Samester 2 204 Part Three- Long Answer Questions (10 marks each): Select 3 out o

Question

Samester 2 204 Part Three- Long Answer Questions (10 marks each): Select 3 out of the 5 questions.t lete your answers in the Answer Sooklet provided, suggested length: up to 1 page Question L1 nfluenza wrus infects epithelial cells lining the airway. Describe in detail the events woud need to occur in order to generate an effective adaptive immune response to eliminate this virus Question L2 The gut has·complex unwanted immune gut environment that could be used to treat conditions such as allergy or arrangement of immune features that normally prevents responses against food proteins. Explain the key features of the promote tolerance. Give an example of how this mechanism autoimmunity. Question L3 The first postulate of Bumet's clonal selection theory states that: Each ymphocyte bears a single type of receptor with a unique specificity. Briefly describe the processes involved in the generation of unique immunoglobulin receptors Expliain how an antibody response to a pathogen. Bumet's clonal selection theory applies to the induction of the innate and adaptive immune systems. Include in your answer a comparison oferelativesf ths and weaknesses of the two compartments, how the cells from each compartment recognize and become activated by pathogens, and comment on the diversity of the antigen receptors used in each pool. Question L5 Explain how cancer cells can escape effective anti-tumour immunity and describe the strategies used by the immune system to overcome these mechanisms. Include in your answer a short descrption of an immunotherapy approach that is designed to improve an ur our immune responses. END OF EXAMINATION

Explanation / Answer

Immunity: Resistance of body against the pathogenic agents is known as immunity.It is the ability of the body to resist all types of foreign bodies like bacteria,virus,toxic substances,etc..which enter the body.

The immune systems depends on two main types: 1. Innate or General defense

2. Adaptive or Specialized defense

against specific pathogen ---- adaptive -- Defence -- innate ---- against foreign bodies,injuries and pathogens

Stengths and weakness of innate immune system:

1. It is able to take action very quickly. It makes sure, for example that bacteria that have entered the skin through a small wound are detected and partly destroyed on the spot within few hours.

2. Complement system: Proteins in a chain reaction --- Soluble substances support the defense cells of the innate immune system.

3.The natural killer cells: Searching for changed body cells - They are the third important part of the innate immune system. They specialize in identifying cells that are infected by a virus or that have become tumorous.

4. Protection from the outside: Skin and mucous membranes -- All external and internal surfaces of the human body are a key element of the innate immune system. The closed surface of the skin and of all mucous membranes already forms a mechanical barrier for pathogens, which prevents them from entering.

5. Protection from the inside: Defense cells and proteins.

Inspite of all obstacles, pathogens make it past the skin or mucous membranes and enter the body, the innate system’s second line of defense comes into action. Inflammatory cells move to the site of infection, or defense cells that are already there are activated. Soluble protein substances of the complement system (see below) are activated, too, and help to defend the body. This leads to an inflammatory reaction where blood circulation is increased and the affected area becomes swollen and hot. Sometimes there is also a fever.

6. It is not specialized for specific action, it doesnt need a long time. Because of this wide effect, it is only capable to a certain degree of stopping germs from entering and spreading into the body.

Stengths and weakness of adaptive immune system:

1. If the body’s first line of defense – the innate immune system – is unsuccessful in destroying the pathogens, after about four to seven days the specific adaptive immune response sets in. This means that the adaptive defense takes longer, but it targets the pathogen more accurately.

2. It can remember the aggressor and acts specifically against certain antigens. If there is new contact with an antigen that is already known, the defense response can then be quicker.

This way the defense responses of the adaptive immune system are more efficient and faster than those of the innate defense, if the antigen is already known.

3. The adaptive immune system can remember the antigens because it produces memory cells.

4. The adaptive immune system has several parts that react in different ways, depending on the place in the body where the pathogen is.

Antigens: The antigens are the substances which include specific reactions in the body. Antigens are of two types : 1. Those present on the body's own cells are called the autoantigens or self antigens.

2. The antigens on the non self cells -- are known as nonself antigens or foreign antigens.

Nonself antigens:

1.The receptors on the cell membrane of microbial organisms such as bacteria,viruses and fungi.

2. The toxins from microbial organisms.

3. The material from transplanted organs or incompatable blood cells.

4. Allergens or allergic substances like pollen grains.

Chemical nature of the antigens:

The antigens are mostly the conjugated proteins like lipoproteins, glycoproteins and nucleoproteins.

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