Immunity

Ab's (Immunoglobulins) - Structure

-is a Y-shaped molecule that is flexible due to hinge area - may assume a T-shape to accommodate different sized antigens -Ab monomer's have 4 polypeptide chains - 2 heavy and 2 light -chains are linked by disulfide bonds -the Constant Portion (the arm part of the Y shape) have the same amino acid sequence seen in all monomers of a given class

igE

0.002% of Ab's in serum - found attached to mast cells and basofils (two cells involved in allergic responses reactions)they are involved in allergic response reactions (stimulates histamines) (stimulates them to release histamines) histamines make us miserable, itchy scratchy eyes/nose, so we take otc meds

igD

0.2% of Ab's in serum - don't quite know what it does they just know that its different, but they know that they find it in blood and lymph fluid and on the surface of B cells

Two components of the Immune System

1. Humoral Immune System 2. Cell Mediated Immune System (CMI)

igA

10-15% of antibodies in serum (but by far most common antibody in mucus membranes and body secretions so most abundant antibody in the body) example, tears, saliva, breastmilk, mucus - igA is the most common one in body as a whole - can be found as a single molecule (Y shaped one) or a dimer >--^--< in mucus secreations mostly are dimers. It coats the surface of pathogens and helps to prevent them to attach to host tissues.

Colostrum

1st breast milk (1st 24 hours after birth) high in antibody's and high in protein = temporary immunity

igM

5-10% of Ab's in serum. (M for macro because they are large molecules.) they form pentamers five of them they are to big to leave the bloodstream like igG - 1st antibody to show up after an infection - g clumps them together so phagocytes can eat them, 2nd to show up igG to get there - not able to cross placental barrier - it also enhances phagocytic cells (makes them more aggressive)

Immunoglobulin class G - igG

80% of Ab's in serum - small molecule, can leave blood vessels and enter tissue fluids (cross barriers) - primary antibody that crosses the placental barrier functions: protect against bacterial and viruses in blood stream - neutralization bacterial toxins - enhances phagocytic cells (makes them more aggressive)

Ab=Antibody=immunoglobulin=Ig

An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens.

acquired immunity

Another aspect of the body's defenses. It involves production of a specifific defensive response when the host is invaded by foreign substances.

Acquired Immunity: natural or artificial, active or passive (we didn't always have - in utero or after birth

Refers to immunity that develops in response to exposure to a microbe or other invaders

Ag=Antigen

anything that is foreign to the body and that elicits (causes) an immune response example - virus and bacteria - dust and pollen - transplanted tissue

suppressor T cells - Ts

believed to shut down the immune response when the battle has been won, these cells tell them to stop - because if they didn't stop then the person will get an auto immune disease - so the suppressor T cells prevent auto immune disease

placental transfer

cross placenta barrier to get temporary immunity, anything that the Mom is immune to the new baby is also immune to

T-cells - 4 types

cytotoxic t cells - target and destroy antigen upon contact and they help protect against the following cancerous cells, transplanted tissues (they play role in rejection process) they protect against intracellular bacteria and viruses, they also help against the helminths (mutli cellular - tapeworms and such.)

Naturally acquired active immunity

develops in response to exposure to antigens in our day to day lives

Artificially Acquired active Immunity

from vaccination with bacterial toxins (inactivated), killed bug or attenuated (heated) microbes

Monomer Class refers to

ig group, igG, igA, etc. 5 classes - igG - Immunoglobulin class G or just say IGG igM - igA - igD - igE -

Hummoral Immune System

involves Antibodies dissolved in blood plasma and lymph (the bodies "humors") - which are produced by B-cells lymphocytes after they are exposed to an antigen.

Cell Mediated Immune System (CMI)

involves specialized lymphocytes called T-cells that are located in the blood and lymph, they don't produce antibodies but do have antibody like molecules called antigen receptors on their surfaces (4 different types of T-cells)

Naturally qcquired passive immunity

natural transfer of Antibody's from immunized donor to nonimmunized recipient; like a pregnant Mom --> fetus across placenta = placental transfer or from Colostrum - 1st breast milk

Artificially acquired Passive Immunity

occurs upon injection of antibodies obtained from outside source; example- snake bite - anti-venom produced in horses then harvest blood from the horse serum or plasma and then inject into a person

Antigens or Immunogen - (Ag) foreign to the body

stimulates the body to produce Ab's and/or sensitized T-cells Some possible antigens include -proteins -nucleoprotein (nucleic acid and protein) -large polysaccharides -May be a component of invader: o pili o capsule o toxins o viral coat Some Non-microbial Ag's include: o pollen o egg white o tissue transplant o blood from another person

Serum

the clear fluid which remains after blood cells and clotted material are removed. it still contain most of the Ab's. For this reason fluid containg Ab's is called antiserum. Serum contains different components which can be separated by electrophoresis -Alpha -Beta -Gamma - the majority of Abs are found dissolved in this fraction of serum -Albumin (imagine a vile of blood after it's separated, the bottom 2/3 area is the clotted blood and the top 1/3 area is the serum)

helper T cells - Th

they perform a function called antigen presentation. they grab ahold of the antigen and bring it to the B cell and tell them to deal with it, they deliver the antigen to the B cell, thats what causes B cells to go thru that other process (b cell --> plasma --> Ab)

delayed hypersensitivity T-cells - Td

they play a role in the inflamation reaction - example - if you had a skin test for TB it would cause swelling and react on the site (it is called delayed because it takes a while for them to get there)

stem cells

very controversial, their source is controversial, interesting because stem cells can become anything they want to be, they just need a stimulus to tell them what to be, they are embryonic (needed further developement) some of them migrate to the thymus and when they are done they become mature Stem cells,

B cell - a lymphocyte (where do antibodies come from?)

when B cells are exposed to antigens they undergo some further development and they become plasma cells - these plasma cells produce and secrete the antibody molecules