Erstellt von Maryam Nasir
vor mehr als 6 Jahre
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Frage | Antworten |
first line of defence | intact skin + mucus membrane |
second line of defence | innate immunity |
innate immunity | 1. not specific 2. rapid 3. preformed 4. fully active |
third line of defence | adaptive immunity |
adaptive immunity classification | cell-mediated and humoral/antibody-mediated |
antibody functions | Opsonization neutralize toxins & viruses complement fixation prevent attachment of microbes catalytic ability |
Cell mediated immunity is for | inhibiting fungi, parasites, intracellular bacteria kill virus infected cells kill tumor cells (new antigens) |
Adaptive immunity characteristic | Specific Memory Diverse |
Bridge b/w adaptive & innate immunity | macrophages + dendritic cells |
first step of adaptive immunity activation | presentation of antigens to Th cells by APCs |
Origin of host defences | recognition by specific immune cells activation of immune cells response that targets the offender |
Which antigen activates B cells directly? | bacterial polysaccharides (T cell independent antigens) |
T cell independent antigens | only IgM is produced |
functions of B cells (during induction process) | present epitopes to Th cells (IgM receptor) |
IgM receptor recognizes what compounds | CHO, lipids, DNA, RNA, foreign proteins |
MHC II of B cells | recognize only peptide fragments |
INNATE IMMUNITY | exists prior to exposure, non specific no improval after exposure no memory kill microbes activate adaptive immunity |
host defences of innate immunity | 1. Barriers 2. Cells 3. Proteins 4. Processes (inflammation, phagocytosis) |
Recognition by innate arm | pattern recognition receptors- recognize PAMPs |
Innate arm receptors on surface of cells | TLR + Mannan binding lectin receptors |
Innate arm receptors inside the cytoplasm | NOD + RIG-I helicase receptors |
Toll Like Receptors (TLR) | 10 receptors Location: Macrophages, dendritic cells, mast cells |
TLR Function | activate transcription factors, which increase production of proinflammatory cytokines |
TLR-4 | recognizes LPS (gram -ve bacteria) LPS binds to LPS binding protein in plasma; LPS transferred to Macrophages surface receptor CD14 LPS stimulates TLR 4 |
Function of TLR 4 | transmission of signals to nucleus to induce sysnthesis of IL 1, IL 6, IL 8, TNF, & B7 (costimulator) |
TLR 2 | recognize Gram +ve bacteria & yeast |
Mannan binding lectin | recognizes mannan on bacteria & yeast |
Location of MBL (mannan binding lectin) | dendritic cells & macrohages |
Function of MBL | activation of Complement system enhancement of phagocytosis In Acute phase reaction, MBL increased |
Candida albicans recognition | by a C type lectin receptor (beta glucan recognized) |
NOD receptors | Peptidoglycan recognized |
NOD receptor location | macrophages, dendritic cells, epithelial cells |
Function of NOD | recognition of intracellular pathogens like listeria |
RIG I helicase receptor | nucleic acid of viruses recognized |
Function of RIG I helicase receptor | viruses recognized and IFN alpha & beta formed |
Effectors of innate immunity | Cellular: macrophages, dendritic cells, NKC (only for viruses) Non-cellular: complement, cytokines, proteins (APR), defensin |
Pro-inflammatory cytokines | Inflammosome, IL 1 |
Anti-inflammatory cytokines | IL 10, transforming growth factor beta (TGF beta) |
APRs : CRP MBL | CRP: binds to CHO in S. pneumoniae MBL: binds to mannan of bacteria |
Defensin | positively charged peptides; make pores and kill; antiviral too |
Defensin location | GIT intestinal crypts (neutrophils & paneth cells- alpha) lower respiratory tract (beta defensin) |
Alpha defensin | antiviral, doesn't let HIV bind to CXCR4 |
APOBEC3G (apolipoprotein B RNA editing enzyme) | against retrovirus, |
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