lecture8

lecture8 - 3.051J/20.340J 1 Lecture 8 Cell-Surface...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
1 3.051 J / 20 .340 J Lecture 8: Cell-Surface Interactions: Host Responses to Biomaterials (Part II) Implantation of a biomaterial initiates the inflammatory response: - response of vascularized tissue to local injury - severity indicates biocompatibility of material Cooperative Signaling Cascades: 1. Coagulation Cascade initiated by adsorbed 2. Complement Alternative Pathway proteins The complement is a component of the immune system. Immune system function : to protect against pathogens Innate (Native) Immunity Adaptive (Aquired) Immunity - first line of defense - specificity to distinct foreign biomolecules (antigens) - nonspecific response to invading pathogens - memory of exposure - elicits adaptive response Physical/chemical barriers: Blood proteins: epithelia, antimicrobial proteins antibodies (immunoglobulins), cytokines Blood proteins: complement; cytokines (regulatory) Cells: lymphocytes (T cells, B cells) Cells: phagocytes (macrophages, neutrophils), natural killer cells
Background image of page 1

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

View Full DocumentRight Arrow Icon
2 3.051 J / 20 .340 J Complement - system of >30 proteins that mediate immune response - discriminates “foreign” from “self” through adsorbed proteins/ protein fragments (C3b, C4b) - recruit and activate phagocytes (C3a, C5a) - lysis of pathogens via membrane pore formation (C5b, C6-C9) 3 recognized pathways (to C5 convertase) Classical pathway: antigen-antibody immune complex (IC) binds and activates C1 (autocatalytic proteolysis) initiating an enzymatic cascade C1 C1s C4 C4b C2 C2b C3 C3b C5 C5a/C5b soluble fragment (16 kDa): insoluble fragment (170 kDa): recruits phagocytes by chemotaxis initiates membrane attack complex (MAC) C5b C6 C7 C8 C9 MAC pore formation compromises bacterial cell membrane
Background image of page 2
3 3.051 J / 20 .340 J Lectin pathway (discovered in 1990’s) : mannan binding lectin (MBL) bacteria cell wall binds carbohydrates on pathogen (gram negative) MBL-associated serine proteases (MASP-1, -2) complexes with MBL activated MASP’s cleave C4 C4b remaining cascade follows classical pathway Alternative pathway: nonselective pathway of complement (any foreign surface) C3 C3b occurs continuously in plasma at low frequency C3b adsorbs on foreign surfaces (biomaterial) cofactor B C3b Bb complex amplifies C3 C3b C 3 b C3b Bb complex C 5 C5a/C5b Soluble complement protein fragments C3a and C5a recruit phagocytes to site of injury
Background image of page 3

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

View Full DocumentRight Arrow Icon
4 3.051 J / 20 .340 J Inflammatory Response to Implanted Biomaterials
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/11/2011 for the course BIO 2.797j taught by Professor Matthewlang during the Fall '06 term at MIT.

Page1 / 13

lecture8 - 3.051J/20.340J 1 Lecture 8 Cell-Surface...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online