2. (a) What are the basic components of a flow cytometer? How can immunophenotyp
ID: 3517977 • Letter: 2
Question
2. (a) What are the basic components of a flow cytometer? How can immunophenotyping by flow cytometry be used in investigating suspected case of acute leukaemia? (5 marks) (b) A 48-year-old man has noticed a swelling in his left upper abdomen. On examination, he has an easily palpable spleen. There is no history of foreign travel, no jaundice and no drug history. He drinks alcohol occasionally, but there are no signs of chronic liver disease. A CBC shows the following ?? Plt 465x 10/L WBC 68.5 ×109/L 9.5 g/dL Myeloblasts Promvelocytes 190 Myelocytes Metamvelocytes 8% Bands Neutrophil Lymphocyte 10% Monocyte Eosinophil Basophil 15% 18% 37% 2% 3% 5% (i) What is the significance of the elevated WBC count and abnormal WBC differential count? What are the possible conditions that can give such abnormalities? (3 marks) (ii) The neutrophil alkaline phosphatase score (NAP) score is 2 for this patient, and 50 for a normal healthy subject. What is the principle of the cytochemical staining for demonstrating NAP? How is the NAP score obtained? How does the NAP score aid in the diagnosis? (5 marks) (iii) Justify the use of cytogenetic studies for this patient and predict the results. With the aid of a (4 marks) diagram, briefly describe the predicted cytogenetic abnormality Briefly describe the molecular mutation resulting from the cytogenetic abnormality. (1 mark) What is the usual treatment for this disorder? What is the mode of action of the drug? (2 marks) (iv) (v)Explanation / Answer
1). Flow cytometry is the measurement of characteristics of single cells suspended in a flowing saline stream. A basic flow cytometer consists of five main components:
- a source of light i.e. Laser
- a flow cell
- optical components to focus light of different colours on to the detectors.
- electronics to amplify and proces the resulting signals and
- a computer
Flow cytometer is a very useful tool and is used worldwide. It's importance in scientific research and diagnosis is increasing. It is now used routinely in many labs to detect the presence of specific surface and intercellular markers, measure metabolic activity and DNA content, among many other uses.
The use of flow cytometry provides an insight inti differential pathways, maturation stages and abnormal features of these population which are clinically relevant for the diagnosis of haematological malignancies. The presence amd absence of antigens or in the cells population, are recognised by various monoclonal antibodies (MAG) which gives characteristics immunostaining defining the cell lineages thus helping in making the diagnosis of leukaemia.
Flow cytometric immunophenotyping haa been incorporated in the diagnosis and further characterisation of active leukaemia in addition to morphological diagnosis.
2). Significance of elevated WBC count could mean an increased production of white blood cells to fight an infection.
A reaction to a drug that increases WBC production. A disease of bone marrow, causing abnormally high production of WBC cells.
An immune system disorder that increases WBC production
Some specific conditions of high WBC
- acute lymphocytic leukaemia
- chronic lymphocytic leukaemia
- tuberculosis
- whooping cough, etc.
Abnormal differential WBC count here shows decrease in neutrophils and lymphocytes
Conditions of decrease in neutrophils are:
Anemia
Bacterial infection
Chemotherapy
Influenza or other viral illness
Radiation exposure
Conditions of decrease in lymphocytes are:
Chemotherapy
HIV infection
Leukaemia
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