Phagocytic Cells = cells that ____________________ =any foreign molecule recognized by a lymphocyte (B or T cell) a) most are proteins or polysaccharides b) may protrude from microbe membrane c) eptiope = tiny part the lymphocyte binds

= major histocompatibility complex ________________that code for MHC molecules All are : Class I MHC display ________________ synthesized within the cell (cancer/virus) found on most body cells Class II MHC display peptides that are: found on phagocytic cells & B cells

* Helper–T cells Type of T cell that binds to : (Class II MHC molecules) Helps promote : Promote Humoral (B-cell) response by : Promote cell mediated-response by:

External Defenses 1) Skin…waterproof layer dead cells 2) Linings of body tubes/cavities a) b) c) d) 3) Neutral/beneficial bacteria population

Internal Defenses I. present at birth, always present II. activated by microbes/antigens a) Require self-recognition (membrane proteins) b) only present in Vertebrates

I. Innate Immunity A) Antimicrobial proteins B) inflammatory response C) Systemic response D) Phagocytic Cells

A) Antimicrobial Proteins 1) interferon ά and β secreted by virus-infected cells help neighboring cells inhibit viral reproduction 2) complement system = 30 serum proteins a. microbe presence triggers cascade b. cascade activates complement system c. system causes microbe to lyse & triggers inflammation (may also be activated by antibodies*)

B) Inflammation Triggered by chemical signals like histamine Complement system, allergen, antigen or injury cause mast cells to release histamine Histamine dilates capillaries, lets out more clotting elements, anti-microbial proteins ___________________ released by capillary attract phagocytes Clotting blocks spread of microbes

C) Systemic Response Widespread response Increased WBC production Fever – ___________________________ Septic shock – bacterial infection causes high fever low bp may cause death

D) Phagocytic cells (4 types) 1) neutrophils – 2) macrophages – 3) eosinophils – 4) dentritic cells – activate acquired immunity a) b) c) d) e)

II aquired/adaptive immunity A) Humoral Response = B) Cell Mediated Response = infected cells Cancer cells Transplanted cells

Antibodies Proteins secreted by differentiated B-cells (plasma cells) Bind to specific antigen Also called Immunoglobulins (Ig) 1) IgG – 2) IgA – 3) IgE –

Humoral Response = B cells put antibodies in fluid (humor) 1. B cell receptor binds to a Polysaccharide or protein on microbe, pollen or transplanted cell 2. B cell takes in antigen and presents it on MHC surface protein to attract : 3. Helper T binds to MHC-antigen complex and begins secreting : 4. cytokines induce mitosis in B cell to produce a. b.

Plasma cells make antibodies specific to the antigen that their parent B-cell bound 1.bind & clump viruses/bacteria 2. percipitate antigens dissolved in fluid 3. activate complement proteins Memory B-cells stay in blood stream ready to become activated in :

Cell Mediated Response =fights cancer, infected cells, transplant cells 1. Class I MHC molecule displays antigens that are : 2. Cytotoxic Tcells bind to MHC-antigen complex (CD8 protein ropes them together) 3. Binding makes cytotoxic Tcell secrete: a. (protein, makes holes in membrane) b. c.

More on Helper T Cells Helper T cells Activate by 1. binding on dendritic cells, macrophages, or B-cells 2. Makes : a. cytotoxic T cells to become active b. B cells to begin clonal selection….. mitosis to produce :

Helper T clonal selection Activated helper T does mitosis 1 clone divides to make many: The other divides to make :

Lymphocyte receptor diversity 1 million diff. B cells….10 million diff. T cells When leukocytes differentiate into lymphocytes 1. Recombinase enzymes link : 2. DNA between selected segments is deleted 3. receptor gene made of V seg + J seg + an intron and a constant segment. 4. that protein makes the 5.