Class 2 Mhc Case Study

The immune system is made up of several types of cells that work together to fight infections. Lymph cells (called lymphocytes) are the main type of cell in the adaptive immune system. There are 2 types of lymph cells: T cells and B cells. When B cells respond to an infection, they change into plasma cells. The plasma cells are found mainly in the bone marrow—the soft, inner part of some bones. The plasma cells

Active immunizing agents stimulate the body to make its own antibodies and to continue on making them, the

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.

The antigens in a vaccine are recognized by lymphocytes and lead to development of memory cells.

MHC restriction means that T cells can only recognize the Ags that are presented by their own MHC molecules. After an invader enters a cell, it is broken down to an antigen and is brought to the cell to be presented to T cells by the major histocompatibility complex (MHC) class I or class II. When T cells develop, they go through a selection in thymus so that the TCR will not recognize self, meaning that the TCR will not recognize and MHC that is presenting a self-antigen. More in-depth, immature T cells that are found to be able to recognize invaders on self MHCs are kept, but others that will not be of any use or recognize self-antigens will result in programmed cell death. Because a TCR will only recognize certain MHCs and not others, this is the definition of MHC restriction. The MHC restriction comes from the thymus that you were born with rather than genes. This was shown through an experiment with transgenic mice. They showed that the transgenic T cells matured in the thymus and went into the peripheral lymphoid organs. This only occurred if the mouse had the same allelic form of the MHC recognized by the TCR. If the mouse didn’t have the match between MHC and TCR the T cells died in the thymus. This showed that the

Graft rejection: Type IV hypersensitivity. Type IV hypersensitivity is a delayed hypersensitivity as the reaction takes more than 12 hours. It is mediated by T helper cells and cytotoxic T cells and does not involved antibodies. In graft rejection, the rejection is caused by foreign MHC antigens as the T cells responds to them by attacking the foreign MHC antigens when they are being recognized. Rejection also only takes place after a few hours to months and years depending on the type of

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 adaptive immunity required and acquires a memory response, which includes lymphocytes (T and B cells), host defense against specific pathogens that can be obtain through a specific antibodies and T cells, slower response to specific recognition of microbe.

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

Human leukocyte antigen (HLA) class II molecules DR3 and DR4 are strongly associated with type 1 DM. Above ninety percentages of white people with type 1 DM express one or both of those molecules, compared with fifty to sixty percenatges of the all people (Infante et al., 2001).

When it attaches to an antigen, it reels that antigen in and clones itself and makes an army of B lymphocytes to fight at one specific antigen. Some become Effector cells, Memory cells, or more B lymphocytes. The humoral response allows your body to achieve immunity by encountering pathogens either randomly or on purpose. The last and final defense are called the Cellular immune response. There are different names for these types of white blood cells and they are called T cells. The different type of T cells is Helper T cells, Cytotoxic cells, Memory T cells, Suppressor T cells, regular and lastly, Neutral killers. Helper T cell can’t fight diseases but can call other cells that can fight diseases. Cytotoxic cells can kill diseases or cells that are infected or cancerous. Helper T cells use something called cytokines to alert other Helper T cells, which then make more Helper and Memory T

The response phase begins with antigen presenting cells, such as dendritic cells and macrophages, found in the airway. These cells will capture, process and present allergens to helper T cells (Th cells.) Th cells become activated and release cytokines. The allergen promotes eosinophil recruitment as well. [4]

Positive selection: Positive selection permits the survival of only those T cells whose T cell receptors (TCRs) are capable of a self MHC restricted repertoire of T cells. Cells that fail positive selection are eliminated within the thymus by apoptosis. Negative selection: Negative selection eliminates T cells that react too strongly with self MHC or with self MHC and self-peptides bearing high affinity receptors for self MHC molecules alone or self-antigen presented by self-MHC, which results in self-tolerance. It is an extremely important factor in generating a primary T-cell repertoire that is

TH-17 cells are the more recently described T Helper lymphocyte subsets. They are differentiated from naïve CD4 cells after