INTRODUCTION TO IMMUNITY
Antigen
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Short word for antibody generation that means
that whenever an antigen enters in our body, an
antibody is produces.
Example: Corona virus, SARS-COV2 is the name
of the virus. Once the virus enters in our immune
system, in response to the particular virus
(considered as antigen) will produce antibodies.
Foreign substance that induce a host response
All around us in nature
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Tissue Cells
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Immunity
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Condition of being resistant to infection
Attenuation
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It means Thickening
Making a pathogen less virulent
Takes place through heat, aging or chemical
means
INNATE IMMUNITY
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Also known as natural immunity
The ability to resist infection by means of normally
present body functions
Example: Natural characteristic of our skin will
allow as to naturally resist infection.
Considered nonadaptive or nonspecific; responses
are the same for all pathogens or foreign
substance to which one is exposed.
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Leukocytes (white blood cells (WBC))
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Found in peripheral blood (mautre)
Play a key role in both innate and adaptive
immunity
Types
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Neutrophils
(51%-61%)Increases
of
bacterial infection neutrophil increases.
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Eosinophils (1% to 4%)- it has orange-red
granules for it is made up of major basic
protein called MBP that can be toxic for the
Resemble basophils but come from different
lineage
Play a role in allergic reactions
Can also function as APCs (antigen presenting
cells)
Can enhance and suppress the adaptive immune
response
Dendritic cells
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CELLS OF THE INNATE IMMUNE SYSTEM
Macrophages
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Play an important role in initiating and
regulating innate and adaptive immune
responses.
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Innate immune functions
o Microbial killing
o Anti-tumor activity
o Intracellular parasite eradication
o Phagocytes
o Secretion of cell mediators
Mast cells
ADAPTIVE IMMUNITY
A type of resistance characterized by specificity for
each individual pathogen, or microbial agent, and
the ability to remember a prior exposure.
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Specificity- if you have developed an
antibody against the hepatitis B surface
antigen, the antibodies called anti-HPS will
only work against Hepatitis B.
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Ability to remember a prior exposure- it
means to say it is the anamnestic response.
Our immune system has memory cells that
allow our immune system prior exposure to
the previous antigen.
helminths. Increases in allergic reaction and
parasitic infection.
Basophils (0% to 1%) - rarest type of WBC,
there are bluish-black that cover the entire
cytoplasm
Monocytes (2% to 6%)- can mature as
macrophages which is one of the examples of
antigen presenting cells.
Lymphocytes
Covered with long membranous extensions that
make them resemble nerve cell dendrites.
Are considered the most effective APC in the body
and the most potent phagocytic cell
Lymphocytes
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Represent between 20% and 40% of the
circulating WBCs
Types
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B cells- humoral immunity
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T cells- Cell mediated immunity
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Natural killer (NK) cells- large granular
lymphocytes and functions to target cells
(cells that had been virally infected)
ORGANS OF THE IMMUNE SYSTEM
Primary lymphoid organs
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Bone marrow (adult’s bursal equivalent)(for
children it is the fetal liver)
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One of the largest tissues in the body
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Fills the core of all flat bones
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Main sources of hemopoietic stem cells, which
develop into erythrocytes, granulocytes,
monocytes, platelets, and lymphocytes
Thymus
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Small, flat, bilobed organ found in the thorax
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Location for maturation of T lymphocytes
Secondary lymphoid organs
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Function as potential sites for contact with foreign
antigens.
Increase the probability of an immune response
Example: B cells ant T cells that does not
encountered any lymphocytes at all would die by
means of apoptosis, and they will be called naive
T cells or Naïve B cells.
Include:
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Spleen
o Approximately same size as a fist
o Red pulp
❖ Splenic tissue that makes up more
than one-half of the total value
❖ Destroy old red blood cells (RBCs)
when it reaches 120 days.
o White pulp
❖ Comprises about 20% of the total
weight of the spleen
❖ Contains lymphoid tissue arranged
around arterioles in periarteriolar
lymphoid sheath containing T cells
o Primary follicles
❖ Contain B cells not yet stimulated by
antigens (naïve cells)
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Lymph nodes
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Mucosal-associated lymphoid tissue (MALT)
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Cutaneous-associated lymphoid tissue (CALT)
LYMPH NODES
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Central collecting point for lymph fluid (white fluid
that circulate in the lymph node)
Lymphocytes and any foreign antigen enter nodes
via afferent lymphatic vessel (exit through
efferent)
Secondary follicles
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Consist of antigen-stimulated proliferating B
cells
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Location where transformation of B cells takes
place
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Form plasma cells (like antibody factor of our
body, eventually secretes antibody) and
memory cells (amnestic response) when
exposed to an antigen.
MALT AND CALT
MALT
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Found on mucosal surface of gastrointestinal,
repiratory and urogenital tracts
Main port of entry for foreign antigens
Numerous macrophages and lymphocytes present
CALT
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T cells, monocytes, macrophages and dentritic
cells found on skin.