Haematopoiesis and anaemias Flashcards
types of blood cells?
Red cells, Platelets, White cells
where and when does haematopeisis occur?
After birth, and during early childhood, hematopoiesis occurs in the red marrow of the bone. With age, hematopoiesis becomes restricted to the skull, sternum, ribs, vertebrae, and pelvis.
regulation of haematopoeisis
Regulated by variety of glycoprotein hormones, including stem cell factor, granulocyte-macrophage colony-stimulating factor, thrombopoietin and IL-3.
in normal peripheral blood, role of... -platelets - red cells - white cells
clotting
O2 transport
immunity + infection response
How do platelets work?
have no nucleus
The granules secrete substances which control clotting and the breakdown of blood clot
what do platelets form part of?
blood clot
What is a platelet’s life span
8-12 days, then removed by macrophages (WBC type) in the spleen and liver
What do low levels of platelets lead to
and what is it a side effect of?
Easy bruising and haemorrhage
chemotherpay/disease
types of white cells (leucocytes)
lymphoid cells (lymphocytes)
- T cells
- B cells
- NK cells
myeloid cells
- monocytes
- granulocytes
- eosinophils
- basophils
- neutrophils !!
What are granulocytes involved in
Innate immunity
How do neutrophils kill bacteria?
phagocytosis
engulf and destroy
granules contain lysosyme + myeloperoxidase.
ppl with too few neutrophils die of bac infection if not treated w antibiotics
where do neutrophils (type of granulocytes) live?
in blood for few hrs then migrate to tissues - cna live for 4-5 days
short. replaced
What do eosinophils do?
used in parasite infections (not phagocytic)
What do basophils do?
release histamine and heparin
hoe are eosinophils + basophils similar?
allergy/ atropy
What can monocytes do?
Migrate from blood into tissues and become macrophages
role in innate immnuity
how are monocytes similar to macrophages?
phagocytic
engulf+destroy dead cells, bacteria, protozoa, fungi
Where do T cells develop?
what are they and role?
T hymus
early progenitor for bone marrow but migrate and develop in thymus
what fo T cells exit thymus as?
naive cells - not yet exposed to antigen
where is thymus , role?
(gland behind sternum, in lungs - part of lymphatic system produces mature T cells)
what are (NK) lymphocytes?
small cells w low granularity (7-10 microM) by microscope
Where do B cells develop
Bone marrow
exit as naive cells
Where do Natural killer cells develop
bone marrow
what do T cells drive?
cell mediated immunity
what are dendritic cells
antigen presenting cells
work alongside T and B cells
What are mast cells
Cells that contain histamine, causes inflammation. Produced in the bone marrow but mature in tissues
allergy response
What is too few blood cells lead to?
Cytopenia
What is too many blood cells lead to?
Cytosis
normal values in blood of…
- red cells
- platelets
- neutrophils
- lymphocytes
red cells: 4.5-6.5 x 1012/L in M (lower in F)
… Hb more important 125 / 165 g/L
platelets: 150-400 x 109/L
neutrophils: 2.5-7.5 x 109/L
lymphocytes: 1.5-3.5 x 109/L
Describe the myeloid cells involvement in immunity.
granulocytes and monocytes
- neutrophils
live in blood for a few hours then migrate to tissues and live for 4-5 days
engulf and destroy bacteria (phagocytic)
granules contain lysosome and myeloperoxidase - eosinophils and basophils
both for allergy
eosinophils for parasite infections
less abundant - monocytes
migrate from blood into tissues and become macrophages
phagocytic; engulf and destory dead cells, bacteria, protozoa, fungi
Describe the two types of adaptive immunity.
humoral immunity: B cells = antigen specific antibodies
cell mediated immunity: T and NK cells = non specific
What is the lifespan of red cells, platelets, neutrophils and lymphocytes?
red cells: 120 days
neutrophils: <48 hours
platelets: 8-12 days
lymphocytes: years
whys chemotherapy done every 3 weeks?
as platelets and neutrophils are back at normal levels
lifespans:
neutrophils: <48 hours
platelets: 8-12 days
How long do eyrthrocyte transfusions, platelet transfusions and heamatopoietic stem cells last?
eyrthrocyte transfusions: 1 month - treatment of anaemia
platelet transfusions: few days
heamatopoietic stem cells: life long
What is haematopoiesis?
and When does haematopoiesis start?
blood cell production
starts 17 days after fertilisation and continues throughout life
regulated
What is leukaemia?
malignancies of haematopoietic cells arise in marrow and spread to involve blood/lymph nodes/spleen
4 types of haematologiccal malignancies?
leukaemias
lymphomas
myelomas
myeloproliferative disease + myelodysplasia
What is a lymphoma?
malignancies of lymphoid cells arise in lymph nodes/spleen and spread to involve blood and marrow
What is a myeloma?
malignancy of plasma cells (mature B lymphocytes) in marrow
can have multiple myeloma- multiple sites
What is myeloproliferative disease and myelodysplasia?
neoplastic chronic abnormal myeloid proliferation
maturation arrest causes what?
acute leukaemia
e.g. acute myeloid leukaemia (AML)
affects stem cells
proliferation of mature cells
when no maturation arrest –>?
over production of mature cells
e.g. chronic myeloid leukaemia (CML)
Classification of leukaemias
Lineage (Myeloid or lymphoid)
Maturation arrest or not: (acute or chronic)
Myeloid (AML or CML)
Lymphoid (ALL or CLL)
whys CLL (chronic lymphocytis leuk) different to all other leukaemias?
arises form mature cell (B lymphocytes)
What is a stem cell
cell that can differentiate and become any type of human cell
What are haemotopoietic stem cells (HSC)?
what about embryonic SC?
Multipotent
ESC = pluripotent can change to ANY cell in body
benefits of stem cell being able to divide indefinateky?
- can replenish itself
- give rise to specialised, differentiated cells
Where is the site of haematopoiesis in Infants
bone marrow
virtually all bones
Where is the site of haematopoiesis in adults
Bone marrow - axial skeleton
How to identify haemotopoetic cells
Cell markers
how is haematopiesis evaluated?
bone marrow biopsy - use local anaesthetci
hip bone surgery
in kids: sternum used
Name a condition in which monocyte cells will be elevated.
Allergy or Parasitic infection (Eosinophil).
What would a blood smear look like if theres no haematopoiesis?
hypocellular e.g. aplastic anaemia
no blood cells just fatty tissue
(trephine histology - best for cellularity)
How can you identify haematopoietic cells?
cell markers
CD (cluster of differentiation). standardised nomencalture (mainly leukocyte markers)
what does each hematopoietic cell have?
unique profile of markers (most names as CD)
diff functions - lineage / maturation/ function/ activation
whats immunophenotyping?
diff cells idnetified by diff monoclonal antibodies to cell markers
(usually by flow cytometry detecting fluorescent antibodies)
What do stem cells turn into?
mature blood cells
Where is the site of haematopoiesis in adults
Bone marrow - axial skeleton- skull + trunk
How can these haemotopiectic cells be identified
Monoclonal antibodies (immunophenotyping)
stem cells life
self renewal
or commitment…
maturation-> progenitor -> precursor -> mature
how is stem cell/ progenitor identified by?
functional assay
how is stem cell: precursor/ mature cell identified by?
routine marrow staining
how is stem cell at any stage of maturation identified ?
immunophenotyping
whats critical for haematopeiesis?
transcription factors
= proteins that control which genes turned on/off by binding to DNA + promoting/ blocking gene transcription
What effects do growth factors/cytokines have in hematopoiesis?
glycoproteins acting on specific receptors on haematopoeitic cells have multiple (pleiotropic) effects depending on cells
How can glycoproteins (G-CSF, a growth factor) affect haematopoesis
Proliferation Maturation Functional Activation Suppression of apoptosis
What are the key hormones in RBC and platelet production?
G-CSF
EPO
TPO (thrombopoeitin- platelet prodn)
whats EPO?
Erythropoetin (EPO)
HORMONE THAT STIMULATES RBC’S PRODUCTION
Growth factor in clinical use: G-CSF (2)
(recombinant SC injections) used for
- primary/ secondary preventions of infections in neutropenic patients (chemotherapy, congenital neutropenia)
- and to mobilise stem cells into periperal blood for stem cell harvest for stem cell transplants
whats is meant by
CSF
IL
colony stimulating factor
interleukin
How is erythropoiesis a negative feedback loop?
RBCs -> blood O2 content in lungs..
pO2 -> HIF-2 in kidney… EPO to erythroid precursors.
inc EPO = dec blood O2 content…
i.e. tissue oxygenation controls Epo production and Epo controls red blood cell (RBC) production, provides homeostasis in oxygen delivery to body tissues.
what in liver controls ion stores. and is inhibited by erythroferrone in epo loop?
hepcidin
What does a reticulocyte have and do?
has extruded nucleus but still has RNA.
can still make Hb (not possible in erythrocyte)
used to analsye causes of anemia
Growth factor in clinical use: EPO
(recombinant SC injections) used for imporvement of anaemia so transfusions not needed
mainly for end stage renal disease (endogenous epo low)