IMMUNOLOGY
INTRODUCTION
Our bodies are continually under
attack by millions of unseen foes, including viruses, bacteria, fungus,
parasites, and other disease-causing pathogens that can penetrate our bodies
and cause disease. Fortunately, most of us have a massive army on constant
alert with an effective armament ready to combat these intruders. The immune
system is that army.
DEFINITION:
Immunology is the study of the
immune system, which is made up of a complex network of cells, tissues, and
organs that communicate via a sophisticated and sensitive system.
EXPLANATION:
A variety of white blood cells (leukocytes)
and antibodies are always on the lookout for infections, ready to leap into
action and send out chemical instructions through the bloodstream. Immunologists
can improve the immune system's performance by better knowing what these cells
and molecules do and how they communicate with one another (for example, by
developing new vaccines). They can also figure out how to inhibit the immune
system from reacting to an inappropriate target, such as in allergies (a hyper
reaction to pollen or other allergens) or autoimmune illnesses (when the immune
system reacts against your own body).
Our bodies use three
primary ways to defend ourselves from infection:
By erecting nonspecific barriers
to prevent germs and viruses from taking hold. Skin, mucus discharges in the
respiratory and gastrointestinal systems, saliva, tears, and stomach acid are
all examples of these.
Beneficial bacteria that live in
the intestines and help digest specific types of food (known as the normal
flora) compete with pathogenic bacteria for food and space, reducing the
likelihood of disease-causing pathogens multiplying and causing sickness.
By relying on our innate immune
system to detect invaders that get past the first line of defense. Innate
immunity cells and other systems sense and respond to infections in a
nonspecific manner, and they do not provide long-term or protective immunity.
They are phagocytic ("eating") cells that ingest and consume
pathogens and particles. Phosphatic leukocytes include macrophages,
polymorphonuclear cells, dendritic cells, and mast cells. The natural killer
cell is a nonphagocytic member of the innate immune system (the part of the
immune system with specialized cells that identify and typically eradicate a
bodily invader before it can proliferate) (NK). The NK does not directly
assault a disease; instead, it destroys contaminated cells. Tumor cells are
also attacked by NK cells.
If pathogens get past the
barriers and phagocytes and start multiplying, a unique adaptive immune
response is activated. Adaptive immunity is based on our lymphocytes' unique
ability to discriminate between the body's cells (self) and undesirable
invaders (no-self) based on distinct self-markers on our cells. The natural
killer cell is a nonphagocytic member of the innate immune system (the part of
the immune system with specialized cells that identify and typically eradicate
a bodily invader before it can proliferate) (NK). The NK does not directly
assault a disease; instead, it destroys contaminated cells. Tumor cells are
also attacked by NK cells.
If pathogens get past the
barriers and phagocytes and start multiplying, a unique adaptive immune
response is activated. Because of different self-markers on our cells, our
lymphocytes have a remarkable ability to distinguish between the body's cells
(self) and undesirable invaders (no-self), which is the foundation of adaptive
immunity. When our immune self-defenses across organisms or cells with
"foreign" marks, they initiate an attack right away. The adaptive
immune response allows the immune system to detect a pathogen and mount a
stronger and faster attack each time the disease is encountered.
An antigen is something that can
cause an immunological reaction. A germ, such as a virus, or even a portion of
a microbe, can be an antigen. Antigens are no self-indicators carried by
tissues or cells from another person (excluding identical twins). This helps to
understand why tissue transplants are sometimes rejected. B cells and T cells
are the two main types of lymphocytes that make up our immune system. B cells
primarily function by secreting antibodies into the body's fluids. Antibodies
swoop down on antigens in the bloodstream. They are unable to penetrate cells,
though. T cells and other immune cells are in charge of fighting target cells,
whether they've been infected by viruses or have been warped by cancer.
T cells, unlike B cells, do not
identify antigens that are floating in the air. Rather, they have specific
antibody-like receptors on their surfaces that detect antigen fragments on the
surfaces of infected or malignant cells. T cells aid immune defenses in two
ways: some guide and regulate immunological responses, while others help to
suppress them. The cells, or helper T cells, communicate with other cells to
coordinate immune responses. Some activate surrounding T cells, while others
summon in phagocytes and stimulate nearby B cells to generate antibodies.
Killer T cells, also known as
CTLs or cytotoxic T lymphocytes, have a different purpose. By connecting to
other cells and delivering a fatal blast of chemicals that they safely carry
within small membrane "bags" called granules, these cells directly
assault other cells containing particular foreign or aberrant molecules on
their surfaces. CTLs are very effective against viruses that are developing
within infected cells. Small bits of these viruses peeking out from the Some of
the B cells and T cells that participated in the attack on a foreign invader go
on to become memory cells with a long lifespan. They can reproduce to mount a
faster and stronger immune response in a second encounter with the invader. The
scientific basis for immunization is this phenomenon.
The immune system's diverse cells
create and secrete a variety of chemicals that alert other cells to the
presence of an invader and aid in the activation of an immune response.
Histamine (which dilates blood vessels, produces inflammation, and draws
neutrophils and macrophages), interferons (which are released when viruses and tumor
cells are encountered), and interleukins (which are released when viruses and tumor
cells are encountered) are among them (which are vital to the functions of the
immune system). The cell membrane is recognized by CTLs, which start an attack
to kill the cell.
IMMUNOLOGICAL
SUBDISCIPLINES
Immunogenetics
This includes research on the
genetics (inheritance) of immunological responses, such as the Rh and ABO blood
groups, or the HLA system, which is vital in kidney and other transplants. The
field also looks into the genetics of an individual's antigen-response
capabilities.
Immunology in Clinical
Practice
From a medical standpoint, this
is the study of diseases produced by the immune system and disorders of the
immune system. The majority of these illnesses fall into one of three
categories: immunodeficiency, in which parts of the immune system fail to
respond adequately; autoimmunity, in which the immune system attacks its cells;
and hypersensitivity, in which the immune system reacts inappropriately to
harmless compounds (allergies and asthma) or responds inappropriately to
harmful compounds (allergies and asthma).
AIDS (acquired immunodeficiency
syndrome) is a classic example of an immune-system disorder. It is defined by
the absence of T helper cells and macrophages, both of which are killed by HIV
(human immunodeficiency virus).
Clinical immunologists also
research techniques to reduce organ transplant rejection and increase the
immune system's ability to combat cancer.
Immunology at the
molecular level
This mostly entails investigating
the chemicals released by cells that regulate immune cell migration and
activity. Chemicals that attract cells to an infection location and start the
inflammatory process are examples of such compounds.
Immunology of the Cells
T cells are the subject of this
research.
Immunology of the
Humoral
The focus of this research is on
B cells and the antibodies they make.