WBC disorders Flashcards
what is neutrophil leukocytosis?
an increase in the circulating neutrophils to a level greater than 7.5 x 10(9)/L and is a blood finding
what causes neutrophilia?
- Bacterial infections
- Inflammation of tissue and necrosis
- Metabolic disorders
- Neoplasms
- Acute haemorrhage, haemolysis
- Drugs
- Chronic myeloid leukaemia, myeloproliferative disease such as polycythaemia rubra vera, myelofibrosis, essential thrombocythaemia
- Treatment with myeloid growth factors G-CSF, GM-CSF
- Asplenia
what is a leukamoid reaction?
a white cell count > 50 x 109/L with cells of all stages of myeloid maturation appearing in the peripheral blood
when does a leukamoid reaction occur?
reactive response to severe infection, certain cancers, pharmaceuticals, growth factors, haemorrhage or haemolysis
what is neutropenia?
when the neutrophil count is less than 2.5x109/L
what are the causes of neutropenia?
can be congenital or acquired:
- Congenital- kostmann’s syndrome
- Acquired: Drug induced, Cyclical neutropenia, Immune infections
reference range for eosinophils?
0.02 - 0.5 x 109 /L
what is the role of eosinophils?
They are phagocytic and can kill ingested organisms
They are important in the bodies defence against tissue parasites (hook worms and tape worms)
They also have a role in allergic reactions
what do eosinophils secondary granules contain?
high concentrations of bactericidal proteins and enzymes
what are the main bactericidal proteins and enzymes in eosinophils?
Major basic protein (MBP)
Eosinophil peroxidase
Eosinophil cationic protein (ECP)
Eosinophil derived neurotoxin/eosinophil protein X (EDN/EPX)
what does major basic protein MBP do?
disrupts the lipid bilayer of parasites
what are the causes of eosinophilia?
Allergic disease Parasitic infections Certain skin conditions Drug sensitivity Graft versus host disease Hypereosinophilic syndrome Chronic eosinophilic leukaemia Treatment with GM-CSF
reference range basophils
0.2-0.1 x 109 /L
role of basophils
They are a role in allergic and inflammatory response and synthesis heparin
where are basophils and mast cells found?
Basophils comprise of <1% of circulating WBC whereas mast cells are resident in the tissues
what are the mast cell precursors?
basophils
what stimulates basophils and mast cells to release their granules?
IgE antibodies
what causes basophillia?
Chronic myeloid leukaemia
Reactive basophils increases are sometimes seen in myxoedema, smallpox, or chickenpox infection
Allergic reactions
monocyte reference range
0.2-1.0 x 109 /L
role of monocytes
These cells function as part of the body’s defences against bacterial and fungal infections
They are phagocytic and secrete chemical messengers known as cytokines
what are the functions of the tissue macrophage?
- Microbial killing
- Removal of debris such as dying cells, particulate material such as coal dust, silica and carbon
- Immune response where macrophages play a role in processing antigens to facilitate recognition by other immune cells
causes of monocytosis?
Chronic bacterial infections such as TB or brucellosis Fungal or viral infections Connective disease such as SLE or RA Protozoan infections Chronic neutropenia Some haematological malignancies Treatment with GMCSF
where do the lymphocytes develop?
the bone marrow and thymus
lymphocyte reference ranges
1.0 - 3.0 x 109 /L
percentage of T vs B lymphocytes
T lymphocytes (70-80%) B lymphocytes (20-30%)
what are the secondary lymph organs?
Lymph nodes, spleen, lymph follicles in tonsils, adenoids, peyer’s patches and MALT
what is MALT?
a diffusion of lymphoid tissue found in various sites in the body such as the GIT, thyroid, breast, lung, salivary glands, eye and skin
What is GALT?
Gut Associated lymphoid Tissue GALT is part of the gastrointestinal tract immune system
where are b cells produced?
starts in foetal liver and then continues in bone marrow
what is the role of b lymphocytes?
the production of antibodies (immunoglobulins) which are proteins designed to bind to foreign antigens
what type of immunity do b lymphocytes provide?
adaptive antibody mediated immunity
Also referred to as humoral immunity
from what do mature t cells develop in the thymus?
prothymocytes
do t cells produce immunoglobulin?
no
what is the role of t cells?
T cells have a major role to play in cell mediated immunity. T cells are divided into sub populations, cytotoxic t cells, t helper cells and t suppressor cells, memory t cells each having specific roles in the immune response
what hormone leads to the formation of the mature t lymphocytes?
thymosin produced by the thymus
what occurs when an antigen is presented to a t lymphocyte?
stimulates the proliferation (clonal expansion) of the t lymphocyte into 4 main types of specialised t lymphocytes
what are the 4 types of t cells?
- Memory t cells
- Cytotoxic t cells
- Helper t cells
- Suppressor t cells
what are memory t cells?
Long lived cells that survive after the threat of the cell carrying the foreign antigen has been neutralised
Provide cell mediated immunity in the future by responding rapidly to another encounter with the same antigen
what are cytotoxic t cells?
Directly inactivate any cells carrying the foreign antigen
They attach themselves to the target cell and release powerful toxins, resulting in the destruction of the target cell carrying the foreign antigen
function of helper t cells?
Production of cytokines eg interleukins and interferons which support and promote cytotoxic t lymphocytes and macrophages
Cooperation with the b lymphocytes enabling them to produce antibodies
how do helper t cells effect b cells?
although b lymphocytes are responsible for antibody manufacture they require to be stimulated by a helper t lymphocyte first
what are suppressor t cells?
Act as the brakes turning off activated t and b lymphocytes
do b cells need antigens to be presented to them by APCs?
no, only t cells
what are the types of b cells?
plasma cells and memory cells
what do antibodies do?
Bind to antigens labelling them as targets for other defence cells, such as cytotoxic t lymphocytes and macrophages
Bind to bacterial toxins neutralising them
Activate complement
