Immune system. B cells and T cells. B cells and T cells. Immunoglobulins. Immunoglobulins. Immunoglobulins (antibodies) stem cell

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Egbert Lindsey
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1 Immune system - many different types of cells mediate the to destroy bacteria and viruses as well as pre-cancerous cells - all cells in the immune system, as well as all the red blood cells, arise from totipotent stem cells in the bone marrow r.b.c cells and cells myeloid progenitor stem cell lymphoid progenitor stem cell cells and cells pre cell cell Effector cells lymphoid progenitors cell Plasma cells pre cell Immunoglobulins (antibodies) cell Effector cells IgA, IgE, IgG cell Plasma cells IgA, IgE, IgG, IgM Immunoglobulins lass [IgX]/ml structure function IgG 12 mg K 2 2 bind antigens which invade body IgA 1 mg K 2 2 in tears, saliva, mucus; resp., intestinal tracts Immunoglobulins lass [IgX]/ml structure function IgM 1 mg K 2 2 immature Ab IgD 1 mg K 2 2 unknown IgE * K 2 2 -stimulates mast cells * IgE levels are elevated during allergic response to release histamine

2 Immunoglobulins (antibodies) - antibody molecules (Ab) are large globular proteins located on surfaces of lymphocytes light chain heavy chain Antibody structure L L variable region - oligo saccharide chains of specific seq. of sugars is attached to some a.a., generally asn, ser and thr residues carbohydrate constant region Light chains Heavy chains 109 HO chains 1 variable 109 constant 214 a.a. seq. a.a. seq. - variable a.a. sequence is different in each antibody - constant a.a. sequence is same in each antibody 1 variable constant 446 a.a. seq. a.a. seq. - variable a.a. sequence is different in each antibody - constant a.a. sequence is same in each antibody Functions of different regions 1. variable region = site of antigen binding - hypervariable segments of both chains are extremely variable in a.a. sequences Functions of different regions 2. constant regions - recognize cell membrane glycoproteins of host cells antigen binding site recognizes host cell membranes antigen binding site oligosaccharide chains

3 Immunogenetics Healthy adults have about 500,000 different antibody molecules circulating in blood. - each antibody has a unique H chain and L chain Is there one gene for each unique H protein and L protein in the human body? O! Does a new antigen (foreign protein) cause a new antibody to be formed specifically against it? O! Different regions of the different V,D,J and genes in the DA of lymphocytes are selected A RADOM to form the mra. DA Heavy chain formation in cell V genes D J genes genes genes 10 families genes his mra is modified and translated into an immature antibody protein (Ab). DA joining randomly selected V, D, J and regions new gene for antibody Formation of heavy chain mra DA RA polymerase removal of intervening sequences V D J gene for antibody immature m RA m RA Modifications are made to nascent protein (pre-pro IgG Heavy chain) 1. -terminal seq. is removed at membrane 2. 2 H chains and 2 L chains associate 3. sugars are added

4 lonal selection theory of lonal selection theory of 1. RADOM selection of specific V, D, J, and genes to produce recombinant gene for antibody 2. Each mature lymphocyte produces only OE specific antibody protein. lonal selection theory of 3. Mature cells die unless activated by an antigen binding to V region cell - V region of antibody projects out of cell membrane lonal selection theory - each Ab protein recognizes a specific chemical grouping on antigen surface - if antigen binds Ab, then cell divides rapidly producing millions of cell clones cells cells Immune repertoire Many different antibodies are formed against one virus coat or one bacterial cell wall. Antigens such as virus coat proteins and bacterial cell walls may be bound by different antibodies. ew viruses and bacteria are usually bound by one or more old antibodies. one marrow Immune system otipotent stem cells are dividing continuously and the daughter cells are differentiating into red and white blood cells.

5 bone marrow lymph tissue bone marrow lymph tissue virus Antigen independent Antigen dependent Antigen independent Antigen dependent bone marrow Antigen independent lymph tissue AIDS virus kills helper cells Antigen dependent ypical pattern of immune dysfunction after HIV infection 1000 concen. cells months after infection utrition and the Immune system - folate, vitamins, E, -6 and -12 are essential for optimal functioning of immune system - also a moderate to high protein diet increases immune efficiency Deficiencies and decreased deficiency of vitamin -6 causes reduced stimulation of lymphocytes by antigens u++ and Zn++ deficiencies lead to decreased number of lymphocytes deficiency of vitamins A, and E result in impaired -cell mediated immunity

6 ancer and immune surveillance - pre-cancerous cells arise in all humans every day - most pre-cancerous cells are identified by cells of the immune system and are destroyed before dividing ancer risks for Americans Risk factors for cancer Deaths / yr. per million Amer. alcohol abuse 714 food additives 612 diet quality 143 industrial waste 82 occupational hazards 61 pollution 41 sexual behavior < 20 tobacco use < 20 ancer risks for Americans Risk factors for cancer Deaths / yr. per million Amer. 1. diet quality (anti-oxidants) tobacco use sexual behavior alcohol pollution industrial waste occupational < food additives < 20

Name (print) Name (signature) Period. (Total 30 points)

Name (print) Name (signature) Period. (Total 30 points) AP Biology Worksheet Chapter 43 The Immune System Lambdin April 4, 2011 Due Date: Thurs. April 7, 2011 You may use the following: Text Notes Power point Internet One other person in class "On my honor,