Co-stimulatory functions of antigen-presenting cells

Food Allergies: Immunosensors and Management

Food allergies (FA) are commonly depicted as immune responses. The mechanism of allergic reactions involves immunoglobulin E (IgE) and non-immunoglobulin E (non-IgE)-related responses caused by contact with specific foods. FAs can be fatal, have negative effects and have become the subject of fanaticism in recent years. In terms of food safety, allergic compounds have become a problem. The immune response to allergens is different to that from food intolerance, pharmacological reactions, and poisoning. The most important allergenic foods are soybeans, milk, eggs, groundnuts, shellfishes, tree nuts, cereals and fish, which together are known as the “Big Eight”. This review will introduce and discuss FAs in milk, peanuts, nuts, shellfishes, eggs and wheat and their detections and potential treatments will also be provided. We believe that this review may provide important information regarding food-induced allergies for children who have allergic reactions and help them avoid the allergenic food in the future.

Egg Allergy: Diagnosis and Immunotherapy

Hypersensitivity or an allergy to chicken egg proteins is a predominant symptomatic condition affecting 1 in 20 children in Australia; however, an effective form of therapy has not yet been found. This occurs as the immune system of the allergic individual overreacts when in contact with egg allergens (egg proteins), triggering a complex immune response. The subsequent instantaneous inflammatory immune response is characterized by the excessive production of immunoglobulin E (IgE) antibody against the allergen, T-cell mediators and inflammation. Current allergen-specific approaches to egg allergy diagnosis and treatment lack consistency and therefore pose safety concerns among anaphylactic patients. Immunotherapy has thus far been found to be the most efficient way to treat and relieve symptoms, this includes oral immunotherapy (OIT) and sublingual immunotherapy (SLIT). A major limitation in immunotherapy, however, is the difficulty in preparing effective and safe extracts from natural allergen sources. Advances in molecular techniques allow for the production of safe and standardized recombinant and hypoallergenic egg variants by targeting the IgE-binding epitopes responsible for clinical allergic symptoms. Site-directed mutagenesis can be performed to create such safe hypoallergens for their potential use in future methods of immunotherapy, providing a feasible standardized therapeutic approach to target egg allergies safely.

IL-2/anti-IL-2 mAb immunocomplexes: A renascence of IL-2 in cancer immunotherapy?

The in vivo biological activity of IL-2 can be dramatically increased by complexing with anti-IL-2 mAb. Moreover, IL-2/anti-IL-2 mAb immunocomplexes selectively stimulate different subsets of immune cells, depending on the clone of anti-IL-2 mAb that is used. Thus, IL-2/S4B6 mAb complexes strongly stimulate CD122^high populations, namely NK and memory CD8⁺ T cells. They also intermediately stimulate T_reg cells. Conversely, IL-2/JES6.1 mAb immunocomplexes have no stimulatory activity for CD122^high populations. However, they potently and highly selectively stimulate CD25⁺ cells (i.e., T_reg and activated T cells). IL-2/S4B6 mAb immunocomplexes have also been shown to possess antitumor activity in various mouse tumor models.

[Allergic rhinitis. Immunological and neurogenic mechanisms]

Allergic rhinitis is one of the most common diseases to affect humans. It is important to note that it is an immunological disease which is associated with significant changes in the mucous membrane of the respiratory tract. Clinical symptoms of allergic rhinitis include sneezing, rhinorrhea, nasal itching, and nasal congestion. The mechanism underlying the development of symptoms associated with allergic rhinitis are complex, including activation and infiltration of inflammatory cells, edema, increased and altered gland activity, nerve terminal activation, triggering of neurogenic inflammation and morphologically detectable remodelling processes in the mucous membrane. Finally, a systematic activation of immune processes also takes place. Thus, allergic rhinitis is clearly a serious disease requiring prompt and effective treatment; moreover, it has been unjustly trivialized to date, not least because of its high incidence.

Early detection of allergic diseases in otorhinolaryngology

Asthmatic diseases have been reported since the ancient world. Hay fever for instance, was described for the first time in the late 18(th) century, and the term "allergy" was introduced about 100 years ago. Today the incidence of allergies is rising; almost one third of the Western population suffers from its side effects. Allergies are some of the most chronic medical complaints, which results in high health expenditures. Therefore, they have a large health and political relevance.Caused by genetic and environmental factors, the group of IgE mediated allergies is large. It consists of e.g. atopic dermatitis, allergic asthma or allergic rhinitis. This paper aims to emphasize the ways of early diagnosis of allergic rhinitis (AR) as AR represents the most important representative of allergic diseases in ENT.

Prolongation of skin allograft survival is associated with reduced Th1 cytokine responses in the WKY-->F344 rat model

BACKGROUND

We have reported previously that F344 rats develop a spontaneous tolerance to WKY lung allografts and show long-term retention of donor-specific skin grafts placed 35 days after lung transplantation. In this study, we investigated the immunologic mechanisms that may be responsible for the prolonged skin graft survival in animals tolerized with lung allografts.

METHODS

In the rejection group, WKY skin grafts were placed on normal F344 rats, whereas, in the tolerance group, the skin grafts were placed on F344 rats that had received a WKY lung transplant 35 days before skin grafting. Th1 (interleukin [IL]-2 and interferon-gamma [IFN-gamma]) and Th2 (IL-4 and IL-10) cytokine as well as transforming growth factor-beta1 mRNA expression in skin grafts and in draining lymph nodes were determined by reverse transcription-polymerase chain reaction. Macrophage and lymphocyte infiltration in skin grafts and the number of Langerhans cells in epidermal sheets of the grafts were examined by immunohistochemistry.

RESULTS

IL-2 and IFN-gamma mRNA expression was significantly decreased in both the skin grafts and the draining lymph nodes of the tolerance group, compared to the rejection group, whereas IL-10 and transforming growth factor-beta1 mRNA expression was similar in both groups and IL-4 mRNA was rarely detected. Decreased and delayed CD8+, macrophage, and natural killer cell infiltration in the skin grafts from the tolerance group was also detected. Similar reduction in the number of Langerhans cells in the epidermis of the grafts from both groups was seen on day 1 after skin grafting, and thereafter the number remained stable in both groups.

CONCLUSIONS

Reduced expression of Th1 cytokines and decreased infiltration of CD8+ cells, macrophages, and natural killer cells in the skin grafts may be responsible for prolongation of skin graft survival in the tolerance group.

Immunohistochemical localization of CD1a-positive putative dendritic cells in human breast tumours

The presence of a high number of infiltrating CD1a+ cells in malignant neoplasms has been reported to be associated with an improved prognosis, reduced tumour recurrence and fewer metastases. This study identified a population of CD1a+ cells within the lymphoid cell infiltrate in human ductal breast carcinoma (n = 52), which was significantly different from normal breast tissue, in which only two out of nine cases expressed CD1a+ cells (P = 0.0192). In the majority of cases, the infiltrate was low compared with the number of macrophages and T cells present (results not shown). There was no correlation between the number of CD1a+ cells and tumour grade, with all tumour grades expressing similar numbers of infiltrating CD1a+ cells. There was clear evidence, however, that the CD1a+ cells were closely associated with tumour cells. It is likely that CD1a+ cells have a role in antigen capture and presentation in human tumours, and this study documents the density of CD1a+ cells in a large sample of all histological grades of human breast carcinomas.

The potential role of dendritic cells in immune-mediated inflammatory diseases in the central nervous system

Dendritic cells of the rat were studied immunohistochemically with MRC OX62 monoclonal antibody and using electron microscopy. In normal CNS, a small number of OX62+ cells was detected in the choroid plexus and meninges. These cells were absent from other CNS and peripheral nervous system sites studied. Dendritic cells were also studied in two models of immune-mediated inflammatory conditions in the CNS. These were: acute experimental allergic encephalomyelitis and aberrant delayed-type hypersensitivity lesions induced as a response to heat-killed bacillus Calmette-Guérin sequestrated behind the blood-brain barrier. In addition, a group of animals with a delayed-type hypersensitivity response was treated with dexamethasone to assess the effect of steroid treatment on T-cells and OX62+ cells in CNS lesions. Dendritic cells were present in many but not all lesions in acute experimental allergic encephalomyelitis and their numbers were small. In experimental allergic encephalomyelitis lesions, dendritic cells were found predominantly in perivascular cuffs, where they constituted approximately 2% of the total number of major histocompatibility complex class II+ cells. Some of these cells were also detected in the CNS parenchyma, close to the perivascular cuff. In contrast, dendritic cells were present in all delayed-type hypersensitivity lesions studied. Their number in delayed-type hypersensitivity lesions was significantly higher than in experimental allergic encephalomyelitis lesions. Numerous OX62+ cells were found, even in three-month-old lesions. Electron microscopy studies revealed that these cells were often in close contact with lymphocytes. There was no significant change in the density of OX62+ cells, IL2R+ cells and OX19+ T-cells in delayed-type hypersensitivity lesions after seven-day treatment with dexamethasone, although there was a considerable reduction in the number of CD45RA+ T-cells. The high numbers of dendritic cells found in the delayed-type hypersensitivity lesions may be important in contributing to the chronicity of the response. They may also initiate autoimmune responses to CNS antigens uncovered during bystander tissue damage which occurs as a consequence of aberrant delayed-type hypersensitivity responses.

Role of B7 signaling in the differentiation of naive CD4+ T cells to effector interleukin-4-producing T helper cells

Signaling through the T cell receptor must be accompanied by costimulatory signals for the differentiation of naive T cells to cytokine-producing effector T helper cells. The costimulatory signal through CD28 is required for T cell activation resulting in increased interleukin (IL)-2 production in vitro, but its role in the production of IL-4 and in the in vivo response is still unclear. We have examined the effects of blocking CTLA-4 (the CD28 homologue) ligand interactions on the in vivo development of IL-4-producing T helper effector cells during a primary mucosal immune response to the nematode parasite Heligmosomoides polygyrus and during a primary systemic immune response to immunogenic anti-IgD antibodies. Our results demonstrate that CD28 and/or CTLA-4 signaling is required for T cell priming leading to IL-4 cytokine production, B cell activation, and IgE secretion during both immune responses, suggesting that other signaling molecules do not substitute for these molecules in either of these two different immune responses. Furthermore, the CD28 ligands, B7-1 and B7-2, can substitute for each other in providing the required T cell costimulatory ligand interactions during the primary immune response to H. polygyrus. In contrast, memory T cells during the challenge immune response do not require CD28/CTLA-4 ligand interactions for IL-4 production and T helper effector function.

Cutaneous defenses against dermatophytes and yeasts

Predispositions to the superficial mycoses include warmth and moisture, natural or iatrogenic immunosuppression, and perhaps some degree of inherited susceptibility. Some of these infections elicit a greater inflammatory response than others, and the noninflammatory ones are generally more chronic. The immune system is involved in the defense against these infections, and cell-mediated immunity appears to be particularly important. The mechanisms involved in generating immunologic reactions in the skin are complex, with epidermal Langerhans cells, other dendritic cells, lymphocytes, microvascular endothelial cells, and the keratinocytes themselves all participating in one way or another. A variety of defects in the immunologic response to the superficial mycoses have been described. In some cases the defect may be preexistent, whereas in others the infection itself may interfere with protective cell-mediated immune responses against the organisms. A number of different mechanisms may underlie these immunologic defects and lead to the development of chronic superficial fungal infection in individual patients. Although the immunologic defects appear to be involved in the chronicity of certain types of cutaneous fungal infections, treatment of these defects remains experimental at the present time.