Chapter 32. Non specific (Innate) Host Resistance ( 비특이적 ( 내재 ) 숙주방어 )

Transcription

1 Chapter 32 Non specific (Innate) Host Resistance ( 비특이적 ( 내재 ) 숙주방어 )

2 Host Resistance Overview Immune system ( 면역계 ) Composed of widely distributed cells, tissues, and organs Recognizes foreign substances or microbes and acts to neutralize or destroy them Immunity ( 면역력 ) Ability of host to resist a particular disease or infection Self ( 자기 ) 와 non self ( 비자기 ) 의구분 Immunology ( 면역학 ) Science concerned with immune responses 2

3 Host Resistance Overview Most pathogens (disease causing microbes) Must overcome surface barriers and reach underlying Overcome resistance by host Non specific resistance ( 비특이면역반응 ) Specific immune response ( 특이면역반응 )

4 Non specific immune response ( 비특이면역반응 ) Non specific resistance ( 비특이저항 ) Innate ( 내재 ) immunity Natural ( 자연 ) immunity Acts as a first line of defense Offers resistance to any microbe or foreign material Lacks immunological memory ( 면역기억 ) 4

5 Specific immune response ( 특이면역반응 ) Specific ( 특이 ) immunity Acquired ( 획득 ) immunity Adaptive ( 적응 ) immunity Resistance to a particular foreign agent Has memory ( 기억 ) Effectiveness increases on repeated exposure to agent

6 Antigens ( 항원 ) Recognized as foreign Invoke immune responses Presence of antigen in body ultimately results in B cell activation Production of antibodies ( 항체 ) Antibodies bind to specific antigens, inactivating or eliminating them

7 White Blood Cells of Innate and Adaptive Immunity White blood cells (WBCs, 백혈구 ) play a major role in the innate and specific responses Hematopoesis ( 조혈 ) Development of white blood cells in bone marrow ( 골수 ) of mammals

8 First group of WBCs Macrophages ( 대식세포 ) and dendritic cells ( 수지상세포 ) Mature prior to leaving bone marrow Become part of innate immune system Respond to all antigens

9 B and T cells Second group of WBCs Not fully functional after leaving bone marrow Become part of the adaptive immune response Could differentiate ( 분화 ) in response to specific antigens

10 Physical Barriers ( 물리적장벽 ) in Non specific (Innate) Resistance Skin ( 피부 ), mucous membrane ( 점막 ), respiratory system ( 호흡계 ), gastrointestinal tract ( 위장관 ), genitourinary tract ( 비뇨생식관 ), and eye Along with host s secretions (flushing, 씻어내려는기전 ), these barriers are the first line of defense against microbes

11 Antimicrobial Secretions Lysozyme Hydrolyzes bond connecting sugars in peptidoglycan Lactoferrin Secreted by activated macrophages ( 대식세포 ) and polymorphonuclear leukocytes ( 다형핵백혈구 ) Sequesters iron from plasma leading to iron deficiency Lactoperoxidase Produces superoxide radicals

12 Chemical Mediators in Nonspecific (Innate) Resistance Gastric juices ( 위액 ), lysozyme, and urea Antimicrobial peptides ( 항미생물펩타이드 ) Cationic peptides ( 양이온펩타이드 ) Damage bacterial plasma membranes

13 Complement System ( 보체계 ) Composed of >30 serum proteins C1 recognition unit C2, C3 (C3a & C3b), and C4 activation unit C5, C6 C9 membrane attack unit Augments (or complements ) the antibacterial activity of antibody

14 Complement Activation Produced in inactive forms Activated following enzymatic cleavage Must be activated in cascade ( 폭포 ) fashion Three pathways of activation Classical Alternative Lectin

15 Functions of Complement System Inflammation ( 염증 ) Attraction of neutrophils ( 호중구 ) Opsonization ( 옵소닌화 ) Cell lysis ( 세포용해 )

16 Opsonization ( 옵소닌화 ) Process in which microbes are coated by serum components in preparation for recognition/ingestion by phagocytic cells ( 식세포 ) Opsonins Molecules that carry out above Complement protein, C3b is an opsonin Bind to microbial cells, coating them for phagocyte recognition

17 Opsonization ( 옵소닌화 )

18 Cytokines ( 싸이토카인 ) Soluble proteins or glycoproteins that are released by one cell population that act as intercellular mediators or signaling molecules Four families Chemokines, hematopoietins, interleukins, and tumor necrosis factor (TNF) family

19 Cytokines ( 싸이토카인 ) Monokines Released from mononuclear phagocytes ( 단핵성식세포 ) Lymphokines Released from T lymphocytes Interleukins Released from one leukocyte and act on another leukocyte Colony stimulating factors (CSFs) Stimulate growth and differentiation of immature leukocytes in bone marrow

20 Cytokines ( 싸이토카인 ) Cytokine production is induced by nonspecific stimuli (infection), inflammation, T cell antigen interactions Autocrine function Affect same cell responsible for their production Paracrine function Affect nearby cells Endocrine function Spread by circulatory system to distant target cells

21 Cytokines Biological Effects Must bind to specific receptors on target cells Many activities in differentiation, proliferation, apoptosis Chemokines Stimulate chemotaxis ( 주화성 ) and chemokinesis ( 화학운동성, direct cell movement)

22 Functions of Cytokines

23 Interferons ( 인터페론 ) Regulatory cytokines produced by some eukaryotic cells in response to viral infection Do not prevent virus entry into host cells, but defend against viruses by preventing viral replication and assembly Also help to regulate the immune response

24 Interferon ( 인터페론 )

25 Endogenous Pyrogens ( 내인성발열인자 ) Cytokines that elicit fever in the host Fever In adults Oral ( 구강 ) temperature > 37 C Rectal ( 직장 ) temperature > 37.5 C Most common cause of fever is viral or bacterial infection or bacterial toxins 25

26 Endogenous Pyrogens Production of IL 1, IL 6, tumor necrosis factor (TNF) by macrophages in response to pathogenic microbes Pyrogens moves to hypothalamus ( 시상하부 ) Induce production of prostaglandins Reset hypothalamus to a higher temperature 26

27 How Fever Augments Host s Defenses Stimulation of leukocytes so they can destroy pathogen Enhances immune system activity Enhances microbiostasis (growth inhibition) by decreasing available iron to microbes Hypoferremia ( 저철분증 ) decreased iron availability Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. 27