Interstitial Migration Of Lymphocytes.

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).

The organs that make up the lymphatic and immune system are the tonsils, spleen, thymus gland, lymph nodes, and lymphatic vessels. White blood cells (leukocytes), red blood cells (erythrocytes), plasma, and platelets (thrombocytes) make up the blood. Lymphocytes are leukocytes (white blood cells) that help the body fight off diseases. Two types of lymphocytes are B cells and T cells. Lymphocytes recognize antigens, or foreign substances/matter, in the body. Lymphocytes are a classification of agranulocytes, or cells (-cytes) without (a-) granules (granul/o) in the cytoplasm. B cells are created from stem cells, which are located in the bone marrow. B cells respond to antigens by becoming plasma cells. These plasma cells then create antibodies. Memory B cells produce a stronger response with the next exposure to the antigen. B cells fight off infection and bacteria while T cells defend against viruses and cancer cells. A hormone created by the thymus gland called thymosin changes lymphocytes into T cells. The thymus gland is active when you are a child and slowly shrinks, as you get older. T cells bind to the antigens on the cells and directly attack them. T cells secrete lymphokines that increase T cell production and directly kill cells with antigens. There are three types of T cells: cytotoxic T cells, helper T cells, and memory T cells.

Within the immune system, the thymus receives immature T cells from the bone marrow and turns them to mature T cells so that they can detect foreign substances. Antigens from epithelial cells are presented to the immature T cells. The T cells that recognize the antigens of the foreign cells continue to be tested and shown native cells from the body. If the T cells bind to the native cell, they are labeled autoimmune and destroyed, but those that

When the cell is inflamed the inflammation sends signals to integrins, which interact with proteins in the walls of the blood vessels. White blood cells then surround the inflamed tissue to fight infection as a result of integrin mediation.

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

For successful activation of a cytotoxic T lymphocyte (CTL), two signals are required from the antigen presenting cell (APC): Antigen presentation (T cell receptor binding to MHC1) and co-stimulation, CD28 on the CTL binds to co-stimulatory molecules; CD80/86 on the APC.

Detailed focus question: Cell migration is the movement of cells in a specific direction in order to perform a specific task. Cell migration is necessary in maintaining a healthy organism. In spite of this what type of outside factors prevent, slow down, increase, or enhance cell migration and why? How does this affect the organism overall?

The memory T cells can differentiate into Central memory T cells (TCM), effector memory T cells (TEM), or tissue-resident memory T cells (TRM). In addition, these memory T cells produce more IFN-gamma and other cytokines that recruit other effector cells. Also, CD4 T cell help is required for CD8 T-cell memory and involves CD40 and IL-2 signaling. The differentiation of Memory T cells into effector TH1 and CTLs cells can help eliminate this viral infection in the ways that I described in part (a).

A critical function of inflammation is to deliver neutrophils to the site of insult so the initiation of leukocyte activation can occur. The migration of neutrophils from the intravascular to extravascular space requires a

Healthy individuals have their immune system working properly to protect them from pathogens. Leukocytes are a part of the immune system that circulate in the blood (white cells). Lymphocytes are one subset of leukocytes that recognize and respond to their specific antigens (e.g.\ peptides from an external agent). T cells are a group of lymphocytes that mature in the thymus. Under exposure to their specific antigen, conventional T cells are activated, leading to secretion of growth cytokines (predominantly interleukine 2, denoted IL-2), and expression of the interleukine 2 receptor which triggers cytokine driven proliferation \cite{deboer87,thornton98,BOP2006}. However, the immune system can cause damage by targeting erroneously self antigens

The Infection Fighter B cells and T cells are two important components of the immune system. They play a role in the inflammation associated with lupus. Both B cells and T cells associate immune cells called lymphocytes. Lymphocytes help fight infection. B cells and T cells are involved in the immune system's response to infection. Antigens are foreign bodies (such as bacteria and viruses) that stimulate the immune system to produce autoantibodies. When a T cell recognizes an antigen it will produce chemicals (cytokines) that cause B cells to multiply and release many immune proteins (antibodies). These antibodies circulate generally in the bloodstream, recognizing the foreign particles and triggering

Cell-mediated immunity is part of the immune system that uses specific cells, such as cytotoxic (which is the primary cell responsible for the cell-mediated immunity), as well as memory, helper and suppressor T-cells instead of antibodies which are activated by MHC proteins (as seen in B-cells). They are produced in red bone marrow and recognize infected cells and have the ability to activate B-cells and T-cells. When specific antigens present themselves they are able to destroy them. Antigens being, small protein fragments that are at the cell surface which create an adaptive immune response. T-cells mature in the thymus where they develop immunocompetence and

2)to give an overview of the current state-of-the-understanding of the implications associated with host macrophage responses in regenerative medicine.

The triggering of the T-helper cell leads to a various pathways that can result in immunoglobulin class switching and antibody production, macrophage action through direct contact. The T-helper cell response delimited by two distinct pathways involves two different subtypes of T-helper cells- the T-helper1 and T-helper2 cells. T-helper1 cells are directed for intracellular microorganisms such as bacteria and parasites by means of the initiation of macrophages, whereas T-helper2 cells induce antibody production in B cells, to counteract extracellular pathogens and toxins. As soon as T-helper cells are activated, they distribute quickly and discharge cytokines to increase or police immune responses

are activated after exposure to specific pathogens, and depended upon lymphocytes that recognize and respond to specific invading pathogens.