Biommunology

Fyll på detta "review" papper genom att redigera inlägget. Tack för alla som medverkat.

Questions

1. What does the expression immunity mean? Explain acquired immunity-vaccination and serum treatment.

Immunity is a “memory” preventing you from being sick (sometimes it is lifelong and sometimes not). It is something you “gain” after a sickness (the antibodies produced to fight it back that time will float around in your systems, patrolling, and when they encounter a new attack of similar virus/bacteria they will response swiftly), or by vaccination. Vaccination (or serum treatment, as it also is called??) can either give you a passive immunity or an active one. The same goes for the immunity you gain through other means (such as breast milk) – it can either be passive or active. An active immunity is one where your own cells are actually producing the antibodies (that usually gives you a “memory” that lasts), while a passive immunity is just some antibodies produced somewhere else that are injected into you. Even though it will help you for the moment you still risk being sick again, as soon as all the given cells are dead.

2. Describe the immune response when attacked by bacteria.

Macrophages catch the bacteria and start chewing it, dividing it into smaller pieces and using those to send a signal (antingen), through the MHC ll, to the T-helpers. T-helpers react by starting to divide and activating the B-cells. B-cells start to divide as well, producing plasma cells filled with antibodies. The antibodies are very specific and they go out there and kill those bitches (the bacteria).

3. What happens when one is attacked by virus?

As we all know by now viruses are much smaller than bacteria and they are, unlike bacteria, not just floating around there easy for everyone to find and kill, but they hide in our own cells and reproduce. That makes it pretty much impossible for the antibodies and the macrophages to take care of them on their own, they need some professional help: the T-killers. The T-killers job is (after the microphages managed to detect an intruder and send the signal on to the T-helpers which send it on to the T-killers) to go to all the cells of the body, one by one, and check if they are infected or not. The MHC l, a small “flag” each of our cells have that is unique for every person, gives the T-killers the required information. If a cell is infected the T-killer will get rid of it: make it burst, so that the antibodies can kill the viruses infecting it.

4. Describe the immune response when infected by a parasite.

The eusinophiles (granulocytes) will attack the parasite with their powerful enzymes.

IgE antibodies are produced on the Mastcells inte the intestines and mucus. IgE cover the mastcell and the antigen (protein from parasite) will attach. There are vessels on the mastcell with histamine which will be released when the surface is filled at the IgE complex.

Histamine can cause diarrhea, thinner blood and vessel swelling.

5. Explain the allergic reaction. What do we mean with the expression hypersensitivity? Can allergies be treated?

An allergic reaction is when the immune defense attacks ordinary/common and non-dangerous substances in your body, an excessive immune response or hypersensitivity. What happens is that the antigens from one of these sources bind with the mast cells and are then attacked by antibodies, which in turn causes the mast cells to produce potent chemical substances such as histamine. Histamine is responsible for the obnoxious symptoms.

You can treat the symptoms by giving anti-histamine drugs.

6. What are monoclonal antibodies and how are they produced?

Monoclonal antibodies are identical antibodies produced from cloned hybridoma cells. Theses cells are produced by fusing tumour cells with antibody-secreting cells. These new cells, hybridoma, have combined the property of tumours, continous division, with the secretion of antibodies.

7. How can your body defend you from cancer?

The transformed cells of tumours express antigens that are not found on normal cells. To the immune system, these antigens appear foreign, and their presence causes immune cells to attack the transformed tumour cells.

The main response of the immune system to tumours is to destroy the abnormal cells using killer T cells, sometimes with the assistance of helper T cells. Tumour antigens are presented on MHC1 molecules in a similar way to viral antigens. This allows killer T cells to recognize the tumour cell as abnormal. But some tumours evade the immune system and go on to become cancers.

Macrophages identify a cancer cell. When fusing with the cancer cell, the macrophages will inject toxins that kill the tumour cell.

8. Describe the meaning of autoimmunity.

Autoimmunity is when the immune system reacts on your own cells (too effective defense so to speak). This renders many of your own cells dead and there will be tissue with inflammation, like swollen blood vessels due to active macrophages. B-Cells react with Ig’s (antibodies) and T-Cells with MHC1 (protein structure on own cells)

Examples:

Juvenil diabetes: Pancreas give insulin. The Ig’s attach to the insulin receptor which is a protein structure, which will not let the insulin to get to its right place.

Myastena gravis: Ig's attach to the receptors of muscles allowing it no contact with the nerves. The result: the muscle is destroyed.

SLE (systematic lupus erythematosus): Ig's attach to the proteins in the body-liquids (such as DNS structures, left-overs from the dead cells) and make them stuck in the joins

Reumatic arthritis (=ledgångsreumatism): Inflamation in joints (DOES ANYONE KNOW THE DIFFERENCE BETWEEN SLE, REUMATIC ARTIBRITIS AND MS?)

MS (multiple sclerosis): Ig's attacking mglin in neves

9. Why is HIV so devastating? Use gp120 and CD4 in your explanation.

HIV is a small virus consisting of RNA genes surrounded by a protein coat. The RNA codes for its own specific proteins, one of which is an enzyme called reverse transcriptase. The DNA copy is spliced into the gene of the infected human. This causes a persistent infection and making the host cell become a factory for HIV replication. One of the virus proteins that the DNA codes for (in the viral coat) is called gp120. This is vital in targeting the virus to cells of the immune system which thus become infected and damaged.

People with AIDS have a greatly reduced number of T helper lymphocytes. The Human Immunodeficiency Virus (HIV) is invading the T-Helper cells which is in turn causing the immune system to fail, thus other infections are easily caught. The T helpers are catacterised bu a molecule on their surface membrane called CD4 which is central to communication between cells of the immune system.

The viral gp120 molecule has a region that binds to a part of the lymphocyte, allowing the viral RNA to enter the cell.

The CD4 interactions with the macrophages are at the very heart of cell-mediated immunity. Thus people with AIDS have several defects in their immune system, with reduction in the number and functioning of their CD4 lymphocytes.

10. Describe the immune problems around transplantation surgery.

The main problem is the rejection of donated organs. Special treatment is needed to suppress the patient’s immune system. The body destroys the foreign tissue as it would treat bacteria or virus. Grafts between identical twins will have the same genes and are therefore perfectly matched compared to regular donations. The matching of blood groups is essential just as the tissue typing of the white blood cells.

There is drug treatment to prevent rejection, drugs which keep the lymphocytes from attacking the graft. Too much of the suppressing medicine may have negative effects too, making the risk of getting an infection high.

Important terms

Anaphylactic chock is: protein in your blood which drops the blood pressure and makes the blood thinner.

Histamine is a biogenic amine involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. It is found in virtually all animal body cells. New evidence also indicates that histamine plays an important role in chemo taxis of white blood cells. (Wikipedia)

Autoimmunity (React on your own cells, perhaps because of too effective defence)

is the failure of an organism to recognize its own constituent parts as self, which results in an immune response against its own cells and tissues. Any disease that results from such an aberrant immune response is termed an autoimmune disease. (Wikipedia)

- T-Cells react on MHC1 (protein structure on own cells)

Monoclonal antibodies

- T-cells with CD8 connect to cells and kill foreign cells

- P53 comes to the surface of the enemy so that T-Cells can kill them

T-Cells

Stem cells give leucocytes which give T-lymphocytes which are T-Cells. They are a part of the adaptive defence. Responsible for the cell-mediated immunity.

- Principal organ in its development: Thymus (brass). They get educated there.

- Look like B-Lymphocytes but do not produce antibodies.

T-Cells are expert on specific attacks. They need signs, substances, from the target which they get from other cells that break the targets down. The matching antigen is shown to the special receptors on their surface and the production of the specific type starts. Some of the become memory cells which will stay in the body for several years. This allows the defence to be quicker once the same specific attack from the bacteria or virus launches again.

- T-Helpers à told by IgM to go to war. They help the other cells in the immune system. Stimulate B-Lymphocytes to divide into antibody producing cells.

- T-Killers à kill the attacking force. They destroy body cells infected with viruses before the viruses have time to proliferate. The can also attack cells from other individuals if they get into the body – causes rejection problems.

- T-Suppressors à IgG gets them to act. Suppress other cells in the immune system, serve as a break so that the system does not over-react.

B-lymphocytes

B=bone marrow derived. Consists of different, specific clones.
When it encounters an antigen it starts to divide and produce antibodies. A micro-organism can have several different types of antigens=it will activate several different clones.