Practical Three: Immunology

 

 

Layout of samples and controls on ELISA plate

  1 2 3 4 5 6 7 8 9 10 11 12
A Tube1 Tube2 Tube3 Tube4 Tube5 Tube6 Tube7 Tube8 Tube9 Ser1 Ser2 Ser3
B Tube1 Tube2 Tube3 Tube4 Tube5 Tube6 Tube7 Tube8 Tube9 Ser1 Ser2 Ser3
C Neg Pos                    
D Neg Pos                    
E                        
F                        
G                        
H                        

Key: Ser= Serum sample, Neg= negative sample and Pos= Positive sample

 

Assuming the readings obtained at 405 nm in the plate reader as below:

 

  1 2 3 4 5 6 7 8 9 10 11 12
A  2.804  2.07  1.405 0.835  0.583 0.329  0.222  0.205 0.19  1.751  0.540  0.914
B  2.737  2.111  1.509  0.904  0.555  0.33  0.233  0.194  0.171  1.809  0.524  0.866
C  0.140  1.090                    
D  0.141  1.029                    

 

Answer the following questions

 

  1. Use the results to plot a graph of absorbance against positive control (standard) concentration on the next page (or on other graph paper if you wish). The top concentration in the positive control A1 is 50 ng/L CEA (remember you added 250 μl of 100 ng/L standard to 250 μl PBS). Make sure you label your axis appropriately, use correct units where applicable and have an appropriate descriptive legend beneath the graph. (6 marks)

Paste your graph here-

  1. What is the antigen in this experiment? (1 mark)

 

 

 

 

 

 

  1. What did the results from the controls show? (2 marks)

 

Positive-

 

 

 

Negative-

 

 

 

 

  1. Assuming the top standard contains a final concentration of 50 ng/L CEA calculate the concentration of antigen in the serum samples. (3 marks)

SAMPLE 1: ___________________

 

SAMPLE 2: ___________________

 

SAMPLE 3: ___________________

 

Comments: The normal reference range for CEA is 2.5 ng/L to 5 ng/L

 

  1. State whether serum samples 1-3 were normal or abnormal (1.5 marks)

 

 

2.

 

3.

 

 

 

 

 

  1. What is the biological function of CEA? (1 mark)

 

 

 

 

 

  1. Why measure CEA levels prior to and after surgery? (2 marks)

 

 

 

 

 

 

 

 

 

 

  1. Cancer biomarkers can sometimes produce false positives. Other than human error what could cause a false positive to occur in a CEA test? (2 marks)

 

 

  1. Does high CEA level always indicate cancer? Justify your answer. (1.5 marks)

 

  1. Based on the reports from the three practicals and haematology results (see Practical one- case study brief) what would be your diagnosis for the patient? Justify your answer. (4 marks)

 

 

 

 

Overall:                            / 70

 

Overall:                            %

 

 

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