Eosinophilic venulitis in the small intestines in a mouse model of late asthma

The allergen-unchallenged enteric lesions in late allergic asthma are largely unknown. To clarify this point, BALB/c mice were sensitized by ovalbumin (OVA)/aluminum adjuvant intraperitoneally two times (on days 0 and 10) and then challenged with OVA intranasally on day 14 (asthma group). Four days after the challenge, small intestinal lesions were examined. By this treatment, diarrhea was not observed in the asthma group. Compared to the controls with or without OVA sensitization and/or OVA challenge, the asthma group developed eosinophilic venulitis without an increase in mucosal mast cells in small intestines, whereas intestinal epithelial cells were relatively intact. A few numbers of interleukin (IL)-4(+) and IL-5(+) lymphoid cells were recognized in intestines in the asthma group, but not in the controls. Expression of vascular cell adhesion molecule-1 on venular endothelium and eotaxin-2(+) eosinophils, but not epithelial cells, in intestines were detected in the asthma group, but not in the controls. Total IgE, OVA-specific IgE and eotaxin, and IL-5, but not interferon-γ, were produced systemically in the asthma group compared to the controls. The present study suggests that eosinophilic venulitis without mast cells in the intestine may be induced by the systemic, but not by local, helper T 2-type responses. In addition, eosinophilic venulitis in small intestines may be subclinical enteric lesions.

Inactivated influenza virus, when presented on dendritic cells, elicits human CD8+ cytolytic T cell responses

Inactivated or subunit virus preparations have been excellent vaccines for inducing antibody responses. Generation of cytolytic T cell responses, however, is thought to require replicating virus, primarily to provide sufficiently large amounts of cytoplasmic proteins for processing and presentation on major histocompatibility complex class I molecules by antigen-presenting cells. Potent human CD8+ cytolytic T cell responses to live replicating influenza A virus are generated when dendritic cells are used as the antigen-presenting cells. Here, we demonstrate that dendritic cells pulsed with poorly replicating, heat- or ultraviolet-inactivated influenza virus, induce equally strong CD8+ cytolytic T lymphocyte responses. The cytotoxic T lymphocytes are generated in the apparent absence of CD4+ helper cells or exogenous cytokines. Active viral protein synthesis is not required to charge class I molecules on dendritic cells. When pulsed with inactivated virus, < 1% of dendritic cells express nonstructural protein 1, which is only synthesized in the infectious cycle. To be optimally effective, however, the inactivated virus must retain its fusogenic activity, and presumably access the cytoplasm of dendritic cells. The data indicate, therefore, that dendritic cells require only small amounts of viral protein to charge class I molecules, most likely via traditional class I processing pathways. These results reopen the potential use of inactivated virus preparations as immunogens for cytotoxic T lymphocyte responses.

Influenza virus-infected dendritic cells stimulate strong proliferative and cytolytic responses from human CD8+ T cells

Antigen-specific, CD8+, cytolytic T lymphocytes (CTLs) could potentially provide resistance to several infectious and malignant diseases. However, the cellular requirements for the generation of specific CTLs in human lymphocyte cultures are not well defined, and repetitive stimulation with antigen is often required. We find that strong CD8+ CTL responses to influenza virus can be generated from freshly isolated blood T cells, as long as dendritic cells are used as antigen presenting cells (APCs). Small numbers of dendritic cells (APC:T cell ratio of 1:50-1:100) induce these CTL responses from most donors in 7 d of culture, but monocytes are weak or inactive. Whereas both dendritic cells and monocytes are infected with influenza virus, the former serve as effective APCs for the induction of CD8+ T cells while the latter act as targets for the CTLs that are induced. The strong CD8+ response to influenza virus-infected dendritic cells is accompanied by extensive proliferation of the CD8+ T cells, but the response can develop in the apparent absence of CD4+ helpers or exogenous lymphokines. CD4+ influenza virus-specific CTLs can also be induced by dendritic cells, but the cultures initially must be depleted of CD8+ cells. These findings should make it possible to use dendritic cells to generate human, antigen-specific, CD8+ CTLs to other targets. The results illustrate the principle that efficient T cell-mediated responses develop in two stages: an afferent limb in which dendritic cells are specialized APCs and an efferent limb in which the primed T cells carry out an immune response to many types of presenting cells.

Correlation of functional recovery after a 6-hydroxydopamine lesion with survival of grafted fetal neurons and release of dopamine in the striatum of the rat

Female rats were lesioned with 6-hydroxydopamine in the left substantia nigra. At least two weeks later they were tested with amphetamine (5 mg/kg, s.c.) and apomorphine (0.25 mg/kg, s.c.). A cell suspension from the ventral mesencephalon of rat embryos was distributed in three sites in a triangular fashion in the center of the denervated striatum. The amphetamine test was then repeated every month for six months. The pattern of circling to amphetamine before the graft was strictly ipsiversive in all animals. From the first month we observed a progressive change and three patterns of rotation could be observed. In 21% of animals, the total number of ipsiversive turns in 90 min actually increased but during the first 20 min the animals turned contralaterally to the lesion (and to the graft). In 38% of animals, the total number of turns switched from ipsiversive to contraversive with the animals turning initially toward the intact side and during the second half of the test toward the lesion. Finally 41% of rats progressively switched to turning only toward the intact side. In all cases, maximal contraversive turning occurred during the initial 20 min. In these rats, tyrosine hydroxylase-positive cells were detected mainly in the dorsal striatum with a few in the central portion. Moreover there was a strong correlation between the number of surviving grafted neurons and the growth of their fiber into the host striatum and the extent of recovery.(ABSTRACT TRUNCATED AT 250 WORDS)