Abnormal white cell count Flashcards
What is meant by pancytopenia
All blood cell lineages reduced
What is meant by haemopoiesis
Haemopoiesis: production of blood cells in Marrow
Creation of mature blood cells
Describe normal haemopoiesis
Normal haemopoiesis (polyclonal healthy/ reactive)
Normal marrow
Reactive marrow - very active bone marrow- in response to infection or inflammation for example.
Describe malignant haemopoiesis
Malignant haemopoiesis (abnormal/clonal) Leukaemia (lymphoid,myeloid), myelodysplasia, myeloproliferative
Malignant- cancer cells divide from mother cells- same features as mother cells- clonality- fundamental feature of cancer- helps distinguish process from a benign condition
Outline the cell lines that the haemopoietic stem cells can differentiate into
HSCs -- Pre T- T cell HSC- Pre- B- B cell HSC- Meg-CFC- Megakaryocyte/platelet HSC- GM-CFC- Granulocytes and Monocytes HSC- BFU-E- RBCs
§ HSCs can differentiate into many cell lines.
o BFU-E = Blast Forming Unit Erythrocyte.
What are the granulocytes
Granulocytes (neutrophils, basophils and eosinophils)
Describe the key properties of haemopoietic stem cells
Capacity for self-renewal
Multi-potent
Which cells come under the myeloid cells
Erythrocytes Neutrophils Basophils Eosinophils Monocytes Macrophages Megakaryocytes Dendritic Cells
What is the lymphoid lineage
Lymphoid cells are lymphocytes = T cells, B cells and NK cells
What is important to remember about the differentiation and maturation of blood cell lineages
Different stages of maturation- normally exclusively seen in the bone marrow
Normal- should only see mature cells in the peripheral blood
Describe two circumstances in which we may see immature cells in the peripheral blood
GCSF – growth hormone (daily injection in cancer patients to recover neutrophils after chemotherapy)
Following single injection- will see lots of different myeloid precursors
Sepsis- bone marrow tries to compensate for stressful situation- releases lots of myeloid precursors- typically immature white cells and nucleated red cells- presence together- leucoerythroblastic picture- important to recognise- indicates patient is septic or that the bone marrow is infiltrated by a tumour
Outline the normal steps of differentiation to a mature neutrophil
myeloblast > promyelocyte > myelocyte > metamyelocyte (> neutrophil)
First 4 steps occur in the bone marrow
Hence only mature neutrophils should be seen in the peripheral blood.
Describe how the appearance of white cells changes as they develop.
They become smaller and their cytoplasm becomes clearer.
Will also develop a multi-lobed nucleus.
Describe the chemicals that influence differentiation and proliferation
Cytokines influence differentiation and proliferation
o RBCs – EPO.
o Lymphoid cells – IL-2.
o Myeloid cells – G-CSF, M-CSF.
What can affect these regulating cytokine signals
DNA directed differentiation and proliferation
§ DNA damage in cancer can affect these regulating signals and lead to the cancer proliferation.
o Leukaemia – malignant process in primary lymphoid organs.
o Lymphoma/Leukaemia – lymphatic cell tumours in tissue/blood.
o Myeloma – disease of bone marrow.
What can be given to patients with renal impairment to help manage the anaemia
Renal impairment- defective EPO- can treat with recombinant EPO- which improves the anaemia
Describe the two main groups of white cells and their overall function
White cells consist of two main groups:
Phagocytes; including monocytes and granulocytes, the subtypes of the latter including neutrophils basophils and eosinophils
Immunocytes; which consist of T and B lymphocytes. These cell types will react in response to different stimuli.
Both cell groups are present throughout body tissues and play a central role in the response to infection mediated via phagocytosis and soluble proteins of the immunoglobulin and complement system.
What do cells of the lymphoid lineage differentiate from
Lymphoblasts
What do the phagocytic cells differentiate from
Myeloid lineages
Myeloblasts
Promyelocytes
Myelocytes
Metamyelocytes
What is the key difference between the lymphoid tissue and peripheral blood
Lymphoid tissue vs peripheral blood: only mature cells in blood, mix of immature and mature cells in tissue
Broadly speaking, what two things can result in a leucocytosis
Increased white blood cell production
Increased white blood cell survival
Describe how an increased white blood cell production can lead to a leucocytosis
Reactive (essentially, a normal physiological response)
Infection (sepsis)
Inflammation
Malignant
Leukaemia
myeloproliferative
Clone of abnormal cells- acquired mutation that allows them to proliferate uncontrollably – malignant
What is the difference in the type of white blood cell seen in the peripheral blood of someone with an infection/inflammation (reactive) and someone with a malignancy (primary)?
Reactive – only mature white blood cells (to respond to the infection or inflammation)
Primary – mature AND immature white blood cells present
Describe how increased cell survival can cause a leucocytosis
Failure of apoptosis (eg acquired cancer causing mutations in some lymphomas
Mutations in onco-suppressor genes- allows the cells to proliferate uncontrollably
Broadly speaking, what two things can result in a leucoocytopenia
Decreased white blood cell production
Decreased White blood cell survival
Describe how a decreased white blood cell production can lead to a leucocytopenia
Impaired BM function B12 or Folate deficiency BM failure Aplastic anaemia Post chemotherapy Metastatic cancer Haematological cancer
Where is B12 of folate deficiency particualry common
Vegans
Can generally result in a pancytopenia
Describe how a decreased cell survival can lead to a leukocytopenia
Immune breakdown
Auto-antibodies against immune cells- many connective tissue disorders- but also in Autoimmune diseases.
Describe a reactive eosinophilia
Inflammation
Infection (usually parasitic- but any infection can increase eosinophil count)
Increased cytokine production (pan-neoplastic effect of some tumours):
-Distant tumour
-Haemopoietic or non haemopoietic
Eosinophils will retain normal morphology
Usually associated with other white cell abnormalities- monocytosis and neutrophilia
Rarely associated with symptoms
Describe pan-neoplasms that can cause a reactive esopinophilia
Important to investigate
Isolated tumours and hemopoietic cancers- Hodgking’s lymphoma
Release cytokines which trigger eosinophil production and proliferation.
Describe primary (malignant) eosinophilia
AbnormalHaemopoiesis (autonomous cell growth) Cancers of haemopoietic cells Leukaemia: -Myeloid or lymphoid -Chronic or acute
Myeloproliferative disorders
All myeloproliferative disorders- characterised by eosinophilia
Where does the mutation occur in CML and describe the consequences of this mutation
Mutation at early stage of haematopoiesis- instead of apoptosis- increased proliferation of cells in granulocytic lineage and platelets and monocytes
Very high white cell count
Blood film- will show every stage of white cell maturation
Summarise the first stages in investigating a leucocytosis
History and examination
Haemoglobin and platelet count
Automated differential (% and absolute number of each WC type)
Examine blood film
Describe why examination and history are so important
History- want to see if patient is symptomatic or not- leucocytosis can sometimes be a incidenta finding- patient asymptomatic- smoking- mild leuckocytosis in general population- common to see reactive lymphocytosis or neutrophilia
Ask for recent travel history- eosinophilia- knowing patient been in African area with G.I symptoms- indicated parasitic infection
On examination- focus on lymphadenothy and hepatosplenomegaly- underying lymho- or myeloprolierative disorder
Describe why it is important to look at Hb and platelet counts
Look at what happens to Hb and platelets
Isolated neutrophilia less concerning than combination with low Hb and raised white cell count
Mild neutrophilia- which is long-lasting and not associated with symptoms- likely to be reactive
Rarely with a patient with a low Hb, thrombocytopenia and raised WBC count- not something to be worried about- usually typical presentation of leukaemia
Describe the importance of the automated differential
If you get no differential- machine cannot recognise what the cells are- GCSF injection (myeloid precursors which the machine cannot characterise) or presence of malignant condition
When an elevated WBC is identified it is necessary to first look at the automated differential. Is the leucocytosis due to an elevation of a particular cell type i.e. an increase in one cell type only e.g. a lymphocytosis, a neutrophilia or an eosinophilia, or alternatively an increase in all cell types.
Summarise the other key stages in investigating a leucocytosis
Abnormality White cells only, or all 3 lineages (red cells/platelets/white cells) ?
White cells 1 cell type only, or all lineages? (e.g. neuts/eos/monocytes/lymphocytes)
Mature cells only or mature and immature cells?
Describe the importance of checking whether the abnormality is white blood cells only or all blood cell lineages
Can tell you what the disease is caused by
Raised WBC, raised HB and platelet count- myeloproliferative disorder
Malignant- only one type of white cell lineage increased – cancer is a clonal process- mother cell generated lots of daughter cells which are identical to the mother cell
Thus the abnormality of one particular cells
Chronic Lymphocytic Leukaemia - increased number of lymphocytes- but rarely any increase in myeloid cell lines
Describe the importance of checking whether the abnormality is in one white cell lineage only or others (myeloid/lymphoid)
Reactive- all types involved- one exception- CML- patients can have increase in all white cells- lots of white cells- of all different myeloid precursors- eosinophils, basophils (otherwise rarely seen in blood), to be sure of CML > AML –look for presence of eosinophilia.
Can tell you more about cause (reactive or malignant)
Describe the usefulness in checking whether the cells are mature cells only, or a mixture of mature and immature
Mature or immature- doens’t do much in distinguishing reactive from malignant- in CLL- all mature cells but malignant but in CML- both mature and immature cells.
Describe the potential causes of a leucocytosis where only mature cells are present
Lymphocytes
Reactive(viral) or primary
(chronic lymphocytic leukaemia
All lineages
or only one
neuts, eos, baso– reactive/infection
Describe the potential causes of a leucocytosis where only immature cells are present
Blasts +
low Hb
low platelets
? Acute leukaemia
Describe the potential causes of a leucocytosis where a mixture of mature and immature cells are present
Neutrophils+ myelocytes+ basophils ?Chronic myeloid leukaemia
What are the normal ranges of the different parameters
a. Hb 120-160 g/L b. Platelets 150-400 x 109/L c. WCC 4-11 x 109/L d. Neutrophils 2.5-7.5 x 109/L e. Lymphocytes 1.5-3.5 x 109/L f. Monocytes 0.2-0.8 x 109/L g. Eosinophils 0.04-0.44 x 109/L h. Basophils 0.01-0.1 x 109/L
What can an abnormal WCC be due to
§ Abnormal WCC can be caused by:
o Phagocytes – neutrophils, eosinophils and monocytes.
o Immune cells – lymphocytes (infection or CML).
Describe the key features of neutrophils
Present in BM, blood and tissues
Life span 2-3 days in tissues (hours in PB)
50% circulating neutrophils are marginated (not counted in FBC)
What is the difference between the circulating pool and marginated pool of neutrophils
Some neutrophils represent circulating pool- but others are margianted (adhere to endothelial cells and migrate into different tissues)
Balance between circulating and marginated pool- can change in minutes- stress- need more neutrophils- marginated pool can be switched into circulating- so neutrophilia can be developed in minutes
Outline the time frames in which neutrophilia can develop
§ Neutrophilia can develop in:
o Minutes – demargination.
o Hours – early release from BM – i.e. sepsis.
o Days – increased production – i.e. x3 in infection.
Describe the features of neutrophils in the peripheral blood when caused by infection
Neutrophilia >7.5x109/l
toxic granulation
vacuoles
Infection- abnormal neutrophils- white spots in cytoplasm (vacuoles)- abnormal distribution of granules-
Neutrophils in leukaemia do not have granules and do not look toxic.
Describe the features of neutrophils in the peripheral blood when caused by leukaemia
Chronic leukaemia
Chronic myeloid leukaemia
Neutrophilia and
Precursor cells (myelocytes
CML- lose different stages of myeloid differentiation
Band cells- neutrophils with non-segmented nuclei.
What else would be present in the blood film of someone with leukaemia that would not be present in someone with an infection?
Myelocytes and metamyelocytes – these precursors would not be found in the peripheral blood of someone responding to infection
What are the different causes of neutrophilia
Infection
Tissue inflammation (e.g.colitis, pancreatitis)
Physical stress, adrenaline, corticosteroids
underlying neoplasia
Malignant neutrophilia
myeloproliferative disorders
CML
Which infections may result in a neutrophilia
Localised and systemic infections
acute bacterial, fungal, certain viral infections
Which infections will not produce a neutrophilia
Some infections characteristically do not produce a neutrophilia e.g. brucella, typhoid, many viral infections.
Describe the causes of a reactive eosinophilia
1 Reactive
Parasitic infestation
Allergic diseases e.g. asthma, rheumatoid, polyarteritis,pulmonary eosinophilia.
Neoplasms, esp. Hodgkin’s, T-cell NHL- may make IL-5
Hypereosinophilic syndrome- heart damage- >1.5 – need to treat patients to prevent organ damage- regardless of underlying cause
Drugs also an important cause
Hodgkin’s disease will show up on x-ray with increased mediastinal mass and there will be increased IL-5 secretion (stimulates reactive).
You can also get a mutation in GM-CFC.
Malignancy- leucoerythroblastic picture- abnormal granules
Describe a cause of a malignant eosinophilia
Malignant Chronic Eosinophilic Leukaemia (PDGFR fusion gene)
mutation in alpha or beta gene
very rare
Describe monocytosis
Rare but seen in certain chronic infections and primary haematological disorders TB, brucella, typhoid Viral; CMV, varicella zoster Sarcoidosis Chronic myelomonocytic leukaemia (MDS)
Summarise the different causes of neutropholia
Bacterial - infection
Auto-immune
Tissue necrosis — inflammation
All types of neoplasia (cells not part of malignant population)
Summarise the different causes of an eosinophilia
parasitic- infection
Allergic
(asthma, atopy, drug reactions)- inflammation
Hodgkin’s
NHL– neoplasia (cells not part of malignant population)
What is an infectious cause of a basophilia
Pox virus
What is an infectious cause of mono
Chronic (TB,
Brucella)
Summarise the different causes of lymphocytosis
Mature or immature cells
If mature is it :
reactive to infection
primary disorder (CLL)
If immature it is: primary disorder (leukaemia/lymphoma)
Compare different blood films in lymphocytosis
LEFT picture:
o Cells are like each other – oligoclonal expansion.
o Could be CLL (Chronic Lymphocytic Leukaemia) or autoimmune conditions.
RIGHT picture:
o Immature lymphoblasts are much larger and you can see a nucleolus which shows immaturity.
o This is acute lymphoblastic leukaemia.
nuclei will be pinker
When we see mature cells in a lymphocytosis how can we easily distinguish between reactive and primary causes
Is it primary or reactive ?
Secondary (reactive); polyclonal response to infection, chronic inflammation, or underlying malignancy.
Primary; monoclonal lymphoid proliferation e.g. CLL
What will be seen in mononucleosis syndrome
“atypical lymphocyte”
Mononucleosis syndrome
Night time sweating, fatigue
Leukaemia- other lineages affectesd
nucleosis- not much change in other lineages
Describe the key features of glandular fever
Shows a reactive-looking lymphocyte that looks like an immature lymphocyte seen in acute lymphoblastic leukaemia BUT these lymphocytes tend to have RBCs clump them and they are jagged and are not self-clumped.
High WCC with reactive-looking lymphocytes shows glandular fever.
Describe the pathogenesis of glandular fever
EBV infection of B-lymphocytes via CD21 receptor
Infected B-cell proliferates and expresses EBV associated antigens
Cytotoxic T-lymphocyte response
acute infection resolved resulting in lifelong sub-clinical infection.
Cytokines from t-cells result in symtpoms
Describe lymphocytosis in elderly patients
Elderly patients with lymphocytosis mature lymphocytes (may be smear cells) differential: reactive to underlying auto immune disorder or chronic lymphocytic leukaemia
How can you distinguish?
Morphology
Immunophenotype
Gene re-arragement
Describe how we can evaluate lymphocytosis using (B cell) light chain restriction
Polyclonal expansion – involve more than one mother cell and so the light chains express both kappa and lambda.
o This is indicative of a response to infection.
Monoclonal expansion – all antibodies are from ONE mother cell and this is indicative of a cancer
Describe how we can evaluate lymphocytosis using gene rearrangement
Imuunoglobulin genes (Ig) and T cell receptor (TCR) genes undergo recombination in antigen stimulated B cells or T cells.
With primary monoclonal proliferation all daughter cells carry identical configuration of Ig, or TCR gene. This can be detected by Southern Blot analysis
What should we do when looking at an abnormal white cell count
Look at all aspects of FBC
Look at automated differential
Look at blood film
Likely causes of eosinophila in patient with recent travel history
Parasitic infestation (schistosomiasis) Underlying lymphoma (HL or T NHL) allergic autoimmune disorder (asthma/urticaria)
Describe case 2
Cells are mature – nucleoli cannot be seen.
Cells are very like each other – monoclonal expansion.
o Could be reactive – viral or TB.
o Primary/monoclonal – CLL.
Further tests show there is light chain restriction (kappa restriction) so this is most likely CLL.
Lymphoma- need lymph node biopsy- BM and blood normal
Peripheral blood immunophenotype for light chain and ig, TCR type
Describe case 3
Cells are immature as they are irregular and have nucleoli.
Most likely acute lymphoblastic leukaemia.
Describe case 4
You can see neutrophils and neutrophil precursors.
Toxic granules cannot also be seen which should be seen in infection.
Basophils and myelocytes can also be seen.
There has been an expansion of the myeloid cells so this is CML.
What else can cause an eosinophilia
Pulmonary eosinophilia.
Hodgkin’s disease, a cancer of the lymphatic system which may produce a reactive eosinophilia.
Describe the response to a pyogenic bacterial infection
Increase in cell numbers: Infection by pyogenic bacteria will result in tissue damage and the production and release of a range of inflammatory cytokines. Amongst these may be factors such as granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) that will stimulate granulocyte and monocyte production by the bone marrow. More importantly in the acute response there will be the early release from the BM of less mature cells.
This will result in an increase in the circulating granulocyte count and a left shifted appearance in the peripheral blood.
Chemotaxis: The phagocytes will circulate in the peripheral blood, at the site of infection they will move out of the circulation and into the tissues moving to the site of inflammation in response to chemotactic factors.
Phagocytosis: The neutrophils and monocytes will encounter foreign material that has been opsonised by immunoglobulin or complement. Using their Fc and C3b receptors they are able to recognise and phagocytose the foreign material.
Killing and digestion: Ingested material will be killed within the phagocytic vacuoles by both oxidative and non-oxidative mechanisms.
Describe the context of a lymphocytosis
When a lymphocytosis is identified in a FBC the blood film must be examined for the presence of:
A typical / reactive lymphocytesseenin mononucleosis syndromes.
Immediate response to acute stress (e.g. heart attack or other severe pain).
Small lymphocytes and smudge cells seen in chronic lymphocytic leukaemia.
Primitive blasts seen in acute lymphoblastic leukaemia.
Describe reactive lymphocytosis
Infection
EBV, CMV, Toxoplasma
infectious hepatitis, rubella, herpes infections
Autoimmune disorders
neoplasia
sarcoidosis
What are the causes of a reactive lymphocytosis
Infection
EBV, CMV, Toxoplasma
infectious hepatitis, rubella, herpes infections
Autoimmune disorders
neoplasia
sarcoidosis
