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Biomedical subjects

E Heinen

Publications and source records attributed to E Heinen.

At least 19 recordsLinked to original sources
PubMed1997

Human follicular dendritic cells in vitro and follicular dendritic-cell-like cells.

Human follicular dendritic cell (FDC)-like cells (FLC) have been utilized for the in vitro analysis of germinal center reactions. However, there is no consensus whether FLC represent FDC in vitro. The purpose of the present study has therefore been to determine distinguishing features of FDC and FLC in vitro. The expression of CD40, CD54, CD49d, cytokine (gamma-IFN and IL-4)-dependent MHC-class II, and CD106 was observed to be specific for the determination of FDC in long-term culture. The cytokine-dependent emperipolesis of germinal center B cells was establised as another discriminating property for FDC in vitro. In 2 out of 72 long-term cultures of FDC, we encountered dividing cells among the non-dividing population of FDC. The dividing cells expressed accessory molecules similar to those of FDC but showed emperipolesis only for the initial few days of their growth. FDC did not enhance the CD40-dependent proliferation of germinal center B cells; in contrast, FLC augumented it. Both types of cells produced a significant amount of cytokine-dependent IL-6. Further studies are needed to determine whether FLC originate from FDC in vitro.

Cell Adhesion↗
PubMed1996

Regulation of dendritic cell numbers and maturation by lipopolysaccharide in vivo.

Dendritic cells (DC) are described as "nature's adjuvant," since they have the capacity to sensitize T cells in vivo upon first encounter with the antigen. The potent accessory properties of DC appear to develop sequentially. In particular, the ability to process antigens and to sensitize native T cells develops in sequence, a process termed "maturation" that is well described in vitro. Here, we obtain evidence for maturation in vivo in response to the bacterial product lipopolysaccharide (LPS). Before LPS treatment, many DC are found at the margin between the red and white pulp. These cells lack the M342 and DEC-205 markers, but process soluble proteins effectively. 6 h after LPS, DC with the M342 and DEC-205 markers are found in increased numbers in the T cell areas. These cells have a reduced capacity to process proteins, but show increases in the B7 costimulator and T cell stimulatory capacity. 48 h after LPS, the number of DC in the spleen is reduced markedly. We interpret these findings to mean that LPS can cause DC in the marginal zone to mature and to migrate into and then out of the T cell areas.

Animals↗
PubMed1996

A gE deleted infectious bovine rhinotracheitis marker vaccine for use in improved bovine herpesvirus 1 control programs.

Based on a glycoprotein E (gE) deleted bovine herpesvirus 1 (BHV1) strain (Kaashoek et al., 1994) a killed virus as well as a modified live virus marker vaccine have been developed that allow differentiation between immunized and BHV1 infected cattle. Safety and efficacy of both vaccines were tested extensively following the current European Union (EU) requirements for the development of bovine vaccines. The minimum vaccine dose, vaccination regimen, route of administration and duration of immunity were evaluated for both vaccines in comprehensive vaccination/challenge trials in cattle. The most potent adjuvant formulation for the killed virus vaccine was also selected by experimental challenge infections. For the modified live virus marker vaccine it could be demonstrated that maternally derived BHV1 specific antibodies did not interfere with vaccination. Safety could be demonstrated for both the killed virus and the modified live virus vaccine in all target animal categories including veal calves, beef cattle, bulls, heifers and dairy cattle, including pregnant animals.

Animals↗
PubMed1996

The influence of follicular dendritic cells on B-cell proliferation depends on the activation of B cells and the mitogen used.

Follicular dendritic cells (FDC) are unique non-lymphoid cells found only in lymph follicles. They play a part in the survival, proliferation and differentiation of B cells. To analyse the influence of FDC on B-lymphocyte proliferation, we isolated them from human tonsils on albumin gradients and treated them with mitomycin C to prevent the multiplication of lymphoid cells harboured in their cytoplasmic evaginations. FDC cultured for 12-16 h remained attached to the substrate; non-adherent cells were carefully eliminated by washing. Purified B cells cultured alone or with contaminant-cleared FDC were maintained for 2 days in the presence or absence of various stimulants, after which tritiated thymidine uptake by these cells was measured. In the absence of activators, FDC did not induce B-cell multiplication. B cells cultured in the presence of FDC exhibited increased 3H-TdR uptake when activated with anti-CD40 MoAb, anti-immunoglobulin MoAb or transferrin, but not when stimulated with Staphylococcus aureus strain Cowan I (SAC) at a given concentration. In the latter case, B-cell proliferation clearly decreased. In control cocultures where mitomycin-C-treated non-adherent cells were used instead of FDC in the presence of the different stimulants, no increase in B-cell proliferation was observed. The results suggest that, inside the germinal centres, FDC modulation of B-cell proliferation depends on the activation state of the B cells and on the stimulant encountered.

Antibiotics, Antineoplastic↗
PubMed1996

Intestinal Chlamydia in finishing pigs.

Gut and blood samples from 119 finishing pigs derived from 11 farms were collected during routine slaughter at an abattoir. Sections of formalin-fixed, paraffin-embedded tissues were labeled immunohistochemically using genus-specific, mouse monoclonal antibody against chlamydial lipopolysaccharide; goat polyclonal antiserum against the major outer membrane protein of Chlamydia trachomatis; and mouse monoclonal antibody against the ovine abortion subtype of C. psittaci. Gut samples from 33 of 111 (29.7%) individual pigs stained positive with the genus-specific monoclonal antibody, and of these 30 of 32 (93.7%) also reacted with the C. trachomatis-specific antiserum. Labeled inclusions were restricted to mature enterocytes of the large intestine in 33 of 111 cases. Infection of small intestinal enterocytes was noted in only one of 82 ileal samples. The blood samples were tested for antichlamydial antibodies by enzyme-linked immunosorbent assay (ELISA) and complement fixation test (CFT). With ELISA, 95 of the 115 sera tested (82.6%) yielded positive antichlamydial reactions. With CFT, 34 of the 119 sera tested (28.6%) were unequivocally positive (> or = 1:10, 100% binding), and 10 (7.6%) yielded doubtful positive reactions (1:10, 50-75% binding). Positive ELISA and CFT titers showed poor agreement (kappa = 0.112), whereas the agreement between positive findings by immunohistochemical labeling and CFT was fair (kappa = 0.205).

Animals↗
PubMed1996

In vitro and in vivo stimulation of the murine immune system by AGM-1470, a potent angiogenesis inhibitor.

AGM-1470, a potent angiogenesis inhibitor, is already engaged in phase I clinical trials because of its effectiveness to restrain tumor growth and its lack of major side effects. Recently, we showed that AGM-1470 stimulates in vitro human B lymphocyte proliferation through T lymphocytes. These data prompted us to explore the in vivo effects of AGM-1470 on the immune system in a mouse model. In this study, we showed that AGM-1470, in synergy with phytohemagglutinin, stimulates the proliferation of murine lymphocytes isolated from lymph nodes. This effect was similar to the one observed with human lymphocytes. When injected subcutaneously or intraperitoneally into mice at pharmacological doses, AGM-1470 induced a significant increase of axillary and mesenteric lymph nodes, respectively. Histological and morphological analyses showed that this phenomenon is mostly due to a hyperplasia of the germinal centers. On average, the area of the germinal center of lymph nodes from AGM-1470-treated mice were three times larger than in lymph nodes from control mice. Interestingly, no effect was observed when AGM-1470 was injected subcutaneously into T-deficient nude mice. Our data demonstrate that AGM-1470 stimulates B cell proliferation in vivo as suggested by the in vitro experiments. This effect should be taken into account in the follow-up of patients treated with this molecule and calls for additional studies to determine the biological consequences of such a stimulation on the host immune system.

Animals↗
PubMed1995

Human germinal center CD4+CD57+ T cells act differently on B cells than do classical T-helper cells.

We have isolated two subtypes of helper T cells from human tonsils: CD4+CD57+ cells, mostly located in the germinal center (GC), and CD4+CD57- cells, distributed through the interfollicular areas but also present in the GC. In a functional study, we have compared the capacities of these T-cell subtypes to stimulate B cells in cocultures. In order to block T-cell proliferation while maintaining their activation level, we pretreated isolated T cells with mitomycin C prior to culture in the presence of B cells and added polyclonal activators such as PHA and Con A, combined or not with IL-2. Contrary to CD4+ CD57- cells, CD4+CD57+ cells did not markedly enhance B-cell proliferation. Even when sIgD.B cells typical of germinal center cells were tested, the CD4+CD57+ cells had no significant effect. This is in accordance with the location of these cells: They mainly occupy the light zones of the GC where few B cells divide. Even when added to preactivated, actively proliferating cells, CD4+CD57 cells failed to modulate B-cell multiplication. On the supernatants of B-cell-T-cell cocultures, we examined by the ELISA technique the effect of T cells on Ig synthesis. Contrary to CD57+ T cells, whose effect was strong, CD57- T cells weakly stimulated Ig synthesis. More IgM than IgG was generally found. Because CD57 antigen is a typical marker of natural killer cells, we tested the cytolytic activity of tonsillar CD4+CD57+ cells on K562 target cells. Unlike NK cells, neither CD4+CD57+ nor CD4+CD57- cells exhibit any cytotoxicity. Thus, germinal center CD4+CD57+ cells are not cytolytic and do not strongly stimulate either B-cell proliferation or Ig secretion. CD4+CD57- cells, however, enhance B-cell proliferation and differentiation, thus acting like the classical helper cells of the T-dependent areas.

B-Lymphocytes↗
PubMed1995

Safety aspects in the development of an infectious bovine rhinotracheitis marker vaccine.

Clinical trials in cattle demonstrated that the IBR marker modified live vaccine based on the gE-deleted IBR strain Difivac is immunogenic and safe for bovines of all ages. Potential effects of the vaccine virus have also been tested in swine and sheep and proved safe for these species as well. For evaluation of other environmental aspects, the spread of the vaccine virus after immunisation was investigated. The data indicated that the vaccine virus may be shed by immunised animals but that it has a limited ability to pass from animal to animal. It was also demonstrated that the attenuated Difivac strain does not revert to virulence during calf passage. Preliminary results indicated that the gE-deleted vaccine virus of the IBR marker vaccine cannot be reactivated after dexamethasone treatment, an important advantage for a vaccine strain. Furthermore, immunisation with the Difivac strain reduced the ability of a superinfecting challenge virus to become latent or to be reactivated.

Animals↗
PubMed1995

[Immunohistochemical determination of Chlamydia psittaci/pecorum and C.trachomatis in the piglet gut].

The jejunum, ileum, caecum and colon of 200 piglets were investigated immunohistochemically for the presence of Chlamydia psittaci and C. trachomatis using a vitelline IgY. Positive samples were later labelled using a commercial C. trachomatis polyclonal antiserum. Chlamydia were present in 33 (16.4%) of the animals, and 30 out of 33 were labelled by C. trachomatis polyclonal antiserum. Inclusions occurred predominantly (67%) in the large intestine. The serological results (CFT, ELISA) did not correlate well with immunohistochemical labelling in the gut. The incidence of Chlamydia rose from 6.9% in animals up to 4 weeks, to 41.8% in those over 4 weeks of age. A correlation between chlamydia and enteric disease was not obvious. Besides chlamydia, most of the diseased animals harboured other additional agents. In conclusion, intestinal chlamydiae in piglets, predominantly C. trachomatis, exist in Switzerland, although their pathogenic potential seems to be low.

Animals↗
PubMed1995

[Follicular dendritic cells: phenotype, origin and functions].

Follicular dendritic cells (FDC) are only located in lymph node follicles and particularly developed in the light zones of the germinal centers. FDC differ on important points from the classical dendritic cells presenting antigens to T cells. They are long-lived and derived from local mesenchymal cells. Their complex cytoplasmic extensions, covered with dendrites, are intermingled in a network which surrounds germinal B and T cells. On their surface, receptors fix immune complexes without endocytosis and adhesion molecules ensure close contacts to the lymphoid cells. FDC influence the migration, activation, proliferation, survival and differentiation of B cells into memory cells and probably act also on the germinal center T cells.

Acquired Immunodeficiency Syndrome↗
PubMed1994

AGM-1470, a potent angiogenesis inhibitor, prevents the entry of normal but not transformed endothelial cells into the G1 phase of the cell cycle.

AGM-1470 is a potent angiogenesis inhibitor that is very effective in inhibiting endothelial cell proliferation in both in vitro and in vivo models and that prevents tumor growth in vivo. Although this molecule appears to be a most promising anticancer drug, its mechanism of action has not yet been elucidated. In this study, we examined the effects of AGM-1470 on the cell cycle of normal and transformed endothelial cells. We showed that AGM-1470, at picomolar concentrations, specifically inhibits the proliferation of both bovine aortic endothelial cells and human umbilical vein endothelial cells. AGM-1470 was ineffective in significantly inhibiting the proliferation of Ea.hy926 cells, a hybrid cell line obtained by the fusion of human umbilical vein endothelial cells with a human carcinoma cell line, or cEnd.1 cells, a polyoma middle T oncogene-transformed endothelioma cell line derived from mouse embryo. Using a double labeling technique with anti-Ki67 antibodies and propidium iodide, we demonstrated, with flow cytometry analysis, that AGM-1470 specifically prevents the entry of endothelial cells into the G1 phase of the cell cycle. We also showed that AGM-1470 was ineffective in inhibiting endothelial cell migration toward laminin or capillary-like tube formation inside a type I collagen matrix induced by phorbol esters. Our data strongly suggest that AGM-1470 is a molecule that specifically inhibits a cell cycle control pathway active in normal cells but which could be bypassed or altered in transformed cells.

Animals↗