Spleen+White Cells Flashcards
What are the functions of the spleen?
Sequestration and phagocytosis – old/abnormal red cells removed by macrophages
Blood pooling – platelets and red cells can be rapidly mobilised during bleeding
Extramedullary haemopoiesis – pluripotential stem cells proliferate during haematological stress or if marrow fails (eg myelofibrosis)
Immunological function – 25% of T cells and 15% of B cells are present in the spleen
How is splenomegaly examined?
- never normal to palpate spleen below costal margin
- start palpating at RIF and feel for splenic notch
- spleen moves towards you on inspiration
splenomegaly presents with vague abdominal pain and reduced ability to eat
What are some potential causes of splenomegaly?
- Back pressure (e.g. portal hypertension in liver disease)
- Over working red pulp
- Over working white pulp
- Reverting to what it used to do (extra medullary haemopoiesis)
- Expanding as infiltrated by cells which shouldn’t be there
- Cancer cells of blood origin eg leukaemia
- Other cancer metastases
- Expanding as infiltrated by other material e.g Gauchers disease, sarcoidosis
What are some potential consequences of splenomegaly?
- pancytopenia/thrombocytopenia due to pooling of blood in enlarged spleen (hypersplenism)
- risk of rupture if enlarged and no longer protected by ribcage
What is hyposplenism?
-lack of functioning splenic tissue
caused by:
- splenectomy
- SCD
- coeliac disease
blood film reveals howell jolly bodies. patients are at risk of overwhelming sepsis particularly from encapsulated organisms.
What is the role of neutrophils?
the first-responder phagocyte, the commonest white cell, essential part of innate immune system, respond to cytokines/chemokines
What is the role of monocytes?
- Response to inflammation and antigenic stimuli
- Migrate to tissues – macrophages
- lysosomes contain lysozyme, complement, interleukins, arachidonc acid, CSF
- phagocytosis, pinocytosis
What is the role of eosinophils?
-Responsible for dealing with some parasites
-Mediator of allergic response
-Migrate to epithelial surfaces
-Granules contain arginine, phospholipid, enzymes
-Phagocytosis of antigen - antibody complexes
-Mediate hypersensitivity reactions eg to drugs, in
asthma, skin inflammation
What is the role of basophils?
-active in allergic reactions and inflammatory
conditions
-Dense granules contain histamine, heparin, hyaluronic acid, serotonin
What is the role of lymphocytes?
• Originate in bone marrow
B cells (humoral immunity) – antibody (immunoglobulin) forming cells
Natural killer cells (cell mediated cytotoxicity)
T cells (cellular immunity) CD4+ helper cells, CD8+ cells
What are some causes of neutrophilia?
- tissue damage
- acute inflammation
- cancer
- G-CSF
- acute haemorrhage
- drugs e.g steroids
- smoking
- metabolic/endocrine disorders
- infection
What are some causes of neutropenia?
reduced production due to factors such as b12/folate deficiency,, infiltration of bone marrow by malignancy/fibrosis, aplastic anaemia, radiation, drugs, viral infection
immune destruction
sepsis
splenic pooling
consequences are sever life threatening bacterial /fungal infection & mucosal ulcerations
What are some causes of monocytosis?
- chronic inflammatory conditions e.g RA, Crohns
- chronic infection e.g TB
- carcinoma
- myeloproliferatice disorders
What are some causes of eosinophilia?
- allergic diseases
- drug hypersensitivity
- churg-strauss
- parasitic infection
- skin diseases
- hodgkin lymphoma
- acute lymphoblastic leukaemia
- acute myeloid leukaemia
- eosinophilic leukaemia
- idiopathic hypereosinophilic syndrome
What are some causes of basophilia?
- reactive e.g immediate hypersensitivity reactions
- UC
- RA
-myeloproliferative causes
