Biology of NKT Cells - Research Paper Example

? Review of the Biology of NKT Cells Review of the Biology of NKT Cells Natural Killer T cells (NKT) form a unique lineage oflymphocytes that exhibit unique characteristics depending on the associated T-cell repertoires. Immunologists have described three types of NKT cells in their efforts to analyze the roles played by these cells in promoting immune system functions. Thefunction of these NKT cells is closely linked to the development of atopic diseases such as asthma and dermatitis. With the alarming increase of asthma and other allergic diseases in the developing world, there is need for developing effective strategies to combat the high prevalence. Immunologists have been striving to unearth the connection between NKT cells and the inflammatory characteristics of asthma, in a bid to design new intervention strategies. This paper will review the biology of Natural Killer T cells and the prevention strategies of asthma and allergic diseases. Biology of NKT Cells Natural Killer T cells form a subset of lymphocytes as scientists have described. Depending on the T-cell receptor repertoires, NKT cells fall into three categories. The first type of NKT cells is the classical NKT cells that exhibit conserved T-cell receptors (Akbariet al 2006). Immunologists have been described type 1 NKT cells in mice and humans, with those in humans named invariant NKT cells. Type 2 is also available in both mice and humans but have a diverse range of T-cell receptors. However, type 2 faces a restriction from CD1d. The third type forms the independent category of NKT cells characterized as expressing either Ly49 or NK1.1 (CD161 in humans). Moreover, it proved quite difficult to isolate this type of NKT cells. Immunologists have succeeded in isolating type 1 and associating it with the development of asthma. NKT cells present numerous similarities to Th2 Cells, which trigger the processes that cause the development of asthma. Both Th2 and NKT have the ability to produce cytokines namely interleukin IL-4 and IL-13. Th2 also exhibit T-cell receptors, similar to the NKT cells as described above. Moreover, both types of cells also exhibit the expression of CD4 marker, and often gain access to the pulmonary environment where they trigger inflammation of the airway. However, the two types of cells exhibit different activation processes (Wohlleben&Erb, 2006). Processes Leading to the Development of Asthma and related Atopic Diseases Experts seeking to understand the immunologic processes that lead to the development of asthma, have described the process in detail. Asthma results from the Th2 responses taking place in the lungs. The production of Th2 responses result from the action of allergen specific CD4+. The basis of asthma development is that there must be activation of transcription factors from the downstream factors resulting to the production of Th2 effector cells. The effect of these processes is the production of cytokines such as interleukins IL-4, IL-5, IL-9, and IL-13. Moreover, these processes trigger the recruitment of eosinophils and allergen specific immunoglobulin E by beta cells (Mallevaey et al, 2006). Granulation of eosinophils and mast cells occurs with as they indulge in a cross-linking with immunoglobulin E (igE). This causes the production of mucous and airway hyper-reactivity and a chronic inflammation of the airway. These are the central attributes of asthma.Processes that trigger Th2 responses often lead to airway hyper-reactivity and inflammation. Immunologists have highlighted that Th1 responses do not trigger this hyper-reactivity and inflammation defining asthma and other atopic diseases. There is evidence suggesting that children contacting bacterial infections that trigger Th1 responses in their earlier years have a less likelihood of developing asthma. NKT Cells and Asthma There is evidence that NKT cells have the potential to trigger Th2 responses that often lead to development of asthma and other atopic diseases. This is because of their ability to recognize glycolipid antigens despite the presentation of such antigens by the non-polymorphic MHC class1 protein called CD1d [19–21]. The fact that the expression of these proteins is rampant in epithelial cells especially in the airway explains the linkage of these invariant NKT cells with the development of asthma. On the other hand, type 2 of the NKT cells have the ability to recognize the glycolipid antigens presented by the MHC class 2 molecules. Invariant NKT cells often cause an increased production of cytokines within a few minutes of their activation. This implies that these cells have the potential of demonstrating an immunity that resembles innate immunity. Moreover, their ability to produce such cytokines explains why they have the ability to exert a form of regulation in the development of anti-transplant immune responses, antimicrobial, antitumor, and autoimmune diseases. The effect of such regulation has either causative or preventive effects (Wanget al, 2006). Cytokins IL-4 and IL-13 are the most critical in asthma development. There is evidence that both invariant NKT cells and Th2 cells play a critical role in the development of asthma. Research has indicated that airway hyper-reactivity only occurs in the presence of invariant NKT cells. Although invariant NKT cells are highly significant in asthma development, it has become evident that they cannot cause asthma without the presence of Th2 cells. Th2 cells have the unique ability to recognize environmental allergens that trigger asthma development. It is evident that the coupled effect of Th2 and invariant NKT cells cause asthma. Recent Research in this Area One of the recent researches has sought to determine the role of invariant NKT cells in the development of asthma and other atopic diseases. This research has adopted the approach of observing animal models, specifically mice in the research carried by Umetsu and colleagues (Umetsu, Meyer, &DeKruyff, 2007. That research revealed that invariant NKT cells play a critical role in the development of asthma. This is a significant research because understanding the immunological processes triggered by invariant NKT cells is the basis in developing any intervention strategies. An additional research has sought to establish whether it is possible to regulate asthma development (Umetsu&DeKruyff, 2006). The approach of using animal models and monitoring of individuals’ immunological processes have served to yield intriguing findings. In the last five years, immunologists have also focused on the development and testing of the efficiency of vaccines in animal models. There is a cloud of evidence suggesting that vaccine intervention can prevent asthma. Other researches have highlighted that triggering Th1 responses in animal models reduces chances of Th2 responses. All these researches target to design effective strategies against asthma. Evidently, the findings from these researches can serve to influence health care decisions concerning asthma cases. Conclusion Asthma and other atopic diseases have increased in the recent past causing concern, and prompting research on the factors that trigger the development of such allergic diseases. It is evident from recent research that NKT cells play a critical role in triggering airway hyper-reactivity and inflammation, the attributes that characterize asthma. With the emerging hope of combating asthma development with vaccines or the induction of Th1 responses, the globe can look forward to effective regulation of asthma and allergy. 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