Test Lab Iii

Homework III Prof.Sudad Saman Hoa Le

1/explain the immune response process include all cell involved in this process: The immune response is triggered by the presence of an antigen: the response includes cell-mediated and antibody mediated defense. T cell and cell –mediated immunity. Foreign antigens must generally be processed by other cells (typically macrophages) and incorporated into cell membranes (antigen presentation) before the antigens can activate lymphocytes. All body cells have membrane glycoprotein. The genes controlling their synthesis make up a chromosomal region called the major histocompatibility complex (MHC). The membrane glycoproteins are called MHC protein. Lymphocytes are not activated by lone antigens but will respond to an antigen bound to either a class I or a class II MHC protein. Class I MHC proteins are in all nucleated body cells .class II MHC proteins are only in antigen-presenting cells (APCs) and lymphocytes. Whether a T cell responds to antigen held in Class I or II MHC proteins depends on the structure of the T cell membrane. T cell membranes contain protein called CD (cluster of differentiation) marker. CD 3 makers are present on all T cells.CD8 makers are on cytotoxic and suppressor T cells.CD4 makers are on all helper T cells. Cell-mediated immunity (cellular immunity) results from the activation of CD8 T cell by antigens bound to Class I MHCs. When activated, most of the T cell divides to generate cytotoxic T cells and memory Tc cells, which remain on reserve to guard against future such attacks. Suppressor T cells depress the responses of other T cells and of B cells. Helper, or CD4, T cells respond to antigens presented by class II MHC proteins, when activated; they secret lymphokines that help coordinate specific and nonspecific defenses and regulate cell -mediated and immunity. B cells and antibody- mediated immunity: B cells become sensitized when antigens bind to their membrane antibody molecules. The antigens are then displayed on the Class II MHC proteins of the B cells, which become activated by helper T cells activated by the same antigen. An active B cell may differentiate into plasma cells or produces daughter cells that differentiate into plasma cells and memory B cell. Antibodies are produced by the plasma cells. An Antibody molecule consists of two parallel pairs of polypeptide chains containing constants and variable segment. When Antibody molecules bind to an antigen, they form an antigen-antibody complex. Effect that appear after binding include neutralixation (antibody binding such

that viruses or bacterial toxins cannot bind); precipitation (formation of an insoluble immune complex) and agglutination (formation of large complexes); opsonization (coating of pathogens with antibodies and complement proteins to enhance phagocytosis); stimulation of inflammation; and prevention of bacterial or viral adhesion. The five classes of antibodies in body fluids are immunoglobulin *G(IgG):responsible for resistance against many virus, bacterial toxins *E(IgE),which releases chemicals that accelerate local inflammation *D(IgD),located on the surfaces of B cells *M(IgM)the first antibody type secreted after the antigen arrives *A(IgA)found in glandular secretions 2/Define Opsonins: Is a molecule that acts as a binding enhancer for the process of phagocytosis. After the binding, bacteria, dead tissue cells and small mineral particles or example are easily engulfed. The effect is called opsonization. 4/Explain what are protease inhitors:

Protease inhibitors are a class of medication used to treat or prevent infection by viruses, including HIV and Hepatits C. Protease inhibitors prevent viral replication by inhibiting the activity of HIV-1 protease, an enzyme used by the viruses to cleave nascent protein for final assembly of new virons/ Protease inhibitors have been developed or are presently undergoing testing for treating various viruses. 5/Explain what is a hapten, give example of some Hapten is a small molecule that reacts with a specific antibody but cannot induce the formation of antibodies unless bound to a carrier protein or other large antigenic molecule. when attaching to large molecules, function of hapten is as complex antigens. An example of a hapten is mentioned which is urusshiol, it is the toxin found in poison ivy. 3/Draw and label Antibiotic molecule: