with a second mutant (tsB21) in the same complementation group. Temperature-shift studies suggest that the events responsible for the accumulation of VP175 at 39° occur early in the replicative cycle. With the use of a combination of SDS-preparative and analytical disc gel electrophoresis, VP175 was isolated and rabbit antisera to this polypeptide were prepared. By immunofluorescence assay, anti-VP175 sera reacted only with the nucleus of wild-type HSV-1-infected cells, whereas tsB2-infected cells cultured at 39° showed both cytoplasmic and nuclear immunofluorescence. In addition, the anti-VP175 serum reacted preferentially with HSV-1 as compared with HSV-2-infected cells, suggesting a possible type specificity for the reagent.     

Efficacy and safety of fluticasone propionate 250 microg administered once daily in patients with persistent asthma treated with or without inhaled corticosteroids.

BACKGROUND: Studies have shown fluticasone propionate (FP) 100, 200, and 500 microg administered once daily to be effective in the treatment of asthma. The efficacy of a once daily regimen of FP 250 microg has not been evaluated previously. OBJECTIVE: We sought to evaluate the efficacy and safety of inhaled FP 250 microg administered once daily in patients currently receiving inhaled short-acting beta-agonists (SABA) alone or inhaled corticosteroids (ICS). METHODS: In two separate studies, 408 patients in the SABA study and 401 patients in the ICS study were randomly assigned to receive FP 250 microg or placebo for 12 weeks through the Diskus device (GlaxoSmithKline, Research Triangle Park, NC) each morning. RESULTS: At the study endpoint, SABA patients treated with FP and placebo had mean increases in forced expiratory volume in 1 second from baseline of 0.23 +/- 0.03 L and 0.10 +/- 0.03 L, respectively (P < 0.001). ICS patients treated with FP had a mean increase of 0.08 +/- 0.02 L compared with a decrease in forced expiratory volume in 1 second of -0.08 +/- 0.03 L with placebo (P < 0.001). Changes of similar magnitude in morning peak expiratory flow rates were seen with FP in both the SABA and ICS studies. Fewer FP-treated ICS study patients were withdrawn from the study as a result of predetermined asthma stability criteria and, therefore, those patients had a greater probability of remaining in the study than placebo-treated patients (P < 0.001). CONCLUSIONS: FP 250 microg, once daily, produced greater improvements in pulmonary function and asthma symptom control than placebo. This new treatment regimen provides clinicians with an additional therapeutic option for patients with asthma previously treated with either beta2-agonists alone or ICS.