Lab Investigations of White Cell Disorders Flashcards
What is a Haemocytometer Neubauer Chamber used for?
Haemocytometer Neubauer Chamber was used to count cells in the past
How is a Haemocytometer Neubauer Chamber used to count no. of cells?
Put blood film on cover glass mounting support and count
Would count no. of squares and multiply it out to get cell no.
What is the modern day technique for counting WBCs?
Nowadays more automation techniques are used e.g. ADVIA
How do modern methods distinguish between cells?
Results obtained are complicated dot plots distinguishing samples based on size and granules
What blood cells are we able to identify nowadays?
We identify:
- Haemoglobin
- White cell
- Platelets
- Neutrophils count
Describe the normal Hb levels expected of a FBC
Haemoglobin (Hb)
Normal Male: 130 - 180 g/L
Normal Female 120 – 160 g/L (lower due to menstruation)
What is the purpose of a full blood count?
need to know normal values to compare to
Once we’ve obtained abnormal Hb results from FBC how can we identify the problem?
Once we’ve identified Hb value we differentiate using MCV (micro/macrocytic)
What is a normal WBC count?
Normal Adult 4.0 - 11.0 x 109 / L
Outline a normal platelet count of an adult
Platelet Count Normal Adult 150 - 400 x 109 / L (Plt)
How many types of WBCs are there?
There are the 5 major groups of WBCs - their subtotals should add up to total WBC count
Outline the normal ranges of the 5 major WBCs
> Normal Range x 109 / L Adult
Neutrophils 3.5 x 109 / L 2.0 - 7.5 (most abundant) Lymphocytes 1.7 x 109 / L 1.5 - 4.0 Monocytes 0.3 x 109 / L 0.2 - 0.8 Eosinophils 0.2 x 109 / L 0.04 - 0.4 Basophils 0.0 x 109 / L <0.01 - 0.1
What is the significance of neutrophils?
Neutrophils are very important in bacterial infections → belong to myeloid pathway
What is neutrophilia?
Neutrophilia - high neutrophil count
What is neutropenia?
Neutropenia - low neutrophil count
What is a high neutrophilia indicative of?
A higher neutrophilia is most likely a haematological cancer not bacterial infection
What is the significance of lymphocytes?
Lymphocytes are next most common WBC and they belong to lymphoid pathway (mostly raised in viral infection)
What is lymphocytosis?
Lymphocytosis - high lymphocyte count
What is lymphocytopenia?
Lymphocytopenia - low lymphocyte count
Which WBCs would we not expect a high frequency?
Monocytes, eosinophils and basophils are minority populations in the blood.
What does a high basophil count tell us?
Basophils are rarely seen in the blood, so high no.’s indicate a problem (most commonly haematological malignancy) - nothing to do with infections
Describe the significance of eosinophils
Eosinophils important in parasitic infections - test stool sample to confirm
When is the eosinophil count elevated?
Also important in allergic reactions (ie. skin rash, asthma etc.) increase eosinophil count
Also elevated in some autoimmune diseases
What is the significance of monocytes?
Monocytes involved in TB and raised in haematological malignancies
How is a blood film observed in the lab?
blood film seen using light microscope
What can we see from a WBC blood film?
Looking at the tail end we can identify different cell populations
Describe the normal arrangement of neutrophils on a blood film
Have 3-5 lobes and granules
Larger than RBCs
Cytoplasm appears pinkier toned
How can we find out if a RBC is regularly sized just by looking at a blood film?
To identify a regular RBC size, compare to lymphocytes (neutrophils are larger than lymphocytes)
Outline normal morphology of lymphocytes on a blood film
Similar size to RBC, and contain hardly any cytoplasm (bluer) mostly occupied by large, dense nucleus - no granules
Describe the difference between T and B lymphocytes on a blood film
Can’t distinguish between T or B lymphocytes from a blood film
What is the main role of lymphocytes?
Major role is in Adaptive Immune Response
How do lymphocytes respond to viral attack?
Differentiation between self and non-self e.g. Viral attack
- B Lymphocytes produce antibodies to destroy that
specific virus
- Memory cells
What are the 3 types of lymphocytes?
T-cells
B-cells
Natural Killer (NK) cells
What is the role of T cells?
T-cells are involved in Cell-Mediated Immunity (eat up cells)
What are the common types of T cells?
CD4+ T-Helper cells
CD8+ Cytotoxic T-cells
What is the role of B cells?
B-cells in Humoral Immunity i.e. Antibody Production
What is the role of NK cells?
Natural Killer cells are part of the Innate Immune System attacking virally infected cells and tumour cells without developing specific cell mediated response
Describe the morphology of a large granular lymphocyte
Granular but unlike neutrophils has only one lobe
Cytoplasm is paler
What is the morphology of monocytes on a blood film?
Biggest cells in a blood film (almost 3x size of RBCs)
Dumbbell shaped nucleus
Bilobed vacuoles also present
How do we differentiate between eosinophils and basophils on a blood film?
Eosinophils are very similar to neutrophils
But eosinophil granules are a lot denser and orange in colour - looks as though its ready to degranulate (allergic response)
Describe basophil morphology on a blood film
Thicker, darker granules that hide the nucleus
Very distinctive
Where are blood cells formed?
Bone marrow produces all blood cells
Describe the haematopoietic pathway WBCs belong to
Most WBCs belong to the myeloid progenitor pathway
Which cells belong to the lymphoid pathway?
Lymphoid pathway produces T lymphs , B lymphs and NK cells
What is leukocytosis?
Leukocytosis: Increase in white cells
What is leukocytopenia?
Leucopenia: Decrease in white cells
How do toxic granulation cells appear on a blood film?
Granules are no longer hazy, they are darker and denser (similar to basophil) - basophils are still much thicker
Why are toxic granulation cells less developed?
Nucleus is less developed (less lobed) as hasn’t had the time to form correct lobed structure as body responding to stress quickly
When does myeloid maturation occur?
Shift to the LEFT in neutrophil development
Starts with blast cells in bone marrow - should not be seen on blood film - indicative of leukaemia
What causes a hypersegmented neutrophil to be present on blood film?
shift to the RIGHT
9-12 lobes commonly due to B12 / folate deficiency
What are dohle bodies?
Toxic granulations form a prominent single rod shaped dohle body - not v. common
When is neutrophilia expected to occur?
Normal Physiological Reaction
Post-operative
Pregnancy
What are the pathological causes o
- Bacterial Infection
- Inflammation e.g. vasculitis
- myocardial infarction
- Carcinoma
- Steroid treatment - v. common
neutrophils have steroid receptors - Myeloproliferative disorders
- Treatment with myeloid growth factors
How do we investigate neutrophilia?
- FBC and differential white cell count
- Blood film examination
- Bacterial culture screen for infection
- Bone marrow examination + chromosome analysis
How can we investigate neutrophilia using FBC?
- if all cells affected = bone marrow issue
- RBC = anaemia /iron
- White cells = leukaemia / infections
How is a bacterial culture screen taken in neutrophilia patients?
collect samples to test for bacteria:
- Urine sample
- Blood sample
- Sputum sample
- Skin swab
What is the purpose of a bone marrow exam and chromosomal analysis?
Testing for (CML) chronic myeloid leukaemia
Philadelphia chromosome: translocation between chromosomes 9 and 22
Molecular analysis for BCR-ABL oncogene
What form of white cell disorder is acute myeloid leukaemia?
Acute myeloid leukaemia is increased blast cells not mature neutrophilia
What causes neutropenia?
Viral Infection
Drug Induced e.g. sulphonamides
Radiotherapy and chemotherapy (predictable)
Part of a pancytopenia in bone marrow failure (aplastic anaemia) or infiltration e.g. leukaemia
What is a non-pathological cause of neutropenia?
Racial: ‘benign ethnic neutropenia’ - in afro caribbean and asian populations lower neutrophil count - exclusion diagnosis (last resort)
What causes eosinophilia?
- Allergic diseases e.g. asthma, hay fever
- Parasitic infections
- Drug sensitivity
- Myeloproliferative diseases e.g CML
- Hodgkin’s Lymphoma
How can we investigate eosinophilia?
- FBC and differential white cell count
- Blood film examination
- Stool examination for ova and parasites
What are the causes of monocytosis?
Tuberculosis (TB)
Acute and chronic monocytic and myelomonocytic leukaemia
Malaria
Outline the investigation of monocytosis
- FBC and differential white cell count
- Blood film examination:
- for abnormal white blood cells
- for malarial parasites
- Bone marrow examination - leukaemia
- TB cultures
When is lymphocytosis a normaloccurence
Normal Physiological Status in childhood (1-6 years)
Normal: 5.5 – 8.5 x 109/L
How does lymphocytosis appear on a blood film?
Lymphocyte no. almost equates RBC no. = lymphocytosis
What are the pathological causes of lymphocytosis?
Bacterial Infection Viral Infections e.g. - Hepatitis - Mumps - Rubella - Pertussis - Glandular Fever - (Infectious Mononucleosis)
What malignancies is lymphocytosis indicative of?
Leukaemia
Lymphoma
Which cells become tumorogenic in lymphocytosis?
acute lymphoid leukaemia = blast cells
chronic lymphoid leukaemia = normal lymphocytes
Where do lymphocytes originate?
Lymphomas originate from lymph glands
How do we investigate lymphocytosis?
- FBC and differential white cell count
- Blood film examination
- Atypical mononuclear cells
- ?Glandular Fever caused by EBV
(Infectious Mononucleosis; Kissing Disease) - Monospot, Paul Bunnell Test, Clearview
- Infectious Mononucleosis Test
Describe morphology of atypical mononuclear cells
Big = blasts or monocytes
V. pale cytoplasm
Scalloping - seen to just border RBCs
What type of cells are atypical mononuclear cells?
Resemble monocytes to some extent but actually are lymphocytes that have been transformed due to infection
What pathological condition shows atypical mononuclear cells?
V. common in infectious mononucleosis or glandular fever
What are heterophile antibodies?
Heterophile antibodies are antibodies which react against an antigen which is completely unrelated to the antigen which originally stimulated it
Give an example of heterophile antibodies?
Human antibodies reacting against sheep or horse or bovine cells
What is chronic lymphocytic leukaemia?
cancer of bone marrow lymphoid cells
Which malignancies are mature lymphocytes present in
Chronic lymphocytic leukaemia
Lymphoma
When is immunophenotyping used to investigate lymphocytosis?
Immunophenotyping to determine if lymphocytes are:
B-cells:
- Demonstrate clonality by light chain restriction
T-cells:
- Demonstrate clonality by T-cell Receptor Gene Rearrangement Studies
What cytokines are secreted by T cells?
T cells always express CD3, 4 & 8
Which cytokines do B cells release?
B cells express CD 19 & 20