Introduction to Immunology
The immune system is an astonishingly complex set of tissues, cells, and
specialized molecules which protect us from any foreign particles and microbes
that may enter our bodies. This series will focus on immunology, which is the
study of the immune system. Have you ever wondered what causes allergies? And
what is the deal with vaccines. How do vaccines work? Edward Jenner has largely
been credited with the development of the first vaccine against smallpox in 1796.
The principles of immunization had already been in practice across the world for
centuries. In the 9th century Ce, the Persian physician Al Rhazes noticed that
smallpox survivors were no longer susceptible to subsequent bouts of the disease.
In China, around 1000 ce, people learned that inhaling the powdered crusts of
smallpox scabs would protect them against future cases. The Russian zoologist
Elie Metchnikoff discovered phagocytes in 1883. We will work to understand what
the major components of the immune system are and how they work together to
provide defense against pathogens. We will learn about the structure of the
lymphatic system, which is made up of miles of specialized vessels that run
alongside blood vessels, and we will also talk about signalling molecules like
cytokines and chemokines which tell white blood cells where to go and what to do
during infection.
We want to understand what happens when the immune system doesn’t function
properly and actually harms us. Examine how antibodies develop and their
important applications in the world of biotechnology as research tools and
therapies against many kinds of diseases, and finally, throughout this series, we
will discuss some aspects of clinical immunology.
Myeloid and Lymphoid Lineages
Most immune cells originate in the bone marrow and develop from hematopoietic
stem cells. To become a white blood cell, a stem cell can follow one of two major
,lines of differentiation tracks. Macrophages are professional eaters of the immune
system. Neutrophils are the most numerous immune cell type in the blood and the
first type of immune cell to arrive on the scene when tissues become infected.
Eosinophils and basophils are much less common in the blood than neutrophils.
Mast cells are important for killing large parasites that are too big to be destroyed
by phagocytosis. These cells are also responsible for promoting allergies and
asthma. Dendritic cells patrol tissues for signs of infection so they can take
antigens back to structures called lymph nodes and activate T cells that will be able
to neutralize that kind of pathogen. The immune system is made up of billions of
myeloid-derived white blood cells that circulate in the bloodstream and patrol
tissues for signs of damage or infection. These cells communicate with each other
through cytokines and chemokines to carry out their diverse array of effector
functions which help destroy pathogens and heal damaged tissue.
Structure and Immune Function of the Lymphatic System
The immune system is made up of billions of cells distributed throughout the body.
To activate an immune cell, it must detect foreign molecules known as antigens.
These antigens are only present on foreign sources, diseased cells, or infectious
microbes. Moreover, the immune cells must receive multiple costimulatory signals
from other cells. These signals confirm the presence of a threat and prevent
immunity cells from overreacting in the event of a false alarm. Lymph is
transported through lymphatic vessels into small bean-shaped organs known as
lymph nodes. Every lymph node is encircled by a protective connective tissue layer
called the capsule. The organization of lymph nodes plays a vital role in
coordinating immune responses. Each node contains compartments for distinct cell
types, which ensures efficient identification of antigens and cell interaction. Unlike
lymph nodes, the spleen, the largest lymphatic organ, filters blood and holds an
essential reserve of blood. It removes old red blood cells from circulation and
filters immune complexes and pathogens from the blood. Roughly 75% of the
volume is the red pulp, composing of the cords of Billroth and venous sinus. The
, white pulp interspersed within the red pulp contains T cell zones and B cell
follicles.
MALT refers to multiple regions of lymphatic tissue with distinct features. In
addition to lymph nodes, MALT can be found in the tonsils, adenoids, and
appendix. These regions have B cell follicles and T cell zones, but also specialized
features based on the tissue type. Mucosal surfaces are particularly prone to
infection, so MALT is present to counteract this increased risk. The mucosa works
to prevent unnecessary activation of the immune response to harmless antigens. B
cells produce the antibody IgA, which helps prevent bacteria from crossing the
epithelial barrier without initiating an immune reaction. All of these mechanisms
work together to maintain the mucosal barrier, preventing infection without
necessitating an overactive immune response.
Immune cells
To learn about immune cells, we must understand their origin, which is the bone
marrow. The bone marrow contains pluripotent hematopoietic stem cells that
produce white blood cells called immature leukocytes. These will migrate to
different tissues to mature and activate. Modern progenitor cells divide and
produce megakaryoblasts, which give rise to platelets that play a critical role in
initiating haemostasis and tissue repair. Mast cells also have granules, but they are
not part of the granulocyte group because they do not circulate in the bloodstream.
Instead, they stay in the tissue. The bone marrow also releases monocytes that
circulate in the bloodstream after leaving the bone marrow. The T cell and B cell
are essential components of the adaptive immune system. They are both types of
lymphocytes. The lymphoid progenitor cell also produces B sub P cursors that
express only IgM antibodies present in the bloodstream.
Immunological organs and tissues
In the previous section, we discussed how the immune cells arise from the bone
marrow. Aside from the bone marrow, there are other organs in the lymphatic
The immune system is an astonishingly complex set of tissues, cells, and
specialized molecules which protect us from any foreign particles and microbes
that may enter our bodies. This series will focus on immunology, which is the
study of the immune system. Have you ever wondered what causes allergies? And
what is the deal with vaccines. How do vaccines work? Edward Jenner has largely
been credited with the development of the first vaccine against smallpox in 1796.
The principles of immunization had already been in practice across the world for
centuries. In the 9th century Ce, the Persian physician Al Rhazes noticed that
smallpox survivors were no longer susceptible to subsequent bouts of the disease.
In China, around 1000 ce, people learned that inhaling the powdered crusts of
smallpox scabs would protect them against future cases. The Russian zoologist
Elie Metchnikoff discovered phagocytes in 1883. We will work to understand what
the major components of the immune system are and how they work together to
provide defense against pathogens. We will learn about the structure of the
lymphatic system, which is made up of miles of specialized vessels that run
alongside blood vessels, and we will also talk about signalling molecules like
cytokines and chemokines which tell white blood cells where to go and what to do
during infection.
We want to understand what happens when the immune system doesn’t function
properly and actually harms us. Examine how antibodies develop and their
important applications in the world of biotechnology as research tools and
therapies against many kinds of diseases, and finally, throughout this series, we
will discuss some aspects of clinical immunology.
Myeloid and Lymphoid Lineages
Most immune cells originate in the bone marrow and develop from hematopoietic
stem cells. To become a white blood cell, a stem cell can follow one of two major
,lines of differentiation tracks. Macrophages are professional eaters of the immune
system. Neutrophils are the most numerous immune cell type in the blood and the
first type of immune cell to arrive on the scene when tissues become infected.
Eosinophils and basophils are much less common in the blood than neutrophils.
Mast cells are important for killing large parasites that are too big to be destroyed
by phagocytosis. These cells are also responsible for promoting allergies and
asthma. Dendritic cells patrol tissues for signs of infection so they can take
antigens back to structures called lymph nodes and activate T cells that will be able
to neutralize that kind of pathogen. The immune system is made up of billions of
myeloid-derived white blood cells that circulate in the bloodstream and patrol
tissues for signs of damage or infection. These cells communicate with each other
through cytokines and chemokines to carry out their diverse array of effector
functions which help destroy pathogens and heal damaged tissue.
Structure and Immune Function of the Lymphatic System
The immune system is made up of billions of cells distributed throughout the body.
To activate an immune cell, it must detect foreign molecules known as antigens.
These antigens are only present on foreign sources, diseased cells, or infectious
microbes. Moreover, the immune cells must receive multiple costimulatory signals
from other cells. These signals confirm the presence of a threat and prevent
immunity cells from overreacting in the event of a false alarm. Lymph is
transported through lymphatic vessels into small bean-shaped organs known as
lymph nodes. Every lymph node is encircled by a protective connective tissue layer
called the capsule. The organization of lymph nodes plays a vital role in
coordinating immune responses. Each node contains compartments for distinct cell
types, which ensures efficient identification of antigens and cell interaction. Unlike
lymph nodes, the spleen, the largest lymphatic organ, filters blood and holds an
essential reserve of blood. It removes old red blood cells from circulation and
filters immune complexes and pathogens from the blood. Roughly 75% of the
volume is the red pulp, composing of the cords of Billroth and venous sinus. The
, white pulp interspersed within the red pulp contains T cell zones and B cell
follicles.
MALT refers to multiple regions of lymphatic tissue with distinct features. In
addition to lymph nodes, MALT can be found in the tonsils, adenoids, and
appendix. These regions have B cell follicles and T cell zones, but also specialized
features based on the tissue type. Mucosal surfaces are particularly prone to
infection, so MALT is present to counteract this increased risk. The mucosa works
to prevent unnecessary activation of the immune response to harmless antigens. B
cells produce the antibody IgA, which helps prevent bacteria from crossing the
epithelial barrier without initiating an immune reaction. All of these mechanisms
work together to maintain the mucosal barrier, preventing infection without
necessitating an overactive immune response.
Immune cells
To learn about immune cells, we must understand their origin, which is the bone
marrow. The bone marrow contains pluripotent hematopoietic stem cells that
produce white blood cells called immature leukocytes. These will migrate to
different tissues to mature and activate. Modern progenitor cells divide and
produce megakaryoblasts, which give rise to platelets that play a critical role in
initiating haemostasis and tissue repair. Mast cells also have granules, but they are
not part of the granulocyte group because they do not circulate in the bloodstream.
Instead, they stay in the tissue. The bone marrow also releases monocytes that
circulate in the bloodstream after leaving the bone marrow. The T cell and B cell
are essential components of the adaptive immune system. They are both types of
lymphocytes. The lymphoid progenitor cell also produces B sub P cursors that
express only IgM antibodies present in the bloodstream.
Immunological organs and tissues
In the previous section, we discussed how the immune cells arise from the bone
marrow. Aside from the bone marrow, there are other organs in the lymphatic
