Stimulation Of Specific Immune Responses Research Articles

Immunology of oral candidiasis.

A successful pathogen is one that is able to effectively survive and evade detection by the host immune defense. Oral candidiasis has adopted strategies, which evade host defense and eventually cause disease in at-risk patients. Host defense against infections with Candida spp. depends on rapid activation of an acute inflammatory response by innate immunity, followed by an incremental stimulation of specific immune responses mediated by T-cells (cellular immunity) or B-cells (humoral immunity). Understanding these complex pathways of immune evasion can potentially contribute to the development of novel therapeutic strategies against oral candidiasis.

Metastatic melanoma patients treated with dendritic cell vaccination, Interleukin-2 and metronomic cyclophosphamide: results from a phase II trial

Dendritic cells (DC) are the most potent antigen presenting cells and have proven effective in stimulation of specific immune responses in vivo. Competing immune inhibition could limit the clinical efficacy of DC vaccination. In this phase II trial, metronomic Cyclophosphamide and a Cox-2 inhibitor have been added to a DC vaccine with the intend to dampen immunosuppressive mechanisms. Twenty-eight patients with progressive metastatic melanoma were treated with autologous DCs pulsed with survivin, hTERT, and p53-derived peptides (HLA-A2(+)) or tumor lysate (HLA-A2(-)). Concomitantly the patients were treated with IL-2, Cyclophosphamide, and Celecoxib. The treatment was safe and tolerable. Sixteen patients (57%) achieved stable disease (SD) at 1st evaluation and 8 patients had prolonged SD (7-13.7months). The median OS was 9.4months. Patients with SD had an OS of 10.5months while patients with progressive disease (PD) had an OS of 6.0months (p=0.048) even though there were no differences in prognostic factors between the two groups. Despite the use of metronomic Cyclophosphamide, regulatory T cells did not decrease during treatment. Indirect IFN-γ ELISPOT assays showed a general increase in immune responses from baseline to the time of 4th vaccination. Induction of antigen-specific immune responses was seen in 9 out of 15 screened HLA-A2(+) patients. In conclusion, the number of patients obtaining SD more than doubled and 6-month survival significantly increased compared to a previous trial without Cyclophosphamide and Celecoxib. A general increase in immune responses against the tested peptides was observed.

The History and Mystery of VZV in Saliva

The History and Mystery of VZV in Saliva

Factors governing susceptibility to chemical allergy

Chemical allergy describes adverse health effects that result from the stimulation of specific immune responses by chemicals. Hypersensitivity reactions are the result of normally beneficial immune responses acting inappropriately against benign antigens, causing inflammatory reactions and tissue damage. The two most frequent manifestations of chemical-induced allergy are contact hypersensitivity and respiratory sensitization, both of which can have serious impact on quality of life, and represent a common occupational health problems. Chemical agents cause approximately 30% of cases of occupational asthma and roughly 90% of these cases involve immunological mechanisms (allergy). Over the past few decades industrialized countries have witnessed a significant increase (although the rate of increase has recently slowed) in the prevalence of atopic diseases including atopic rhinitis, bronchial asthma and urticaria. Many factors, both intrinsic and extrinsic, can contribute to the development of chemical allergy. In particular, the immune response can be affected by the genetic background, pathological conditions, hormonal and central nervous system status, etc. and by chemical related factors, e.g. dose level, frequency, route and duration of exposure, biotransformation, pharmacokinetics, chemical reactivity, etc. Furthermore, chemical pollution, indoor environment, diet, vaccination programs and the “hygiene hypothesis” have also been implicated in the increased prevalence of asthma and atopic diseases. Following the influence of condition of exposure, heritable and acquired factors, such as age, genetic background, gender etc. on chemical allergy is discussed.

Molecular characterization of woodchuck interleukin 15 (wIL-15) and detection of its expression in liver samples of woodchucks infected with woodchuck hepatitis virus (WHV)

Interleukin 15 (IL-15) is a member of the four-helix bundle cytokine family and has T cell growth factor activity. IL-15 plays a unique role in both innate and adaptive immune cell homeostasis, particularly for the development of NK cells and CD8 + memory cells. It may be useful for stimulation of specific immune responses in chronic viral infection such as hepatitis B virus infection. The woodchuck model is an informative animal model for studies on hepadnavirus infection and therapeutic interventions. Here, the complete coding sequence of woodchuck IL-15 (wIL-15) was cloned and sequenced. wIL-15 shows a high homology (>70%) to its counterparts of other mammalian species. His-tagged recombinant wIL-15 protein was expressed and purified and showed the ability to promote the proliferation of activated mouse splenocytes and woodchuck peripheral blood lymphocytes. Further, examination of mRNA amounts in liver samples of woodchucks by semi-quantitative RT-PCR showed a slightly increased expression of wIL-15 in woodchuck livers during chronic woodchuck hepatitis virus infection. This available information will provide a basis for further studies on the function of IL-15 in the context of acute and chronic hepadnavirus infection and its potential therapeutic use for chronic hepatitis B virus infection in the woodchuck model.

Virus evolution within patients increases pathogenicity

Viruses like the human immunodeficiency virus (HIV), the hepatitis B virus (HBV), the hepatitis C virus (HCV) and many others undergo numerous rounds of inaccurate reproduction within an infected host. The resulting viral quasispecies is heterogeneous and sensitive to any selection pressure. Here we extend earlier work by showing that for a wide class of models describing the interaction between the virus population and the immune system, virus evolution has a well-defined direction toward increased pathogenicity. In particular, we study virus-induced impairment of the immune response and certain cross-reactive stimulation of specific immune responses. For eight different mathematical models, we show that virus evolution reduces the equilibrium abundance of uninfected cells and increases the rate at which uninfected cells are infected. Thus, in general, virus evolution makes things worse. An idea for combating HIV infection, however, is constructing a virus mutant that could outcompete the existing infection without being pathogenic itself.

Immune responses: adverse versus non-adverse effects.

The adaptive immune system in vertebrates has evolved to provide host resistance to infectious microorganisms and malignant disease. Normal immune function and the induction of specific immune responses require the orchestrated interaction between cells and molecules both within and outside the lymphoid system. Immunotoxicology can be defined as the study of adverse health effects that may result from the interaction of xenobiotics with the immune system. In general terms such effects can take one of two forms. The first of these is immunotoxicity (or immunosuppression) where there is a perturbation of, or damage to, one or more components of the immune system resulting in impaired immune function and reduced host resistance. The design and interpretation of experimental immunotoxicity studies and the investigation of clinical immunosuppression require consideration of the relationship between changes in the structure and/or function of discrete components of the immune system and holistic changes in the susceptibility to infectious and malignant disease. The other main way in which chemicals may cause adverse health effects secondary to interaction with the immune system is through stimulation of specific immune responses that result in allergic disease. Allergy to chemicals and proteins can take many forms, including allergic contact dermatitis, allergic sensitization of the respiratory tract (associated with rhinitis and/or asthma), systemic allergic reactions (associated frequently with drug treatment), and gastrointestinal disease. Here there is a need to distinguish between immunogenic responses per se and those immune responses that are of sufficient vigor and of the quality necessary to provoke allergic sensitization. The purpose of this article is to explore the extent to which distinctions can be drawn between adverse and nonadverse effects in the context of immunotoxicity and allergy.

The role of immunity in susceptibility to respiratory infection in the aging lung

Respiratory tract infections, particularly pneumonia, are a leading cause of death in persons 65 years or older in both developed and developing countries. Because many attributes of immunity wane with advancing age, the elderly may be more susceptible to respiratory infections, even if they appear to be in good health. A decline in the ability of lymphoid tissues to mount an antigen-specific response (adaptive immunity) to specific microorganisms such as influenza virus or Streptococcus pneumoniae is thought to be an important factor in increasing susceptibility to respiratory tract infection with advancing age. However, abnormalities in innate immunity may also contribute to increased susceptibility to respiratory infections and have been poorly characterized in the elderly. Although changes in immune parameters such as T cell subsets and immunoglobulin concentrations have been observed in respiratory secretions from older healthy individuals compared to younger subjects, the significance of these changes for protective immunity in the lung is unknown. The incidence of pneumonia may be lessened by measures such as optimizing treatment of comorbid conditions, optimizing nutrition, and addressing swallowing disorders. The use of vaccines directed against the influenza virus and S. pneumoniae appears to have made an impact on the degree of morbidity and mortality, and perhaps, the incidence, of community-acquired pneumonia. However, better stimulation of specific immune responses with improved vaccines and more widespread use of these vaccines for protection of elderly individuals are needed.

Regulatory immunotoxicology--the scientist's point of view: an introduction.

Immunotoxicology describes adverse health effects that result from the interaction of xenobiotics with the immune system. In the context of consideration of some of the key regulatory issues, two main categories of adverse effects may be identified: immunotoxicity and allergy. The ability of chemicals to impair the functional integrity of one or more components of the immune system is defined as immunotoxicity. Here the concern is that compromised immune function will result in reduced host resistance and an increased susceptibility to infectious and malignant disease. Allergy describes the adverse effects that may be caused by the stimulation of specific immune responses; the most common manifestations of chemical-induced allergy being contact dermatitis and respiratory hypersensitivity associated with rhinitis and asthma.KeywordsContact DermatitisAllergic Contact DermatitisSpecific Immune ResponseRespiratory AllergyHazard IdentificationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.