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Morphology of Leukocytes:

Visit:
Inflammation
;
Acute Inflammation
;
Types of Acute Inflammation
;
Chemical Mediators
;
Chronic Inflammation
;
Wound Healing
.
1. Neutrophils:
Neutrophils
predominate in acute inflammation and appear within 6 to 12 hours of
onset. They are short lived and die within 24 to 48 hours. They liberate
Lysosomal enzymes,
Leukotrienes
, Prostaglandins , Slow Reacting
Substance of Anaphylaxis (SRS- A), and Platelet activating factors.
2.
Macrophages:
These appear after neutrophils, at the
site of acute inflammation, in subsequent 24 to 48 hours and is short
lived. It is activated resulting in increased cell size, increased
content of lysosomal enzyme and greater ability to kill ingested
microbes and tumour cells. After the inflammation is cleared, it dies or
removed through lymphatics causing regional lymphadenitis. Closely
related cells are present in the bone marrow, circulating blood
monocytes , tissue macrophages, sinus histiocytes in liver (Kupffers
cell), spleen and lymph nodes, central nervous system (microglia)
and lungs (alveolar macrophages).
3. Lymphocyte:
It releases Cytokines,
Leukotrienes,
and Prostaglandins. Immune granulomas are Type-IV hypersensitivity
mediated by T-lymphocytes. T- lymphocytes have a reciprocal relationship
to macrophages in chronic inflammation.
4. Plasma cells:
Plasma
cell with eccentric nucleus
These are round or oval cells with
cart-wheel, eccentric nucleus and formed from lymphoblasts. It forms
most of the Immunoglobulins.
5.
Eosinophils:
These are found in inflammatory sites
around parasitic infections or immune reactions mediated by IgE. (
Example: Allergy). It contains a protein toxic to parasites and
epithelial cells.
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Definitions:
Leukocytosis
means
leukocyte count more than normal (11.0
x109/L leukocytes).
It is mainly seen in bacterial infection.
Leukemoid reactions
are characterized
by high leukocytosis (the
WBC count is often in a range of 50.0-100.0 x10 9/L
) and is associated
with
blasts, promyelocytes, myelocytes, and metamyelocytes in the
peripheral blood.
Neutrophilia
is seen mainly in bacterial infections.
Example: Lobar
Pneumonia
Eosinophilia
is usually seen in
parasitic infections. Example:
filariasis
; allergic conditions like
bronchial asthma
.
Monocytosis
occurs in some virus
infections. Example:
Infectious Mononucleosis
Lymphocytosis
is seen in some viral infections.
Example:
Mumps
,
Rubella .
Leukopenia
is seen in most
viral, rickettsial, and protozoal infections and some bacterial
infections. Example:
typhoid fever.
It is also seen in overwhelming infection and in debilitated
patients. |

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