Intro to Immune Flashcards
a. Humoral immunity
i. Mediated by proteins called antibodies which are produced by cells called B lymphocytes
ii. Cannot gain access to microbes that live and divide inside infected cells
1. Complement, acute-phase proteins, and natural Abs which are generated against Ags derived from normal gastrointestinal microflora rather than being produced in response to an infection.
2. Ex: C-reactive protein
3. Opsonization with CRP promotes the uptake of cells by phagocytes
b. Cell-mediated immunity
i. Mediated by T lymphocytes
ii. Activate phagocytes to destroy microbes that have been ingested by the phagocytes into intracellular vesicles
1. Multiple cell types that use a set of specific receptors to recognize and remove pathogens and cellular debris
2. Neutrophils, monocytes, and macrophages are Phagocytes
3. Mast cells, basophils, and eosinophils are essential components host defenses against multiple parasites and allergies
4. Natural Killer (NK) cells play a key role in the elimination of infected and malignant cells, cause destruction by apoptotic mechanisms
Natural Immunity
i. Person is exposed to a live pathogen, develops an infection, recovers from the disease, and becomes immune
ii. Takes several weeks to develop, but provides a long lasting protection
Artificial (Active) immunity
i. Exposure to killed or attenuated pathogenic microorganisms without contracting an infection
ii. Provides a long lasting protection but takes several weeks to obtain
iii. Used only for prophylactics of infectious diseases
Passive Immunity
i. Patient is given someone else’s Abs as a therapeutic treatment of the ongoing infection
ii. Short lived, but helps protect right away
Hypersensitivity
i. Result of specific memory is that re-exposure to the same stimulus as well as or instead of eliminating the stimulus, has unpleasant or damaging effects on the body’s own tissues
Autoimmune Disease
i. Stimulating a response to the body’s own structures
ii. Attacked as if they are foreign
Immune Deficiency
i. Absence of one or more elements of the immune system
ii. Can be congenital or acquired after birth
+G-CSF
Myeloblast→basophils, eosinophils, neutrophils (granulocytes)
+M-CSF
Monoblast→Monocytes, Dendritic cells
T cell Key Markers
CD3, CD4, CD8
B cell Key Markers
CD19, CD20
NK Cell Key Markers
CD56
Macrophage/Monocyte Markers
CD14
Phagocytes
i. Neutrophils and macrophages
ii. Ingest and destroy microbes
iii. Steps in response
1. Recruitment of cells to the sites of infection
2. Recognition of and activation by microbes
3. Ingestion of the microbes
4. Destruction of ingested microbes
iv. Secrete cytokines which promote and regulate immune responses
Dendritic Cells
- Originate from monocytes or from IFN
- Langerhans cells residing in epidermis of the skin is a subset
vi. Tissue-resident macrophages are long-lived cells derived from a transient hematopoietic progenitors emerging in the yolk sac
vi. Mast cells and basophils both contain
- Histamine, serotonin, heparin
- cytokines and chemokines
- basophilic purple granules
acute inflammation
o Tumor (swelling) o Rubor (redness) o Calor (heat) o Dolor (pain) o Function laesa (loss of function)
What can induce a fever?
TNF, IL-1, IL-6
PAMPs
- Indicators of the presence of particular pathogens
- Unique to particular classes of pathogens
- Cannot be altered, suppressed, or hidden from the surface
- No structural similarity with self Ags
- Ex: Porins, Lipoproteins, Liposaccharides, Lipoteichoic acid, teichoic acid, mannoproteins, beta-glycan, lipoarabinomannan
IFN alpha/beta
o Block viral replication within host cells
o Induce expression of proteins that interfere with virus replication
o Activates nuclease ribonuclease L which then mediates viral RNA degradation
o Activate NK cells to enhance cytotoxicity
Natural killer cells
o Kill virus-infected cells
o Ability is inversely related to expression of MHC class 1 on the target cells
o Recognize ligands on infected cells or cells undergoing other types of stress
o Secrete IFN-gamma so macrophages kill phagocytized microbes
Pneumococci microbial evasion
Polysaccharide inhibits phagocytosis
Staphylococci microbial evasion
production of catalase, breakdown of reactive oxygen
Neisseria meningitidis microbial evasion
sialic acid expression inhibits C3 and C5 convertases
Streptococci microbial evasion
blocks binding of C3 to organism and C3b to receptor
Pseudomonas
Synthesis of modified LPS that resists peptide antibiotics
