micro unit 10B - antibodies + humoral defenses

development of immunological system, immunological disorders, tissue transplantation, allergic disorders (hypersensitivity), immunological tests

what cells are involved in making antibodies (humoral defenses)?

lymphocytes

what are the two types of lymphocytes

t cells and b cells

where are t cells produced?

in red bone marrow

where do t cells mature?

thymus, behind the sternum

t cells make up what % of total lymphocytes?

60%

b cells make up what % of total lymphocytes?

35%

after responding to Ags, t cells form what?

3 subsets of t cells (t helper cells, regulatory t cells, cytotoxic cells)

what do t cells secrete?

cytokines—chemical messengers

t helper cells (T_H; CD4 cells) activate b cells to make what?

Ab and macrophages

how do t helper cells make Ab and macrophages?

by activating b cells

regulatory t cells (suppressor, CD8 cells) suppress what?

other t cells

how do regulatory t cells work? why?

by turning off the function of other t cells because they are not needed to protect the immune system all the time

cytotoxic cells (T_C; CD8 cells) recognize and kill what cells?

target cells, non-self, hijacked, and tumor cells + transplanted foreign tissue

how do cytotoxic cells kill foreign things in the body?

apoptosis; cytotoxic cells must destroy our healthy cells to kill something harming the body within the cell

programmed cell death

apoptosis

cytokines

chemical messengers of the immune cells

“cytokines” are a general name; what are some other types?

interleukins, interferon, tumor necrosis factor

how many types of cytokines are there?

200+

cytokines are responsible for what?

attracting macrophages, protecting against viral infections, producing toxins to tumor cells, increasing Ab production

what cell attracts macrophages, protects against viral infections, produces toxins to tumor cells, and increases Ab production

cytokines

b cells make what?

antibodies

what produces b cells?

stem cells

where do b cells mature?

red bone marrow

why are they called “b cells?”

found in chickens’ lymphoid tissue in the bursa of fabricius

how do b cells work?

they carry old immunoglobulins on their surface (IgD or IgM)

when they recognize an Ag from the old immunoglobulin, the b cell is activated through the assistance of T_H cells to produce memory cells and plasma cells

what do b cells carry on their surface?

old immunoglobulins (IgD or IgM)

what happens when b cells recognize an Ag?

they become activated by t helper cells to produce memory and plasma cells

memory cells

cells that store information so that your body can more quickly build antibody when an antigen is reintroduced

plasma cells

cells that build the antibody when an antigen is reintroduced

what are the results of antigen-antibody binding?

1) when Ab encounters Ag it forms an Ag-Ab complex

2) Ab molecule is not damaging to Ag, but it triggers mechanisms that are damaging (3 mechanisms)

what are the antigen-antibody mechanisms?

agglutination, opsonization, neutralization, complement activation

agglutination

reduces # of microbes (clumping)

opsonization

sticky protein, opsonin, produced → enhances phagocytosis

neutralization

blocks viral attachment + neutralizes toxins (exotoxins + endotoxins)

complement activation

serum protein that causes inflammation + cell lysis

SCID is what type of immunodeficiency?

congenital

SCID

severe combined immunodeficiency (agammaglobulinemia); deficiency in both T and B cells, unable to produce Abs, treated by gene therapy

inability to produce Abs and treated by gene therapy

SCID

bruton’s disease is what type of immunodeficiency?

congenital

bruton’s disease

decrease in number of b cells → less Abs; more prone to infections

digeorge syndrome

defective thymus → less mature t cells; more prone to infections

digeorge sydrome is what type of immunodeficiency?

congenital

defective thymus → less mature t cells, more prone to infections

digeorge syndrome

decrease in number of b cells → less Ab, more prone to infections

bruton’s disease

autoimmune diseases

Ab against “self”

how many types of autoimmune diseases?

80+ (75% in women)

rheumatoid arthritis (RA)

anti-gammaglobulin Abs

systemic lupus erythematosus (SLE)

anti-DNA Abs

what are the other autoimmune diseases

scleroderma, psoriasis, chron’s disease, multiple sclerosis

what is the common treatment for autoimmune diseases?

immunnosuppresants → compromise the patient’s immune system

AIDS

acquired immunodeficiency syndrome

what happens in the immune system of a patient with AIDS?

1) HIV attaches to CD4 receptors on T_H cells → decreases the number of T_H cells

2) decreased amount of Abs due to decreased t helper cells despite b cells being normal, but not activated

autograph

self-graft

isograft

grafts between identical twins

xenograft + heterograft

graft between different species

homograft + allograft

graft between members of the same species

histocompatibility

graft acceptance or rejection dependent on human leukocyte antigen (HLA)

is an anaphylactic reaction immediate or delayed?

immediate

is an anaphylactic reaction antibody-mediated or cell-mediated?

antibody-mediated

is a cytotoxic reaction immediate or delayed?

immediate

is a cytotoxic reaction antibody-mediated or cell-mediated?

antibody-mediated

is an immune complex reaction immediate or delayed?

immediate

is an immune complex reaction antibody-mediated or cell-mediated?

antibody-mediated

is a delayed type reaction antibody-mediated or cell-mediated?

cell-mediated

what are examples of things that cause an anaphylactic reaction?

insect stings, drugs or food allergies, hay fever, allergic asthma

what is the interval for an anaphylactic reaction?

2-30 minutes

sensitizing dose

1st exposure to allergen → not always indicative that you will have an anaphylactic reaction in the future

what happens in the sensitizing dose of an anaphylactic reaction?

body produces IgE → FAB recognizes allergen and FC attaches to basophils or mast cells

what happens in the shocking dose of an anaphylactic reaction?

basophils or mast cells increase histamine → increase in gastric, lacrimal, and nasal secretions → vascular permeability increases → blood pressure drops which can result in anaphylactic shock → localized anaphylaxis may occur (hives, itchy, reddening skin, throat closing)

shocking dose

2nd exposure to allergen

what is the treatment an anaphylactic reaction?

anti-histamine or epinepherine; constricts blood vessels + increases blood pressure

what tests determine the allergen in an anaphylactic reaction?

skin tests, eosinophilia, IgE (RAST)

what are examples of things that cause cytotoxic reactions?

transfusion blood reactions (WRONG BLOOD), hemolytic diseases of the newborn (HDN)

what is the interval for a cytotoxic reaction?

5-12 hours

what happens in a cytotoxic reaction?

body exposed to Ag + attach to target cells (rbc, wbc, platelets); complement activated + cytolysis occurs

what are examples of things that cause an immune complex reaction?

strep throat → post-streptococcal glomerulonephritis + rheumatic fever

what is the interval for an immune complex reaction?

3-8 hours

what happens in an immune complex reaction?

body exposed to Ag → body makes IgG or IgM → Ab binds with Ag to form Ab-Ag immune complex

immune complex is very large, deposited on blood vessel walls and penetrate walls to cause inflammation

sequelae infection

secondary consequence, NOT secondary infection

what are examples of things that cause a delayed type hypersensitivity reaction?

TB tine skin test, some drug allergies, poison ivy

what is the interval for delayed type hypersensitivity reaction?

2-3 days (delay due to time for t cells + macrophages to migrate to Ag)

is there Ab involvement in a delayed type hypersensitivity reaction?

no Ab involvement; caused by t cells

what happens in a delayed type hypersensitivity reaction?

Ag enters body + attaches to target tissue → t cells activated + react with Ag to destroy Ag but also destroys target tissue in the process, known as dermatitis

direct immunological test

looking directly for the antigen (i.e. strep)

indirect immunological test

detection of Ab (i.e. HIV)

what is the specimen for direct testing?

specimens will vary

what is the specimen for indirect testing?

serum