White Cells Flashcards
what are the three different types of granulocytes?
- basophil
- neutrophil
- eosinophil
where do granulocytes originate from
HSC → myeloid precursor → myeloblast → granulocytes
why do granulocytes have granules?
contain agents/proteins essential for their microbial function
e. g.
- neutrophils - enzymes to kill bacteria
- eosinophils - toxins to defend agains parasitic infections
- basophils - histamines + heparin (naturally occurring anticoagulant) + proteolytic enzymes (tissue breakdown)
what is the growth factor which encourage production/controls of granulocytes?
G-CSF (granulocyte colony-stimulating factor)
what is the growth factor which encourage/controls production of macrophages?
M-CSF
-causes neutrophil then macrophage production
what is the growth factor which encourage production/controls of granulocyte + macrophages?
GM-CSF
when would these growth factors be produced in increase amounts?
e. g.
- inflammation
- infection
how does a granulocyte mature?
myeloblast → divides into two myelocytes → nucleus becomes band/indented → neutrophil
overall: size gets smaller + development of granules
what dye do basophils take up?
basic (hence name)
what dye do eosinophils take up?
eosin
what dye do neutrophil take up?
basic + acidic dye in basic way
what is the main function of the neutrophil?
-defence agains infection through phagocytosis (mainly in tissues)
how do neutrophils work physiologically?
1) chemotaxis (cytokine attracts neutrophils)
2) adhesion + margination (to endothelium)
3) rolling along endothelium
4) diapedesis as they come out through the capillary wall
5) migration + phagocytosis of bacteria = kill bacteria or break down tissue
what is the main function of eosinophils?
defence against parasitic infections
spend even less time in the circulation than neutrophils
what is the main function of basophils?
involved in variety of immune and inflammatory responses
where do monocytes originate from?
HSC → myeloid stem cell → monoblast (myeloblast) → monocyte
what is the main function of monocytes?
-ingesting bacteria and present the broken down bacteria antigen on surface to lymphoid cells which will respond to the antigenic stimulus
what happens when they migrate into tissues?
-develop into macrophages
what are the key features of macrophages?
- largest of the granulocytes
- nuclei of erythroblasts inside
- bacteria inside macrophages
what are the functions of macrophages?
- scaveging functions
- store + release iron when they ingest old RBCs (ferritin + hemosiderin - storage forms of iron)
what is the origin of lymphocytes?
HSC → lymphoid stem cells → NK cells / small lymphocytes → B + T cells
what cells can b-lymphocytes mature into?
plasma cells (bigger than small lymphocytes, large Golgi zone where antibodies produced) → antibodies
which immunity are t-lymphocytes involved?
cell-mediated immunity
which immunity are NK cells involved?
innate → kill tumour cells + virus infected cells
What are the 2 main types of abnormalities that can occur in white cells?
-changes can be numerical, morphological or both
- leucocytosis (too many white cells e.g. neutrophilia)
- leucopenia (reduction in wbcs e.g. neutropenia)
Reasons for neutrophilia (too many neutrophils)?
1) infection
2) inflammation
3) infarction/tissue damage
4) myeloidproliferatuve neoplasm
5) pregnancy
6) exercise
7) after corticosteroids
neutrophilia + left shift connected non-segmented nucleuses
Reasons for neutropenia (too few neutrophils)?
1) chemotherapy + radiotherapy (as targets bone marrow)
2) autoimmune disorders
3) severe bacterial infections (strong pull so all neutrophils leaving bloodstream into tissues and BM can’t keep up)
4) viral infections
5) drugs
What happens to patients with very low neutrophil counts (< 0.5 × 109/l)?
high risk of serious infection e.g. sepsis
What is the name of a morphological abnormality a neutrophil could have?
neutrophil hypersegmentation
when there is an incr. in average number of neutrophil lobes
Reasons for Neutrophil hypersegmentation?
due to b12, folate deficiency
Reasons for Lymphocytosis (too many lymphocytes)?
1) viral infection
2) leukaemia
3) sometimes bacterial infections e.g. pertussis
Definition of lymphomenia and what type of cells it mainly consists of?
total lymphocyte count as less than 1x10^9/l
Reasons for Lymphopenia (too few lymphocytes)?
1) HIV
2) chemotherapy
3) radiotherapy
4) corticosteroids
5) severe infection
Reasons for Monocytosis (too many monocytes)?
1) infection (chronic)
2) chronic inflammation
3) some leukaemia
Reasons for Eosinophilia (too many eosinophils)?
1) allergy e.g. asthma
2) parasitic infection
3) leukaemia
Reasons for Basophilia (too many basophils)?
uncommon
1) leukaemia or related conditions
Summary: Transient leucocytosis is frequently associated with?
associated with infection
bacterial: neutrophilia / monocytosis
viral: lymphocytosis
parasitic: eosinophilia
Summary: Persistent leucocytosis may be caused by?
leukaemia
