3.5 White Blood Cells Flashcards
Which white blood cells are produced from the common myeloid progenitor?
Granulocytes – neutrophils, basophils and eosinophils
What is the difference between monocytes and macrophages?
Monocytes migrate to tissues where they develop into macrophages
What are the main functions of neutrophils?
Chemotaxis and pathogen phagocytosis
What do neutrophils have?
Segmented (lobulated) nuclei
What granulocyte is this and why?
Basophil
Granules containing heparin, histamine and proteases
What are the main functions of basophils?
Mediation of type 1 hypersensitivity reactions, releasing histamine and leukotrienes
Modulation of inflammatory responses, releasing heparin and proteases
What is the main function of eosinophils?
Phagocytosis and defense against parasitic infection
What granulocyte is this and why?
Eosinophil
Bilobed nucleus and pink granules
What is a 2nd function of eosinophils?
Regulation of type 1 hypersensitivity reactions
Inactivates histamines and leukotrienes released by basophils and mast cells
What is left shift?
Presence of non-segmented neutrophil precursors due to increased bone marrow output
How many lobes is normal for a neutrophil?
3-5
What is it called when there are more than 5 lobes in a neutrophil?
Hypersegmented neutrophil
What are the steps of chemotaxis?
MARDi MP
Migration Adhesion Rolling Diapediesis Migration Phagocytosis
What is diapedesis?
When white blood cells migrate across the blood vessel wall
What is contained within the granules of basophils?
Heparin, histamine and proteolytic enzymes
What do monocytes do?
Phagocytose microorganisms coated in antibody and complement
Phagocytose bacteria and fungi
Present antigens to lymphoid cells
How are macrophages related to iron?
They store and release iron
What white blood cells are derived from the common lymphoid progenitor?
T cell, B cells and NK cells
Where and how do B lymphocytes develop?
Originate in bone marrow and foetal liver
Develop in the bone marrow and differentiate into plasma cells involving Ig light and heavy chain gene rearrangement
How do B cells mature?
After being exposed to antigens in lymphoid tissue
What do B cells do once mature?
Recognise non-self antigens which triggers production of specific Ig’s and antibodies (cell mediated immunity)
What are T cells involved in?
Cell mediated immunity
How are T cells developed?
Foetal lymphocyte progenitors migrate from the liver to the thymus to develop
What do NK Cells do?
Part of innate immunity
Kill tumour and virus infected cells
What is leukocytosis?
To many white blood cells of any type
What are transient and persistent leukocytosis caused by respectively?
Transient – infections
Persistent – leukemia
What is meant by neutrophilia, basophilia and eosinophillia?
Too many of each type of white blood cell
What is leukopenia?
Too little of any type of white blood cell
What is the most abundant type of white blood cell?
Neutrophils
What can cause neutrophilia? (NIICE PreT)
Neoplasm
Infection
Inflammation
Corticosteroids
Exercise
Pregnancy
Tissue damage
How does exercise increase the number of neutrophils?
Exercise causes a rapid shift of neutrophils from marginated pool to circulating pool
What might neutrophilia be accompanied with?
Left shift (increase in non-segmented neutrophil precursors) and toxic changes
What is toxic granulation of neutrophils?
Heavy coarse granulation of neutrophils
What causes neutropenia? (BRAID)
Benign ethnic neutropenia (people of African descent)
Radiotherapy
Autoimmune disorders
Infections (severe viral and bacterial)
Drugs (chemotherapy)
What is considered a low neutrophil count?
<0.5 x 10^9/L
What is lymphocytosis?
Too many lymphocytes
How to recognize lymphocytosis from a blood film?
Atypical lymphocytes (e.g. in Epstein Barr Virus infection)
Basophillic cytoplasm
Scalloped margins of WBC
What condition in children causes lymphocytosis?
Whopping cough
What causes lymphopenia?
HIV infection
Chemotherapy
Radiotherapy
Corticosteroids
What causes monocytosis?
Infection or chronic inflammation
What causes eosinophilia?
Allergy, parasitic infection, asthma, eczema
Can also occur in leukemia
What causes basophillia?
Usually in leukemia, otherwise uncommon
A 6-year old child is diagnosed with acute lymphoblastic leukaemia. The doctor warns the parents that their child is more susceptible to infections. Why is this the case?
Bone marrow is infiltrated with lymphoblasts, impairing haemopoiesis
How do macrophages form?
Common myeloid progenitor → monocytes → migrate to tissue → macrophages
Which white blood cell stores and releases iron?
Macrophages
What do B lymphocytes mature into?
Plasma cells which secrete antibodies
What is meant by reactive or secondary changes?
When a normal or healthy bone marrow responds to an external stimulus such as infection, inflammation or infarction
What is a primary blood cell disorder?
The leukocyte count or morphology is abnormal due to acquired somatic DNA damage affecting a haematopoietic precursor cell
This gives rise to blood cancers such as leukaemia, lymphoma, myeloma or myeloproliferative disorders
When might toxic granulation be seen?
During pregnancy
What causes chronic myeloid leukaemia?
Translocation occurs between ABL1 gene on chromosome 9 and BCR gene on chromosome 22
Chromosome 22 now has BCR-ABL1, becoming a philadelphia chromosome
Results in uncontrolled tyrosine kinase activity
Why does the fusion gene BCR-ABL1 cause CML?
The fusion protein has constitutive tyrosine kinase activity which drives autonomous blood cell proliferation
What happens to the spleen in CML?
Enlarged (splenomegaly)
How is CML treated?
Tyrosine kinase inhibitors
What cells are increased in CML?
All granulocytes and their precursors
What causes too many monocytes?
Infection (particularly chronic bacterial infection) or chronic inflammation
What might lymphocytes due to a viral infection look like?
Intensely basophilic cytoplasm, scalloped margins and hugging of the surrounding red blood cells
What cell type is characteristic of chronic lymphocytic leukaemia?
Smudge cells
What are some haematological features of acute lymphoblastic leukaemia?
Leukocytosis with lymphoblasts in the blood
Normocytic, normochromic anaemia
Neutropenia
Thrombocytopenia (low platelet count)
Replacement of normal bone marrow cells by lymphoblasts
Why might a child with acute lymphoblastic leukaemia have bruising and be pale?
Bruising is due to thrombocytopenia
Paleness is due to anaemia
Both occur due to the replacement of normal bone marrow cells with infiltrating lymphoblasts
What are the treatment options for ALL?
Supportive Red cells Platelets Antibiotics Systemic chemotherapy Intrathecal chemotherapy
What are clinical features of leukemia due to accumulation of abnormal cells?
Leukocytosis
Bone pain in acute leukemia
Splenomegaly, hepatomegaly, lymphadenopathy, thymic enlargement
Skin infiltration
What are clinical features of leukemia due to the metabolic effects of leukemic cell proliferation?
Hyperuricaemia and renal failure
Weight loss
Low grade fever
Sweating
What are clinical features of leukemia due to abnormal haemopoiesis?
Fatigue, pallor, breathlessness (anaemia)
Fever, other features of infection (neutropenia)
Brusing, petechiae, bleeding (thrombocytopenia)
Mutations in what genes usually cause acute myeloid leukaemia?
Mutations in transcription factors for multiple genes causing profoundly disturbed cell behaviour
What does acute myeloid leukemia result in?
Reduced haemopoiesis
