Chapter 11

Question 1

• through recognition of specific patterns found on the surface of organisms and toxins, the body’s immune system can distinguish itself from these foreign substances and tell the difference between potentially harmful and nonharmful agents
• skin and its epithelial layers in conjunction with the body’s normal inflammatory processes make up the body’s first line of defense and confer innate or natural immunity
• adaptive immune response-occurs once the first line barriers have been crossed; develops slowly over time but results in the development of antibodies

Answer 1

Immunity

Question 2

• short-acting biologically active, soluble substances
• essential competent of host defense mechanisms and the primary means with which cells of innate and adaptive immunity communicate
• responsible for directing the migration of leukocytes to both areas of injury and locations where immune responses have been activated (spleen, Peyer patches, tonsils, lymph nodes)
• work by binding to specific receptors on the cells that they target and then activating intracellular processes
• all are secreted in a brief, self limited manner
• rarely stored as preformed molecules but instead are synthesized when the cells that produce them are activated
• exhibit redundancy; ability of different cytokines to stimulate the same or overlapping biologic functions
• can also function to initiate cascade reactions with one cytokine influencing the synthesis and actions of other cytokines; produce the desired action, effects may be localized

Answer 2

Cytokines

Question 3

• involved in immune and inflammatory cellular responses and function to control the migration of leukocytes to their primary site of action in the immune response
• 4 distinct classes
  
  • C
  • CC: attract monocytes, lymphocytes, and eosinophils to site of chronic inflammation
  • CXC: attract neutrophils to sites of acute inflammation
  • CX3C
• capable of activating different populations of leukocytes based upon the needs of the situation
• binding of a chemokine to a receptor can result in inhibition or activation with the same chemokine acting as an activator at one type of receptor and as an inhibitor at another
• implicated in the development of a number of acute and chronic diseases
  
  • atherosclerosis, rheumatoid arthritis, inflammatory bowel disease (Crohn’s, ulcerative colitis), allergic asthma and chronic bronchitis, multiple sclerosis, systemic lupus erythematosus, and HIV infection
• play a role in the body’s immune response against cancer cells

Answer 3

Chemokines

Question 4

• intact skin is by far the most formidable physical barrier available to infection because of its design
• skin has simple chemicals that create a nonspecific, salty, acidic environment and antibacterial proteins that inhibit the colonization of microorganisms and aid in their destruction
• when pathogens are able to breach the epithelial defenses, the innate immune response is initiated by the body’s leukocytes, which recognize common surface receptors present on the invading microorganisms

Answer 4

Epithelial barriers

Question 5

• recognize microbes that share characteristics common to all of their surface receptors
• key cells:
  
  • Neutrophils and Macrophages:
    - neutrophils are the most abundant granulocytes found in the body
    - 55% of all white blood cells
    - phagocytic cells and are capable of amoebiod like movement
    - early responder cells in innate immunity
    - lay predominantly dormant in the blood and bone marrow until needed
    - macrophages are the largest in size of all white blood cells
    - only make up 3%-7% of the total leukocyte count
    - released from the bone marrow into the bloodstream, migrate to tissues
    - long life span, reside in tissues, and act as the first phagocyte that invading organisms encounter upon entering the body
    - can remove antigen-antibody complexes
  • Dendritic Cells:
    - specialized, bien marrow derived leukocytes found in lymphoid tissue and are the bridge between innate and adaptive immunity systems
    - relatively rare cells that are found mainly in tissues exposed to external environments
    - responsible for the processing and presentation of antigens to the lymphocytes
    - release several communication molecules that direct that nature of adaptive immune responses
  • natural killer cells and intraepithelial lymphocytes
    - NK cells have the innate ability to spontaneously kill target organisms
    - heterogeneous population of lymphocytes that mediate spontaneous cytotoxicity against infected cells
    - considered to be part of the innate immune response
    - capable of killing some types of tumor and/or infected cells w/o previous exposure to surface antigens
    - play important role in limiting the spread of infection and assisting in the development of adaptive immune responses through the production of cytokines
    - can be excitatory or inhibitory; ensures that only foreign cells are destroyed
    - comprise 10%-15% of peripheral blood lymphocytes

Answer 5

Cells of innate immunity

Question 6

• innate immune response plays a crucial role in the proinflammatory response to infection and relies upon the ability of host defenses to differentiate self from nonself so that only invading organisms are targeted
• leukocytes involved, recognize certain evolutionary retained patterns present on the surfaces of pathogens and in response bind to its membrane and destroy the invading organism through the process of phagocytosis
• the ability of the innate immune response to limit microbes early in the infectious process results from the binding of pathogens to the PRPs on leukocytes

Answer 6

Pathogen Recognition