Infection and Immunity Wk 8 - Lesson 61

What is the vascular change in chronic inflammation?

neovascularization

What are the systemic changes in chronic inflammation?

low grade fever, weight loss, anemia

Which inflammation is fibrin present?

acute

Which inflammation is fibrosis present?

chronic

How long does chronic inflammation last?

days to months

What are the roles of macrophages?

phagocytosis/digest dead cells, antigen presentation, secrete cytokines

What is the reticuloendothelial system or macrophage system?

term for macrophages being permanent residents of some tissues

Why does a granuloma form?

body is having difficulty getting rid of the pathogen or material and is resorting to confining it

What cell causes a granuloma?

macrophages wall off pathogens

What are the chronic exudates?

granulomatous and lymphoplasmacytic

What is granulomatous caused by?

fungi, parasites, mycobacteria, foreign body, others

What cells are involved in granulomatous exudate?

predominantly macrophages with fewer lymphocytes and plasma cells

What is granulomatous vs granulomas?

granuloma is a type of granulomatous inflammation

What happens over time with granulomatous exudate?

becomes encapsulated with fibrous connective tissue and often has a necrotic center

What is the gross appearance of granulomatous exudate?

not much of a fluid component because little vascular response; causes the tissue to be enlarged or raised, firm, and pale

What is the benefit of granulomatous inflammation?

robust mechanism to eliminate or sequester an inciting cause; initiation of antigen presentation to include adaptive immunity

What is the cost of granulomatous inflammation?

infiltration of immune cells impedes organ function; not a good sign; the body's beginning to concede that containment may be the best option

What is the resolution for granulomatous inflammation?

inciting cause may be eliminated or if containment unsuccessful, the inflammatory process starts again

What is the function of T-lymphocytes?

host cell killing

What type of immunity is T-lymphocytes?

cell-mediated immunity

What is the function of B-lymphocytes?

antibody production

What type of immunity is B-lymphocytes?

humoral immunity

How does T-lymphocytes cause cell killing?

make contact with infected cell and release cytotoxins that results in a protease cascade within the cell (apoptosis)

What cells are involved in lymphoplasmacytic exudate?

infiltration of lymphocytes and plasma cells because they respond to the same response

What can cause lymphoplasmacytic exudate?

associated with viruses, hypersensitivities/immune mediated conditions, toxins, and other intracellular processes

What is the gross appearance of lymphoplasmacytic exudate?

tissue appears pale and flat with no fluid component

What type of necrosis is hard to differentiate from lymphoplasmacytic exudate?

coagulative

What is the benefit of lymphoplawsmacytic inflammation?

inclusion of host cell killing and antibody-mediated immunity in the inflammatory response

What is the cost of lymphoplasmacytic inflammation?

inflammatory infiltrates often contribute to organ dysfunction

What is the resolution for lymphoplasmacytic inflammation?

will resolve if inciting cause eliminated

What is an antigen?

foreign molecular structure that can initiate an adaptive immune response

What are examples of antigens?

microbial molecules, toxins, abnormal molecules expressed on surface of tumor cells

What are examples of antigen presenting cells?

dendritic cells, macrophages, B-cells, any nucleated host cell that is infected or a tumor cell

What is the function of MHC molecules?

enable presenting cells to present antigenic peptide fragments to T-lymphocytes

What is the function of the B-lymphocytes?

make antibody when becomes a plasma cell, a semi-pro APC

What are the essential elements of the adaptive immune system?

antigen, antigen presenting cell, MHC molecule, B and T cells

What depends if something is an antigen or not?

the environment in which the antigen is in

What can antigens do?

inducing an adaptive immune response and interact with the products of the response

What does the antigen interact with?

specific antibody, specific T-cell receptor, specific B-cell receptor, MHC molecules

What are properties of a good immunogen?

molecular size, complexity/chemical composition, stability, foreignness

What make the best antigens?

foreign proteins

What size does a good immunogen need to be?

needs to be >1000 Daltons (1kDa) to be immunogenic

What composition do good immunogens need to be?

complex molecules

What molecules are poor immunogens based on chemical composition?

carbohydrates, plastics, lipids, and nucleic acids

What molecules are good immunogens based on chemical composition?

proteins and glycoproteins

What is a poor immunogen based on stability?

plastics

What is the importance of foreignness with good immunogens?

it prevents the immune system from responding to self-antigens and only responding to foreign molecules

What is an epitope?

portion of the immunogenic molecule that binds the antibody, BCR, and TCR

How many epitopes does an immunogenic molecule contain?

several different epitopes and each epitope will be recognized by different antibody, BCR, or TCR

How are protein epitopes confirmational?

immune responses are dependent on recognizing the proteins in their native or conformation state

What happens when the protein is denatured or degraded?

immunogenicity may be lost

Which type of epitope will lose immunogenicity with denaturing?

confirmational epitope

What are haptens?

small molecules that cannot elicit an immune response in an animal (in vivo)

When can hapten molecules by seen by the adaptive immune system?

when they bind a larger molecule or cell in the animal

What immune response happens with haptens?

humoral immune response

When can antibodies bind to haptens?

When haptens are bound to a larger molecule or once an antibody is generated for that hapten, the antibody can bind to free haptens

What is an example of a hapten?

penicillin

What happens when penicillin binds to RBCs?

The immune system can see the penicillin and produces antibodies against it which will result in the destruction of the RBCs; drug-induced hemolytic anemia

What are examples of haptens?

drugs, hormones, toxins

What can penicillin result in?

Type-1 hypersensitivity to penicillin (allergy)

What are two mechanisms for lysing RBCs coated with antibody?

complement activation via the classical pathway, host cells expressing receptors for the Fc part of antibody (phagocytic cells and NK cells)

What is cross-reacting antibodies?

identical or similar epitopes are sometimes found on apparently unrelated molecules

What is the result of cross-reacting antibodies?

antibodies generated against an epitope on one antigen may react with an unrelated antigen

What is the example with cross-reacting antibodies and Brucella abortus?

B. abortus (important bacteria) and some strains of Y. enterocolitica (unimportant bacteria) share some epitopes; Yersinia exposed cow may be wrongly thought to have been exposed to B. abortus

What is an example of cross-reacting antibodies with autoimmune conditions?

some microbial epitopes are similar to the animal's own tissue epitopes; immune response to the microbial epitopes may trigger generation of antibodies that attack the animal's own tissue

What is an example of cross-reacting antibodies with RBC blood types?

people with "A" RBCs will have anti-B antibodies in their serum when they have never been exposed to "B" antigen; natural antibodies

What are natural antibodies?

antibodies against foreign antigens without any know previous infection, vaccination, transfusion exposure to account for it

Where do natural antibodies arise from?

exposure to antigens on harmless bacterial or food that are identical or similar to other epitopes

How are RBCs and bacteria identical?

possess cell-wall glycoproteins with carbohydrate side-chains

What are the most important microbial antigens?

protein molecules

What other molecules from microbes can also be immunogenic?

carbohydrates and lipids

What are good immunogens from bacteria?

bacterial pili, flagella, and cell wall proteins

What is a good immunogen for viruses?

glycoproteins

What are some non-microbial antigens?

allergens, cell surface proteins such as: RBC glycoproteins, MHC molecules, CD molecules

What are MHC molecules required for?

antigen presentation to T-lymphocytes

How are MHC molecules important in transplantation medicine?

a recipient can generate an adaptive immune response to foreign MHC molecules expressed by donor organ/tissue which causes rejection of the donor organ

What are cluster of differentiation molecules?

naming system for surface molecules (antigens) on normal immune cells; each CD molecule denotes a protein with a specific function

What cells express CD3?

all mature T-lymphocytes

What cells express CD4?

all mature T-helper cells

What cells express CD8?

all mature CTLs express