Components of Immune ‫اجزاء سيستم ايمني‬
System
Lymphoid Organs ‫بافتها و اعضاء سيستم لنفاوي‬
Lymphoid Cells ‫سلولهاي لنفاوي‬
Lymphoid Cells ‫سلولهاي لنفاوي‬
White blood cells :
lymphocyte
Granulocytes: neutrophil eosinophil basophil
monocyte
Dendritic Cells
Natural Killer Cells (NK Cells)
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Figure 1-4 part 1 of 3
Macrophages
Figure 1-4 part 1 of 3
• (Greek: big eaters, from makros "large" + phagein
"eat"; abbr. MΦ)
• white blood cells within tissues, produced by the
division of monocytes
• Human macrophages are about 21 micrometres in
diameter
• Monocytes and macrophages are phagocytes, acting
in both non-specific defense (or innate immunity) as
well as to help initiate specific defense mechanisms
(or cell-mediated immunity) of vertebrate animals.
Dendritic cells (DCs)
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Immune cells and form part of the mammalian immune
system
Their main function is to process antigen
material and present it on the surface to other
cells of the immune system,
thus functioning as
antigen-presenting cells
(APC)
Dendritic cells are present in small quantities in tissues
that are in contact with the external environment,
mainly the skin (where there is a specialized dendritic
cell type called Langerhans cells) and the inner lining
of the nose, lungs, stomach and intestines. They
can also be found in an immature state in the blood
Figure 1-4 part 2 of 3
Neutrophil granulocytes
Figure 1-4 part 1 of 3
• Generally referred to as neutrophils
• Most abundant type of white blood cells in humans
• They form part of the polymorphonuclear cell family
(PMNs)
• Staining characteristics on hematoxylin and eosin (H&E)
neutrophils stain a neutral pink
• Normally neutrophils contain a nucleus divided into 2-5
lobes.
• Neutrophils are normally found in the blood stream.
• During the beginning (acute) phase of inflammation
(Bacterial infection & Cancers) neutrophils are one of the
first group of inflammatory cells to migrate toward the
site of inflammation, firstly through the blood vessels,
then through interstitial tissue
Eosinophil granulocytes
• Usually called eosinophils or, less commonly, acidophils
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• Responsible for combating infection and parasites in
vertebrates
• Along with mast cells, they also control mechanisms
associated with allergy and asthma
• These cells are eosinophilic or 'acid-loving‘
• The staining is concentrated in small granules within the
cellular cytoplasm, which contain many chemical
mediators, such as histamine and proteins such as
eosinophil peroxidase, RNase, DNases, lipase,
plasminogen, and Major Basic Protein.
• These mediators are released by a process called
degranulation following activation of the eosinophil, and
are toxic to both parasite and host tissues.
Figure 1-4 part 3 of 3
Basophils
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• The least common of the granulocytes
• Representing about 0.01% to 0.3% of circulating
leukocytes (white blood cells).
• The name comes from the fact that these are basophilic
• Basophils contain large cytoplasmic granules which
obscure the cell nucleus under the microscope
• They usually have 2 lobes in nucleus
• The mast cell, a cell in tissues, has many similar
characteristics. For example, both cell types store
histamine
• Like all circulating granulocytes, basophils can be
recruited out of the blood into a tissue when needed.
Mast Cells
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or Mastocytes
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Contains many granules rich in histamine and heparin
Although best known for their role in allergy and
anaphylaxis, mast cells play an important protective
role as well, being intimately involved in wound healing
and defense against pathogens
Mast cells settle in connective tissues and usually do not
circulate in the blood stream.
Figure 1-5
Lymphocytes
• A type of white blood cell in the vertebrate immune
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system
• By their appearance under the light microscope,
there are two broad categories of lymphocytes,
namely the large granular lymphocytes and the
small lymphocytes.
• The three major types of lymphocyte are T cells, B
cells and natural killer (NK) cells
• Functionally distinct subsets of lymphocytes
correlate with their appearance. Most, but not all
large granular lymphocytes are more commonly
known as the natural killer cells (NK cells). The
small lymphocytes are the T cells and B cells
T cells and B cells
Figure 1-4 part 1 of 3
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T cells and B cells are the major cellular components of the
adaptive immune response
T cells are involved in cell-mediated immunity
B cells are primarily responsible for humoral immunity
(relating to antibodies)
The function of T cells and B cells is to recognize specific
“non-self” antigens, during a process known as antigen
presentation
In response to pathogens some T cells, called helper T cells
produce cytokines that direct the immune response while
other T cells, called cytotoxic T cells, produce toxic granules
that induce the death of pathogen infected cells.
Figure 1-6
Natural killer cells (NK Cells)
Figure 1-4 part 1 of 3
• NK cells are a part of innate immune system
• Play a major role in defending the host from both
tumours and virally infected cells
• NK cells distinguish infected cells and tumours from
normal and uninfected cells by recognizing alterations
in levels of a surface molecule called MHC (major
histocompatibility complex) class I
• NK cells kill infected cell similar to cytotoxic cells
manner