SCRIED (1420) Semester 2, 2014 Part B: Short Answer Questions (6 marks each): Se
ID: 126183 • Letter: S
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SCRIED (1420) Semester 2, 2014 Part B: Short Answer Questions (6 marks each): Select 5 out of the 8 questions plete your answers in the answer booklet provided; suggested length 3-5 sentences Question S1 Explain the differences in the types ifferences in the types of antigens recognised by B cells and T cells, answer a comparison of the antigen receptors used in each case, Question s2 mmune mechanisms that would be involved in acute rejection of a Explain the treatments are currently used to avoid allograft rejection. (Question S3 Explain the difference between congenital and acquired immunodeficiency disease - give an example of each type of disease. Question S4 Describe the key features of a dendritic cell that make it an especially effective antigen presenting cell, include in your answer the signals that a dendritic cell would provide to activate a naïve T cell. ( Question S5 A man cuts his foot on a piece of rusty metal which is contaminated with bacteria. Describe the innate immune mechanisms that will help defend him against infectior by these pathogens. Question S6 A developing T cell must undergo both positive selection and negative selection before it can reach maturity. Explain what is involved in each of these processes and where in the thymus each process occurs.Explanation / Answer
1.The antigen recognition molecules of Bcells are the immunoglobulins or Ig.THese proteins are producedby Bcells in a vast range of antigen specificities,each bcell producing immunoglobulin or the Bcell surface serves as a cells receptor for antigen and is known as Bcell receptor.The antigen recognition molecules of Tcells are made solely as membrane bound proteins and only function to Tcells for activation.These Tcell receptors are related to immunoglobulins both in their protein structure having v and c regions.
2.It can occur less than three months i.e early acute rejection or after three months.While rejection episodes and delayed graft function increases the renal allograft loss,strong immunosupressive therapies reduce the frequency of acute rejection.Antibody mediated rejection is responsible for acute rejection.Antibodies cause acute graft abnormalities that are distinct from tcell mediated rejection.
3.Acquired disease: It is a condition that is not genetically predetermined.It can be gotten just after birth or for the rest of the life by external factors.AIDS is causede by the HIV virus for which it is transmitted mostly by external factors like sexual contact,blood transfusions,syringe pricks etc.
congenital:It is a condition in which it develops from genetics.At different stages of fetal development the fetus may or may not be sensitive or at risk or abnormalities and disabilities such as congenital heart and other organ disorders.
4.Dendritic cells are antigen presenting cells of the mammalian immune system.THeir main funtion is to process antigen material and present it on the cell surface of the Tcells of the immune system.THey act as messengers between the innate and the adaptive immune systems.
5.Innate immunity is activated by the recognition of a set of molecules that are found only on invading substances rather than on cells of the body.Any sign of things such as bacterial lipopolysacharide,double stranded RNA and bacterial flagellin will trigger an inflammatory reponse.The chemical messengers released once the invading pathogen has been sighted includes hiatamine,prostaglandins etc.
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