Antigens are substances that stimulate an immune response and react with the products of that response. They can be classified based on their origin (exogenous, endogenous, autoantigens, tumor antigens) and properties (immunogenicity, antigenicity, epitopes). Antigens are recognized by B cells and T cells and can stimulate both humoral and cell-mediated immunity. Adjuvants are substances that enhance the immune response to antigens.
History
Introduction
Classification of grafts
The Immunology of Allogeneic Transplantation
Genetics of graft rejection
Types of rejection
Recognition of Alloantigens
Effector Mechanisms of Allograft Rejection
Prevention of graft rejection
Graft versus host reaction
History
Introduction
Classification of grafts
The Immunology of Allogeneic Transplantation
Genetics of graft rejection
Types of rejection
Recognition of Alloantigens
Effector Mechanisms of Allograft Rejection
Prevention of graft rejection
Graft versus host reaction
Antibodies are immune system-related proteins called immunoglobulins. Each antibody consists of four polypeptides– two heavy chains and two light chains joined to form a "Y" shaped molecule. ... This variable region, composed of 110-130 amino acids, give the antibody its specificity for binding antigen.
T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response and are distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell surface.
B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system.. B cells produce antibody molecules.
In mammals, B cells mature in the bone marrow, which is at the core of most bones. In birds, B cells mature in the bursa of Fabricus.
B cells present antigens (they are also classified as professional antigen-presenting cells (APCs)) and secrete cytokines.
Antigen
Antigen is a substance which binds specifically with the products (antibodies, T-cells) of the immune system.
Its ability to bind with antibodies is called antigenicity.
Immunogen
It is a substance which produces an immune response as well as binds to its products.
So, immunogen is an antigen as well but antigen need not be immunogen.
The property of producing an immune response is called immunogenicity.
ANTIGEN, HAPTEN, ALL TYPES OF ANTIGENS, IMMUNOGEN , ATTRIBUTES OF ANTIGENICITY, DETERMINANTS OF ANTIGENICITY,
IMMUNOLOGY KUBY, MEDICAL MICROBIOLOGY & IMMUNOLOGY OF PANIKER , LIPPINCOTT'S IMMUNOLOGY, OTHER SOURCES.
Antibodies are immune system-related proteins called immunoglobulins. Each antibody consists of four polypeptides– two heavy chains and two light chains joined to form a "Y" shaped molecule. ... This variable region, composed of 110-130 amino acids, give the antibody its specificity for binding antigen.
T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response and are distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell surface.
B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system.. B cells produce antibody molecules.
In mammals, B cells mature in the bone marrow, which is at the core of most bones. In birds, B cells mature in the bursa of Fabricus.
B cells present antigens (they are also classified as professional antigen-presenting cells (APCs)) and secrete cytokines.
Antigen
Antigen is a substance which binds specifically with the products (antibodies, T-cells) of the immune system.
Its ability to bind with antibodies is called antigenicity.
Immunogen
It is a substance which produces an immune response as well as binds to its products.
So, immunogen is an antigen as well but antigen need not be immunogen.
The property of producing an immune response is called immunogenicity.
ANTIGEN, HAPTEN, ALL TYPES OF ANTIGENS, IMMUNOGEN , ATTRIBUTES OF ANTIGENICITY, DETERMINANTS OF ANTIGENICITY,
IMMUNOLOGY KUBY, MEDICAL MICROBIOLOGY & IMMUNOLOGY OF PANIKER , LIPPINCOTT'S IMMUNOLOGY, OTHER SOURCES.
What is antigen
What is epitope & paratope?
Classification of antigen
Pro antigen
Superantigens
Antigenicity
Determinants of antigenicity
Test for antigen detection
Here are five things to know about coronavirus tests: PCR and antigen tests are the most common but they work differently. While antigen tests look for proteins ...
An antigen is any substance that causes your immune system to produce antibodies against it. This means your immune system does not recognize the substance, and is trying to fight it off. An antigen may be a substance from th
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
2. 1 Concept of Antigen
• Antigens are substances that induce a
specific immune response and
subsequently react with the products of a
specific immune response.
3. • An antigen is a molecule that stimulates an
immune response.
• The word originated from the notion that they
can stimulate antibody generation. We now
know that the immune system does not only
consist of antibodies.
• The modern definition encompasses all
substances that can be recognized by the
adaptive immune system.
4. • Tolerogen - An antigen that invokes a
specific immune non-responsiveness due
to its molecular form. If its molecular form
is changed, a tolerogen can become an
immunogen.
5. • Allergen - An allergen is a substance that
causes the allergic reaction. The
(detrimental) reaction may result after
exposure via ingestion, inhalation,
injection or contact with skin.
6. Antigens can be classified in order of their origins
• Exogenous antigens
Exogenous antigens are antigens that have
entered the body from the outside, for
example by inhalation, ingestion, or injection.
By endocytosis or phagocytosis, these
antigens are taken into the antigen-
presenting cells (APCs) and processed into
fragments.
7. • Endogenous antigens
Endogenous antigens are antigens that have
been generated within the cell, as a result of
normal cell metabolism, or because of viral or
intracellular bacterial infection.
8. • Autoantigens
An autoantigen is usually a normal
protein or complex of proteins (and
sometimes DNA or RNA) that is
recognized by the immune system of
patients suffering from a specific
autoimmune disease.
9. These antigens should under normal
conditions not be the target of the immune
system, but due to mainly genetic and
environmental factors the normal
immunological tolerance for such an antigen
has been lost in these patients.
10. • Tumor antigens
Tumor antigens are those antigens that are
presented by the MHC I molecules on the
surface of tumor cells. These antigens can
sometimes be presented only by tumor cells
and never by the normal ones. In this case,
they are called tumor-specific antigens
(TSAs) and typically result from a tumor
specific mutation.
11. 2 Characteristics of Antigen
★ Immunogenicity
The capacity to stimulate the production
of antibodies or cell-mediated immune
responses.
12. ★ Antigenicity: The ability to bind antibody.
♣ Complete antigen
♣ Incomplete antigen, also known as
hapten.
13. Incomplete antigens have antigenic
determinants, but cannot induce immune
responses because they lack one or more of
the important attributes needed for this
function (one example of an incomplete
antigen is a hapten, which is an artificial
monovalent epitope)
14. 3 Properties of antigen
• Foreignness is essential to immunogenicity
because self-responsive cells are eliminated during
lymphocyte ontogeny, leaving only cells that
respond to non-self, so-called "foreign" epitopes.
• Specificity
• Degradability
– Ag processing by Ag Presenting Cells (APC)
15. • Genetics
– Species
– Individual
• Responders vs. Non-responders
• High molecular weight
• Chemical Composition
co-polymer, homo-polymer
16. 4 Antigenic epitopes
Epitope,or,Antigenic determinants, are
the portions of antigen molecules that
physically interact with paratopes
(combining sites) of immune response
molecules and therefore actually
"determine" antigen specificity
F
e
18. Types of Epitopes
1. Linear epitopes
♣ continuous and found in
polysaccharides as well as in both native
(nondenatured) and denatured proteins,
especially fibrillar proteins.
♣ specificity depends upon primary
sequence.
♣ typical size is 5-6 subunits in length.
19. 2. Conformational epitopes
♣ Discontinuous (involve multiple subunits,
often located far apart in the primary
sequence of the antigen molecule) and
are thus found only in native (globular)
proteins.
20. ♣ Specificity depends upon conformation, or
three-dimensional shape, which is a
combination of tertiary and quaternary
structure ... supported by primary and
secondary structure, of course.
21. ♣ Typical size is hard to pinpoint, but
sequences of up to 16 amino acids in
certain protein antigens have been shown
to interact with their complementary
paratope.
22. Two different epitopes
• B cell epitope, a
portion of antigen
molecule that is
recognized by B cell
receptors.
• T cell epitope, the
region of antigen
molecules that are
recognized by T cell
receptors.
26. 6 Superantigen
• Molecules that are potent T lymphocyte
mitogens and simultaneously bind to class
II MHC molecules. They are often
associated with staphylococcal products
and are involved in enterotoxemias and
toxic shock syndrome in humans.
27. • Superantigens (SAgs) are secreted
proteins (exotoxins) that exhibit highly
potent lymphocyte-transforming
(mitogenic) activity directed towards T
lymphocytes.
28. • Compared to a normal antigen-induced T-
cell response where 0.001-0.0001% of the
body’s T-cells are activated, SAgs are
capable of activating up to 20% of the
body’s T-cells. This causes a massive
immune response that is not specific to
any particular epitope on the SAg.
31. 7 Mitogen
• An agent that induces mitosis.
Here means to activate T cells and/or B
cells without help from APCs.
• Lectin, for example, concanavalin A
(ConA).
• LPS(lipopolysaccharide)
• Staphylococcal protein A(SPA)
32. 8 Adjuvant
• Adjuvant: The Latin "adjuvans" means to
help, particularly to reach a goal.
• An adjuvant is a substance that helps and
enhances the pharmacological effect of a
drug or increases the ability of an antigen to
stimulate the immune system.
34. Mechanisms of adjuvants
• Prolonged persistence of immunogen
molecules at the site of injection.
• Enhancement of co-stimulatory signals.
• Induction of granuloma formation.
• Stimulation of lymphocyte proliferation in a
non-specific manner.
35. 9 Other antigens
9-1 Heterophilic antigen : A kind of
common antigen, existing in human,
animals, and microbes.
Fossman antigen.
9-2 Xenogenic antigen
This antigen comes from different genus
and generic. For example, pathogenic
antigen.
36. 9-3 Allogenic antigen
The specific antigen exists in different
individuals. Blood type antigens
9-4 Autoantigen
A pathological term.
BUT, sperm antigen
37. 9-5 Idiotypic antigen
An antibody molecule is some sort of
foreign molecule when generated in
animal body. Such that immune
system recognizes it as Antigen,
which is known as Idiotypic antigen.
