Transcript Lecture 16+17, Introduction to Immunology

Introduction to Immunology
‫علم المناعة‬
Immunology
• Immunology is a branch of biomedical science that covers
the study of all aspects of the immune system in all organisms.
)‫مناعة (حصانة‬
Immunity
Immunity is a biological term that describes a state of having
sufficient biological defenses to avoid infection, disease, or
other unwanted biological invasion.
What does the Immune System
protect against?
Potentially pathogenic organisms
•
Bacteria: Extracellular / (intracellular)
•
Viruses:
•
Fungi: Mostly extracellular
•
Parasites: Extracellular or intracellular
Obligate intracellular parasites
Primary function of the Immune System:
To protect individuals against infection
- must be able to distinguish
‘self ‘ from ‘non-self’
Dysfunctions:
Immunodeficiency
Allergy
Autoimmunity
‫المناعة‬
‫‪Immunity‬‬
‫المناعة المكتسبة (التكيفية)‬
‫‪Adaptive immunity‬‬
‫المناعة الطبيعية‬
‫‪Innate immunity‬‬
‫المناعة الطبيعية‬
Innate immunity
• The innate immune system, also known as non-specific
immune system.
• It is first line of defense, comprises the cells and
mechanisms that defend the host against infections by
other organisms.
• Innate immune systems provide immediate defense against
infection.
‫المناعة المكتسبة‬
Adaptive (acquired) immunity
The adaptive immune system, also known as the specific immune
system.
• It is composed of highly specialized, systemic cells and processes
that eliminate or prevent pathogens.
• It is activated by the “non-specific” innate immune system.
• The adaptive immune response provides the vertebrate immune
system with the ability to recognize and remember specific
pathogens (to generate immunity), and to mount stronger attacks
each time the pathogen is encountered.
Innate and Adaptive Immune Systems
Innate
Rapid, first line of defence against infection
Adaptive
Later, more specific response
Innate vs. adaptive immune systems
Response
Innate
Adaptive
Kinetics
Rapid (early)
Slow (late)
Specificity
+
+++
Memory
-
+++
‫أنماط المناعة‬
‫‪Type of immunity‬‬
‫عندما يهاجم كائن حي فأن لديه وسائل عديدة للدفاع عن نفسه هي‪:‬‬
‫المناعة السلبية‬
‫‪Passive Immunity‬‬
‫•مناعة سلبية يتم أساسا من خالل أم إلى الرضيع‬
‫أو الجنين‪.‬‬
‫•المناعة السلبية تأتي في المقام األول من األم‬
‫)‪ (IgG antibodies‬إلى الطفل أو الجنين‪.‬‬
‫•أيضا يمكن انتقالها على طريق الرضاعة من‬
‫حليب األم‪.‬‬
‫•الطفل يملك المناعة من األم لكنها ال تدوم إال‬
‫بضعة أشهر ألن الطفل لم تتطور مناعته الخاصة‬
‫به‪.‬‬
‫المناعة اإليجابية (اللقاحات)‬
‫) ‪Active Immunity (Vaccines‬‬
‫* المناعة الطبيعية تكتسب من التطعيمات أو من اإلصابة ضد‬
‫مسببات المرض‪ .‬وفي المرة القادمة التي يهاجم نفس الكائن الممرض‬
‫جسمك يكون قد تمكنت الذاكرة المناعية من بناء ذاكرة للمرض ومن‬
‫ثم القدرة على صده بكفاءة عالية‪.‬‬
‫* تستخدم ألغراض صحية وتكون بتعريض أجسادنا إلى مستضد‬
‫معين‪ .‬هذه المستضدات عادة ما تقتل أو تضعف لتقليل قوتها‪.‬‬
‫وبعد تدمير هذه العوامل الممرضة الجسم يخزن بعض خاليا تي‬
‫كخاليا ذاكرة‪ .‬ويرجع بالفعل إلى هذه الشفرات أو الرموز‬
‫(المستضدات المعينة) عندما يحتاجها الجسم‪ .‬هذه الذاكرة في خاليا‬
‫تي يمكن أن تكون وسيلة الكتساب المناعة بشكل مصطنع بينما‬
‫هجوم حقيقي ممرض يكسب بطبيعة الحال نوع من المناعة‪.‬‬
Types of Immunity
Active Immunity (Vaccines )
• Active immunity is acquired from vaccinations or
from infection against a pathogen. The next time
you encounter the same pathogen your body has
built memory against it and will be able to fight it
much more efficiently.
• Used for health purposes to expose our bodies to a
particular antigen. These antigens are usually killed
or severely weakened to decrease their potency.
After destroying these pathogens, the body stores
some T cells as memory cells, due to the fact they
code for a particular antigen and can be when
needed. This memory in T cells can be a means of
artificially acquiring immunity while a genuine
attack by a pathogen is a naturally acquired type of
immunity.
•
•
•
•
Passive Immunity
Passive immunity is primarily
through a mother to a baby or
fetus.
Through the placenta the mother
transfers her immunity (IgG
antibodies) to her fetus.
Also through breast milk.
The baby has her/his immunity
from the mother but it only lasts a
few months because the baby
hasn't developed his/her own
immunity.
SUMMARY
Immunity
Innate
Acuired
Passive
Artificial
Natural
Active
Artificial
Natural
Antigen and antibodies
Antigens
• Antigens These are any foreign
substance which can stimulate the
immune system of our body.
• They may be pollen, pathogens,
spores, proteins, carbohydrates,
nucleic acids or lipids.
• In short, antigens are the harmful
substances which may disrupt the
normal functioning of our body.
• In order to stop this disruption, our
body produces antibody to protect
itself and destroy the antigens.
•
Antibodies
• Antibodies are a glycoproteins
found in our body, also known as
Immunoglobins (Ig).
• This protein is produced in
response to antigens.
•
In short, they produced by the
army of our body to encounter
specific foreign substances which
invade the body.
In short, antigens cause the disease and antibodies cure it.
‫تركيب الجسم المضاد‬
Structure of an Antibody
• Antibodies are Y-shaped proteins with four
polypeptide chains.
• The two polypeptide chains are long and identical
whereas the other two are also identical but short.
• The long chains are known as Heavy chains or H
chains and the short chains are known as Light
chains or L-chains.
• Both the chains are held together by disulphide
bonds like magnets.
• Both chains have a distinct region and a variable
region. This variable region is the one where all the
action occurs. It acts like a lock and key mechanism,
and is used to combine with antigens in a death
wrap. This action site is also known as paratopes.
Parts of an Antibody
Classes of immunoglobulin 1
• Five Classes IgG, IgM, IgA, IgD and IgE.
• All have the same basic antibody structure.
• The polypeptide sequence in the heavy chain
constant regions are different, giving different
functional characteristics
Classes of immunoglobulin 2
1.
2.
3.
4.
5.
IgG - Gamma (γ) heavy chains
IgM - Mu (μ) heavy chains
IgA - Alpha (α) heavy chains
IgD - Delta (δ) heavy chains
IgE - Epsilon (ε) heavy chains
Classes of immunoglobulin 3
• IgA– This immunoglobin protects the body against gastro-intestinal
and respiratory problems. It is commonly found in secretion;
colostrum and saliva.
• IgD- This antibody activates the B cell after interacting with any
antigen. Found on the surface of circulating B lymphocytes often
co-expressed with IgM.
• IgE – This antibody controls allergic reactions.
• IgG- These are extremely important antibodies which stimulate
phagocytes. Placental transfer. Predominant Ab of a secondary
immune response
• IgM – This is the largest antibody. Predominant Ab of primary
immune response. Found at B lymphocyte cell surface