2&3innateimmunity

2&3innateimmunity - Innate Immunity Lectures 2 and...

Info icon This preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Innate Immunity Lectures 2 and 3, Chapter 2 MMI 188 Human Immunology José V. Torres, Ph.D. Professor Medical Microbiology & Immunology School of Medicine University of California Davis, CA 95616 [email protected] 530 752-3157; 3134 Tupper Hall
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Damage by Pathogens: 1. Exotoxins via cell surface receptors 2. Endotoxin release causing secretion of cytokines by phagocytes 3. Direct killing of cell
Image of page 2
Different compartments of the body are exploited by pathogens Different innate immune system components used on defense
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Complement System of blood proteins Cascade that results in covalent bonding of protein fragments to the pathogen’s surface Phagocytes have receptors for these fragments Uptake and destruction of pathogens by macrophages and neutrophils Complement complex makes holes on the cell membranes of pathogens Three complement activation pathways: Alternative Triggered by changes caused by bacterial surface components Lectin Binding of complement to peptidoglycans on microbes Classical Antibody bound to pathogen triggers complement activation
Image of page 4
Complement Complement components are plasma proteins Made in the liver More than 30 proteins Some circulate as enzyme zymogens The 3 pathways are triggered in different ways All converge in the same reaction C3 is the most abundant component in plasma C3 cleavage into C3b and C3a Covalent binding of C3b to the surface of pathogens ( complement fixation ) Tags pathogen for destruction by phagocytes Starts the cascade that damages the pathogen’s membrane • Soluble C3a recruits inflammatory cells Inherited deficiency of each complement component has been described C3 deficiency is the most severe (bacterial infections)
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Complement Activation -Proteolytic cleavage of complement component C3 -Large C3b fragment becomes covalently attached to pathogen - C3b labels the pathogen as dangerous - C3a attracts phagocytic cells
Image of page 6
Reactive thioester bond; Covalent binding to hydroxyl and amino groups
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
3 Pathways of Complement Activation
Image of page 8
Initiation of Alternative Pathway of Complement - C3 hydrolyses near microbe - Activated C3 binds Factor B - Factor D cleaves Factor B producing the soluble convertase, iC3Bb - This convertase cleaves C3 into C3b and C3a - C3b binds to microbe - C3a attracts phagocytes
Image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
- C3b binds Factor B - Factor D cleaves Factor B to produce C3bBb, the surface bound convertase - C3bBb cleaves C3 - More C3b is produced and binds to microbe - C3a attracts phagocytes Amplification
Image of page 10
C3bBb Bb fragment of Factor B cleaves C3 C3b fragment of C3 holds the enzyme at the surface of the pathogen
Image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Pathogen surface: C3bBb stabilized by properdin Factor H binding induces conformational change of C3b Factor I cleaves C3b DAF and MCP block complement fixation on human cells Complement control proteins
Image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern