Haematology: Laboratory Investigation of White Cell Disorders Flashcards
What are the normal haemoglobin values for a male and female?
- Normal Male: 130 - 180g/L
- Normal Female: 120 – 160g/L
What is the normal white Cell (Blood) Count for an adult?
- Normal Adult: 4.0 - 11.0 x 109 / L
What is the normal Platelet Count for an adult?
- Normal Adult: 150 - 400 x 109 / L
What are the 5 major groups of white blood cells and what are the normal ranges of all of these cells within the blood?
- Neutrophils: Normal range 2.0 - 7.5 x 109/L
- Lymphocytes: Normal range 1.5 - 4.0 x 109/L
- Monocytes: Normal range 0.2 - 0.8 x 109/L
- Eosinphils: Normal range 0.04 - 0.4 x 109/L
- Basophils: Normal range < 0.01 - 0.1 x 109/L
Roughly what percentage of the white cell count is made up by neutrophils and lymphocytes?
- 90-95%
Basophils are the least abundant white cell within the blood so it’s very rare to see a raised basophil count, what is the most common cause of a raised basophil count?
- Haematological malignancy, e.g lymphoma or myeloma
What are some of the functions of Eosinophils?
- Protect against parasetic infection
- Play a role in allergic reactions
What is the name of the stain used on blood films?
- Romanowsky Stain
What are the main components of the Romanowsky Stain?
- Basic dye (Azure B or Methylene Blue) or Acidic dye (Eosin Y) with a buffer
- Buffer keeps pH of stain at 6.8
What are some characteristics of lymphocytes?
- Major role is in Adaptive Immune Response
- They Differentiate between self and non-self cells within the body
- Lymphocytes mainly protetc against viral attacks
Why might smeone have a low lymphocyte count (Lymphocytopenia) during a viral infection?
- Would expect to have a high lympocyte count during a viral infection as lymphocytes mainy protect against viral infections
- Lymphocytopenia may occur because viruses may suppress white cell production in bone marrow
What are the 3 major types of lymphocytes?
- T-cells
- B-cells
- Natural Killer (NK) cells
What are the functions of each of the types of lymphocytes?
- T-cells - Involved in Cell-Mediated Immunity, cytotoxity
- B-cells - Involved in humoral Immunity (antibody production)
- Natural killer cells - Can naturally attack virally infected cells and tumour cells without adaptive response - therefore they’re classified as part of innate immune response
What are the 2 different types of T-cell and what are their functions?
- T-helper cells (CD4+ cells) - Help the activity of other immune cells by releasing T cell cytokines
- Cytotoxic T-cells (CD8+ cells) - Kill tumour cells or virually infected cells that have antigens on their surface that the CD8+ cell is able to recognise as “non-self “ (Adaptive immunity)
Briefly describe the development of each of the different blood cells in the bone marrow
- Pluripotent haemopoietic stem cells in bone marrow can commit to becoming either a myeloid progenitor cell or a lymphoid progenitor cell
- Myeloid progenitor cells then commit to a specific lineage to become one of a vast number of granulated blood cells: Nuetrophils, monocytes, eosinophils or basophils
- They can also differentiate into megakaryocytes which become platelets
- They can also differentiate into erthroid cells which become the RBCs
- Lymphoid progenitor cels commit to a specific lineage to become one of the 3 types of lymphocyte: B lymphocyte; T lymphocyte or a natural killer cell
What is Leucocytosis?
- Increase in white cell count
What is Leucopenia?
- Decrease in white cell count
What is Neutrophilia?
- Increase in neutrophil count
- For normal bacterial infection neutrophil count doesn’t really go above 20 x 109/L
What does a neutrophil count above 20 x 109/L (severe neutrophilia) indicate?
- Usually indicates a haematological malignancy
- May also indicate severe sepsis or infection
What changes can occur to neutrophils during bacterial infection?
- Increased production from bone marrow (nuetrophilia)
- Toxic Granulation - Granules of neutrophil become more dark and coarse
- Shift to the left - More immature neutrophils (mainly band form neutrophils) are released into the blood stream and so their nucleus is more band-like and less segmented compared to a mature neutrophil
- Shift to the right - Increased release of hypersegemented (giant) neutrophils into blood stream
- Döhle Bodies - can also be formed
Briefly describe the formation of a neutrophil (myelod maturation)
What is the most common cause of hypersegemnted neutrophils?
- Vitamin B12/Folate deficiency
What are some of the causes of neutrophilia?
-
Physiological stress
- Post-operative
- Pregnancy
- Bacterial infection
- Inflammation e.g. vasculitis
- Carcinoma
- Steroids - Neutrophils have steroid receptor on cell surface
- Myeloproliferative disorders
- Treatment with myeloid growth factors
What is a leukemoid reaction?
- When an infection causes a massive increase in neutrophil count that mimics the increase seen as a result of leukaemia
How do you investigate neutrophilia?
- Conduct a full blood count (FBC) and differential white cell count
- Blood film examination
- Bacterial culture screen for infection - test blood/urine/saliva cultures for different types of bacteria
- Bone marrow examination and chromosome analysis (testing for presence of Philadelphia chromosome)
- Molecular analysis for BCR-ABL oncogene
- Last two tests for chronic myeloid leukaemia
Why was Chronic myeloid leukaemia (CML) historically a very important disease in medicine?
- It was the first disease discovered that was due to an acquired chromosomal translocation
- Chromosomal translocation between chromosomes 9 and 22 causes fusion chromosome (Philadelphia chromosome to form)
- As a result of this the BCR-ABL oncogene is also formed on the fusion chromosome
- It was the first disease where a targeted therapy on molecular level (imatinib) was used to treat it
What is neutropenia?
- Decrease in neutrophil count
What are some of the causes of neutropenia?
- Viral Infection
- Drug Induced e.g. sulphonamides
- Radiotherapy and chemotherapy
- May be due to ethnicity as afro-carribean and asian population have a slightly lower neutrophil count (benign ethnic neutropenia)
What are some causes of eosinophilla?
- Allergic diseases e.g. asthma
- Parasitic infections
- Drug sensitivity
- Myeloproliferative diseases e.g Chronic myeloid leukaemia or Hodgkin’s Lymphoma
How do you investigate eosinophilla?
- FBC and differential white cell count
- Blood film examination
- Stool examination for ova and parasites
- Check patients drug history
What is monocytosis?
- Increased monocyte count
What are some casues of monocytosis?
- Tuberculosis (TB)
- Acute and chronic monocytic and myelomonocytic leukaemia
- Malaria
How do you investigate monocytosis?
- FBC and differential white cell count
- Blood film examination:
- For abnormal white blood cells
- For malarial parasites
- Bone marrow examination - leukaemia
- TB cultures
What is lymphocytosis?
- Increased lymphocyte count
What are some causes of lymphocytosis?
-
Normal Physiological Status
- Lymphocytosis of childhood
- Bacterial Infection
-
Viral Infections
- Hepatitis
- Mumps
- Rubella
- Glandular Fever
- Lymphoid Leukaemias and lymphomas
How do you investigate lymphocytosis?
- FBC and differential white cell count
- Blood film examination
- Look for Atypical mononuclear cells
- Throat swabs/saliva/urine/blood samples to look for signs of viral infection
What are atypical mononuclear cells?
- Thye’re lymphocytes that have been transformed by an infection
What diseases are most likely to produce aytpical mononuclear cells?
- Glandular Fever (Infectious Mononucleosis)
How do you diagnose glandular fever (Infectious Mononucleosis)?
- Monospot/Paul Bunnell Test
- Infectious Mononucleosis Test
How do you distinguish if there’s an increased amount of B cells or T cells in the blood as a result of lymphocytosis?
- Immunophenotyping
- Flow cytometry
- T-cells express CD3,4 and 8
- B-cells express CD19 and 20
- B-cells demonstrate clonality by light chain restriction
- T-cells demonstrate clonality by T-cell Receptor Gene Rearrangement Studies
- NOTE: Clonality = malignancy
