Mucosal FOXP3-expressing CD4+ CD25high regulatory T cells in Helicobacter pylori-infected patients

Helicobacter pylori chronically colonizes the stomach and duodenum and causes peptic ulcers or gastric adenocarcinoma in 10 to 20% of infected individuals. We hypothesize that the inability of patients to clear H. pylori infections is a consequence of active suppression of the immune response. Here we show that H. pylori-infected individuals have increased frequencies of CD4(+) CD25(high) T cells in both the stomach and duodenal mucosa compared to uninfected controls. These cells have the phenotype of regulatory T cells, as they express FOXP3, a key gene for the development and function of regulatory T cells, as well as high levels of the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) protein. In contrast, mucosal CD4(+) CD25(low) and CD4(+) CD25(-) cells express little FOXP3 mRNA and low levels of the CTLA-4 protein. Mucosal CD4(+) CD25(high) T cells are present in individuals with asymptomatic H. pylori infections as well as in duodenal ulcer patients. The frequencies of CD4(+) CD25(high) cells are also increased in the stomachs of H. pylori-infected patients with gastric adenocarcinoma, particularly in cancer-affected tissues. These findings suggest that regulatory T cells may suppress mucosal immune responses and thereby contribute to the persistence of H. pylori infections.     

Neural tissue xenografting

Neural transplantation may become an important treatment alternative for focal brain disorders. To date, the most successful grafts have been obtained in patients with Parkinson's disease. Completely normalized dopamine production and reduction of Parkinsonian symptoms have been demonstrated 10 years after grafting. However, the allogeneic donor tissue has to be obtained from induced abortions, and there are logistical difficulties, risks of infection, and ethical constraints limiting a wider clinical use. Xenografting is an alternative that could bridge these limitations if immunological rejection could be prevented. Pig embryonic neural tissue has been grafted to patients with Parkinson's disease, but no functional benefits have clinically been proven so far. The immune reactions to neural xenografts were incompletely characterized at the time of these early clinical trials, and it is likely that the treatments used were insufficient and that the grafts were rejected. In this article we will review new experiments addressing the immune responses against porcine neural tissue grafted to the adult brain, including the role of antibodies, complement, natural killer (NK) cells, lymphocytes, as well as the effects of immunosuppressive drugs and donor tissue modifications.     

Dispersion of horse allergen in the ambient air, detected with sandwich ELISA

BACKGROUND: The objective was to establish an ELISA to detect horse allergen in ambient air and settled dust. METHODS: Monoclonal antibodies (mAbs) were produced against extracts of horse antigen. Two mAbs were selected and used in a sandwich ELISA. By the aid of portable pumps, air samples were collected in one stable and in the ambient air surrounding this stable. Furthermore, settled dust was collected by wiping spots with pieces of fabric, at sites within 500 m of the stable. RESULTS: Extracts of horsehair could be extensively diluted and still be positive. Extracts of cat and dog allergen failed to be detected. Furthermore, the mAbs were shown to detect an IgE-binding component. This was demonstrated by an ELISA using mAbs as capture antibody and sera from horse-allergic subjects as secondary antibody with readout depending on anti-IgE antibody. The sera with the highest RAST class to horse were positive in this ELISA. Airborne levels of horse allergen were over 500-fold higher in the stable than just outside the stable and over 3000-fold higher than at a residential building located only 12 m from the stable. Similarly, an inverse correlation was found between the distance to the stable and levels of "outdoor settled" horse allergen (r=-0.9, P<0.001). CONCLUSION: We have developed a sensitive, horse-allergen-specific, mAb assay allowing detection of low levels of horse allergens. Raised levels of horse allergen were found outdoors only in the close vicinity of the stable.     

Immunizing with mouse trophoblast to obtain mouse-human cross-reacting antibodies against normal and neoplastic human trophoblast

Monoclonal antibodies raised against living, early invasive mouse trophoblast cells were screened on paraffin sections from first- and third-trimester placentas and from hydatidiform moles and choriocarcinoma. Several mouse-human cross-reacting antibodies were recognized, which implies that mouse trophoblast cells can be used as immunogen for producing antibodies against human trophoblast. Among the new antibodies obtained, some were selected for further study. That panel includes a trophoblast specific antibody with capacity to differ between invasive and noninvasive molar tissues, and two antibodies, which detect antigen epitopes in the normal, but not in the neoplastic trophoblast.     

Effects of acute and long-term atropine treatment on levels, release and response to VIP and PHI in the submandibular gland of cat and rat.

We have studied the effects of acute and long-term treatment of cats and rats with atropine on the levels, release and effects of two peptides, vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI), that probably co-exist with acetylcholine in the parasympathetic nerves supplying the submandibular gland. Atropine treatment (progressively increasing doses from 2 to 15 mg kg-1 injected s.c.) for 14 days did not alter the contents of VIP- or PHI-like immunoreactivity (-IR) in the cat submandibular gland or in three other tissues (nasal mucosa, trachea and tongue). Acute as well as long-term atropine treatment decreased the vasodilation following low-, but not high-, frequency parasympathetic nerve stimulation. During prolonged stimulation (60 min) there was a decreased vasodilatation response following both acute and long-term atropine treatment. The overflow of VIP-IR and PHI-IR following parasympathetic nerve stimulation was markedly increased by acute, but not by long-term atropine treatment. The VIP- or PHI-induced stimulation of cyclic AMP (cAMP) accumulation in the cat submandibular gland was not altered after long-term atropine treatment. Similarly, treatment of male Sprague-Dawley rats with atropine (20 mg kg-1) or imipramine (20 mg kg-1) for 14 days did not alter the sensitivity to VIP or to PHI of cAMP accumulation in the submandibular gland, nor was there any change in VIP-IR or PHI-IR content. In conclusion, although atropine treatment causes an acute increase in the overflow of VIP and PHI evoked by parasympathetic nerve stimulation, there is no depletion of peptide stores upon long-term treatment, nor is there any change in the effect of exogenous VIP and PHI on cAMP-accumulation.     

Intrasplenic immunization with minute amounts of antigen

There are two ways to raise antibodies to minute amounts of immunogen. The first is in-vitro immunization in which the immunogen is presented to a spleen cell culture and about a week later cell fusion for hybridoma production is attempted. The second, and the subject of this review, is intrasplenic immunization, in which the immunogen is deposited into the spleen tissue and the animal itself takes care of growing the spleen cells. Both of these techniques are appropriate when only small amounts of immunogen are available. Intrasplenic immunization, however, requires less laboratory work and there is a decreased risk of contamination, often a problem with hybridoma cultures. The experience of intrasplenic immunization shows that it is the method of choice for immunization with nanogram amounts of immunogen. A successful outcome, however, requires that the immunogen is immobilized on a carrier. This review by Ove Nilsson and Anders Larsson will focus on the various types of matrix which can be used as carriers and on the procedures for transferring these carriers into the spleen tissue.     

A highly discriminatory multi-typing scheme for Proteus mirabilis and Proteus vulgaris

Strains of Proteus mirabilis and P. vulgaris isolated in England, Scotland and Sweden were characterised by proticine production-proticine sensitivity (P-S) typing, O serotyping and Dienes typing methods. The determinants of O antigenicity were independent of those determining proticine production and proticine sensitivity. Because of this independence, the combination of P-S typing and O serotyping for the analysis of the 133 serotypable strains separated them into 81 distinct types whereas P-S typing and O serotyping methods alone separated them into only 56 and 19 types respectively. There was a relationship between the Dienes type and the P-S type; the determinants of Dienes compatibility were the proticine production-proticine sensitivity characters. The determinants of O antigenicity appeared to play no role in the Dienes reaction. Some strains that were indistinguishable by P-S typing and O serotyping methods were distinguished by Dienes typing.     

Activation of Lyt-2+ T cells by antibodies towards brain-associated antigens. I. Accessory cell requirement and role of Fc receptors in the induction of reactivity to interleukin 2

The present report describes a system where essentially all Lyt-2+ T cells are selectively activated by rabbit anti-mouse brain antibodies (RaMB) to interleukin 2 (IL 2) reactivity. High efficiency of RaMB-mediated induction was obtained by a 5 h incubation with antibodies at high cell density of Sephadex G-10-nonadherent spleen cells. No in situ production of IL 2 by RaMB-treated cells was detected, and proliferative responses were entirely dependent on exogeneous IL 2. RaMB-induced IL 2 reactivity was found to require accessory cells which are Fc receptor positive, and clearly distinct from those required to induce T cell proliferation in mixed lymphocyte cultures. We conclude that Lyt-2+ T cells are triggered to IL 2 reactivity by Fc receptor-mediated presentation of RaMB antibodies. The mechanism of induction by RaMB antibodies is discussed.