Leukocytes
They are responsible for both specific and non
specific immunity.
Leuko-white ; cytes- cells
They are originated from pluripotent stem cells in
the liver
There are two types of leukocytes based on
presence of nucleus.
Agranulocytes: cell without granules .It have two
types
Monocytes, Lymphocytes
Monocytes
Single-cell,
Kidney shaped nucleus,
Produced in bone marrow,
The mature form of monocytes is called Macrophage.
Monocytes
– Circulate in the blood.
Macrophages
–Circulate in the tissues.
Macrophage is useful to carry out Phagocytosis.
Lymphocytes
Divided into 3
types: T
cell, B cell & NK cell
B lymphocytes or B
cell - mature in bone marrow-circulates in the blood-reach
to various lymphatic organs & Activated
This activated mature B cell is called Plasma cells.
Plasma cell secretes large quantity of glycoprotein
which is called Antibodies.
T- lymphocytes or T- cell
It is produced in Thymus gland-circulate in the
blood-reach to the lymphatic organs
It requires Specific antigen to bind
It do not secretes antibody
Activated T cell produced & secretes some proteins
called Cytokines.
Natural Killer (NK) cells
They
play important role in cell cytotoxicity.
They also play important role in innate immune
response
They are non-phagocytic cells
2. Granulocytes or Polymorphonuclear (PMN) Leukocytes
A
group of white blood cells is collectively referred to as granulocytes or Polymorphonuclear
leukocytes (PMNs).
Granulocytes are composed of three cell types
as
Neutrophils, Eosinophils, Basophils.
These
cells are important in the removal of bacteria and parasites from the body.
They
engulf these foreign bodies and degrade them using their powerful enzymes.
Neutrophils
Neutrophils
constitutes 50-70% of the circulating WBC’s.
Life span 2-4 days in tissue.
They
are first cell to arrive to the infection site.
It
plays important role in inflammatory response.
Phagocytic
and bactericidal.
Leucocytosis
Eosinophils
Eosinophil
constitutes 1-3 % of the circulating WBC’s.
Important in anti-parasite defences.
It
presents Antigen to T cell in body.
Release of contents present in Eosinophils can
damage the parasite membrane.
Eosinophils are associated with allergic
diseases.
Basophils
Only
present in the bloodstream, and represent <1% of circulating WBC.
They
are non-Phagocytic cells.
They play a major role in the allergic
response.
They
release their granules (containing histamine, serotonin, heparin,
prostaglandin, etc into the bloodstream following exposure to specific
allergens).
When an individual is exposed to an allergen,
specific IgE is produced. This IgE binds to the surface of basophils.
Mast cells
Mast
cells are released from the bone marrow as undifferentiated precursor cells and
do not differentiate until they enter the tissues (skin, connective tissue,
mucosal epithelium, etc.)
Play
a very important role in the development of allergic response.
They
produce a variety of cytokines.
Dendritic cells
Originate
in the bone marrow
Function as antigen presenting cells (APC).
Four types of dendritic cells are – Langerhan’s
cells, Interstitial dendritic cells, Myeloid cells, Lymphoid dendritic cells.
-Siddhi Shah
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