The immune system is composed of two parts firstly the innate system and secondly the adaptive system. The innate response is the first line of defence and relies on pattern recognition receptors (PRRs) to recognise specific pathogen associated molecular patterns (PAMPs) and provide a rapid response to the recognised pathogen. This system also has the complement system and phagocytic cells as its disposal. Pathogens expresses PAMPs which activate antigen presenting cells (APC), such as dendritic cells (DC), through ligation of PRR (e.g. Toll-like receptors) found on the APC surface. The adaptive immune system, is the specific response against the pathogens. This response begins with the activation of T-cells, CD4+ T-helper (TH) cells, CD8+ …show more content…
DC are crucial in pathogen recognition and initiating specific immune responses to destroy pathogens. DC phagocytose a diverse selection of antigens and present them to cells as peptides bound to MHC I/II products.
DCs can be immature or mature, immature DCs are found in tissues throughout the body allowing them to monitor the surrounding environment for pathogens and can provide a rapid response to any foreign bodies. DCs become mature when they receive a “danger” signal through PRRs, during the maturation process the cells T cell-stimulating capacity will increase, it will also increase in size allowing an increase in levels of cell surface antigens (e.g. MHC class I/II and CD40) which is important in T cell activation.
DCs will uptake the antigen causing inflammatory cytokines production (e.g. IL-2, INFµ, TNFα) and chemokines allowing the antigen loaded DC to migrate to lymphoid organs. Once there the naïve T cells have; the antigen that stimulated specific TCRs and polarising factors that determine which T-cell is produced - TH1, TH2 or TH17. The T-cells undergo structural changes so that they are programmed for apoptotic
Mature dendritic cells captures antigen and transports them to the lymph node, where they lose their properties and become immature dendritic cells that present antigens and activate naïve T cells.
Lymphocytes that become part of antibody-mediated immunity arm of the adaptive immune response develop in the:
The innate and adaptive immune response start with exposure to an antigen in the epithelium of
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Explain the involvement of immune cells (B, C, T, antigen presenting cells and immune complex).
this occurs in a series of steps, the first of which is incorporation of unidentified antigens by APCs in the epidermis and dermis. This process involves binding of the antigens to the MHC on the APC surface and the APC migrates to the lymph nodes. There, the APC binds reversibly and briefly with naïve or resting T cells through interactions between surface molecules located on both cells. Next, the MHC presents the antigen to a T lymphocyte receptor to begin activation of the T lymphocyte. The second signal for T lymphocyte activation is a non-antigen/ cell-cell interaction known as costimulation. If costimulation does not occur, the T lymphocyte will either undergo apoptosis or become unresponsive. Costimulation involves pairing of receptor with ligand on the T cell; these pairs include (LFA)-3 interacting with CD2, B7 interacting with CD28, and ICAM-1 interacting with LFA-1 (Lebwohl, 2003).
Immunology basically involves understanding the immune system and how it responds to various disease conditions. the immune system consists of a number of components. Traditionally, it is divided into humoral and cellular immune responses. It can also be distinguished into innate and adaptive immunity. The innate immunity can discriminate between normal tissues , self and newly encountered non-self-proteins while the adaptive immunity is the more complex system aimed at the eradication of intracellular pathogens. To do this, antigen derived from such pathogens that are often new to the host organism, need to be recognised by receptor-bearing specialised immune cells which respond to a complex system of stimulatory and costimulatory signals. Better understanding of the human immune system has led to the identification of a number of tumor-associated antigens in the 1980s and the development of various immunotherapeutic approaches. In recent years, identification of the specific antigenic MHC class I epitopes, advancements in genetic engineering, gene delivery, and cell-based therapeutic approaches allowed development of the novel immunotherapeutics.
The effector cells of the cellular immunity are responses from T-cell-mediated cells. The humoral effect on the immune systems is that the B cells recognize the antigen in the blood or the lymph. Once it recognizes the antigen, it is able to produce antibodies that are specific to the antigen, thus removing the antigen from the body. The B cells also create memory cells that will provide immunity to the antigen in the future. The cellular immunity’s effect on the immune response is the T cells recognize antigens. T cells are not able to bind with the antigens directly, so they require the assistance from MHC-bound peptides. Once the T cell is activated, the T cells produce gene products and create memory cells. T cell activation activates B cells as
The TH1 response is cell mediated and promotes inflammation while the TH2 response is an antibody response and anti-inflammatory. When excessive, the TH1 response can cause extensive tissue damage. TH1 responses are characterized by IFN-gamma production. IFN-gamma produces macrophage activity and causes B cells to create a coating of Abs. This creates a cell-mediated response. This is effective against invaders that are inside of the host cells. In a cell-mediated response, the APC phagocytizes the invader via macrophage, monocyte, or dendritic cell. Next, the antigen enters the lymphatic system via lymph node. The APC presents the antigen to T cells where the T cells recognize the antigen and cytokines are secreted to search and destroy
Women’s roles in society have become more equal to men’s and have overwhelmingly changed since the 1930s. There have always been influential women throughout history, however, their influential techniques have changed greatly. In the novel To Kill A Mockingbird by Harper Lee, women’s expectations, roles and opportunities, and their treatment can be compared to women today.
Cell-mediated reaction in which the signs appear 12 to 72 hours after exposure. Begins when APCs in lymph nodes display antigens to helper T cells. T cells secrete interferon and cytokines that activate cytotoxic T cells and macrophages. The result is a mixture of nonspecific and immune
The immune system is comprised of two responses: the adaptive immune response and the innate immune response. The first line of defence against invading organisms is classified as the innate immune response and the second line of defence and protection against re- exposure to the same pathogen is known as the adaptive immune response.
When a particular pathogen reinfected the body, it is met by an expansion of clonally selected cells, which has an antigen-specific memory toward the pathogen. This allows it to undergo much more rapid differentiation into effector cells when compared to the first antigen encounter. This result in a stronger and faster secondary immune response that eliminates the pathogen before it affects the body.
The academic study of the Hebrew Bible encompasses thousands of scholars from around the world. These scholars use various methods developed by other disciplines in order to study ancient texts along with other approaches that are distinctive to the biblical studies.
For the immune system to able to keep us healthy it needs to be able to recognise what is a danger to our body and therefore needs to be removed, and what is safe. Proteins are used to do this. Pathogens have proteins on their surface called antigens, which activate the immune system. Our own cells also have surface proteins which the immune system recognises as part of the body and therefore doesn’t attack. (1)