Immunology Flashcards
Four Classes of Pathogens
- Viruses
- Bacteria
- Fungi
- Protozoans and Worms
Immunogen
Molecule than can induce an immune response Foreign (not a shared self molecule) Large (>10 Kda), complex molecule Biodegradable (not inert) Can be allergens, microorganisms, etc.
Antigen
Molecule that can be recognized by immune system components
Immunogens and haptens
Innate vs. Adaptive Immunity
Innate- initial response to immunogen; epithelial barriers, phagocytes, dendritic cells, complement system, and NK cells; non specific and no memory
Adaptive Immunity- more specific with memory and turns on after innate; B cells to make Ab, T cells to effector T cells (CD8/cytotoxic cells that kill specifically, CD4 are directors of immune response for immune system to be more effective)
Neutrophil
phagocytosis and activation of bactericidal mechanisms
in circulation
Eosinophil
killing of Ab-coated parasites
in circulation
Basophil
promotion of allergic responses and augmentation of anti-parasitic immunity
in circulation
NK Cell
releases lytic granules that kill virus infected cells
in circulation
Monocytes
immature form of macrophages
in circulation
Lymphocytes
cells of adaptive immunity B and T cells B cells produce Ab T cells exert cytotoxic or regulatory functions in circulation
Macrophage
phagocytosis and activation of bactericidal mechanisms, antigen presentation, and wound healing
located in the tissues
Macrophage are pro-inflammatory and dedicated to destroying the bacteria
Once the infection is killed you must remove the neutrophils, so the macrophages then clean up the area
Produce factor to attract fibroblasts to secrete ECM to regeneration of tissue can occur
Inflammation – vessels become more leaky
produce IL-1 and TNF alpha to adhere leukocytes to endothelium as well as increase number of ICAM proteins on endothelium
Dendritic Cells
antigen uptake in peripheral sites
antigen presentation
in the tissues
Mast Cells
release of granules containing histamine and active agents
in tissues
Present near blood vessels and beneath surfaces exposed to the external environment.
They can release preformed inflammatory mediators from cytoplasmic granules, such as histamine.
In addition, they can start synthesizing inflammatory compounds such as such as prostaglandin D2, leukotriene C4, growth factors and chemokines
Upon interaction with its receptors, histamine can induce vasodilation favoring leukocyte infiltration to the tissues
Primary Lymphoid Organs
Thymus and Bone Marrow
where cells are produced
Secondary Lymphoid Organs
Adnoids, tonsils, lymph nodes, appendix, spleen, Peyer’s patches in ileum
Where cells go
Acute Inflammation: Macroscopic vs. Histologically
Macroscopic appearance (clinical manifestation) is defined by the presence of redness, heat, swelling, pain and loss of function. Histologically, it is defined as the presence of edema fluid and the infiltration of tissues by leukocytes
Characteristics of Acute Inflammation
It lasts from minutes to a few days after the infection is sensed and is characterized by:
- local environment changes
- microvasculature activation
- leukocyte accumulation (mostly neutrophils)
Pathogen Recognition Receptors
Immune cells carry “pathogen recognition receptors” (PRRs) that detect molecules shared by various microbes.
These microbial molecules are named “pathogen associated molecular patterns” or PAMPS.
Examples of PAMPS are lipopolysaccharide present in gram negative bacteria; double stranded RNA generated by viral replication; or flagellin, a constituent of bacterial flagella
PRRs such as toll-like receptors (TLRs) interact with PAMPS and induce immune responses; TLRs are located on the plasma membrane or endosome membrane
Upon contact with their ligand, signaling events ensue in the cells
IL-1beta
activates vascular endothelium, lymphocytes, local tissue destruction, and increases access of effector cells
TNF alpha
activates vascular endothelium and increases vascular permeability, which leads to increased entry of IgG, complement, and cells to tissues and increased fluid drainage to lymph nodes
IL-6
lymphocyte activation and increased Ab production
CXCL8
chemotactic factor recruits neutrophils, basophils, and T cells to site of infection
also called IL-8
IL-12
activated NK cells
induces differentiation of CD4 T cells into TH1 cells
Extravasation
The body must undergo changes locally through vasodilation and increased vascular permeability in the area of the agent inciting the inflammatory reaction to allow white blood cells to accumulate
The white blood cells must then leave the blood vessel, cross the basement membrane, and be drawn to the area where they are needed. This process is called extravasation
The process by which white blood cells are drawn to the area where they are needed is referred to as chemotaxis
Increased permeability of capillaries as a result of histamine, kinins, and prostaglandins allows PMNs to migrate through the capillary wall to reach the bacteria. This migration is called diapedesis and takes several minutes to occur.
