Cell-Mediated (Cellular) Immunity [aka T-cell immunity] - Physiology & Immunology
Summary
TLDRIn this educational video, Medicosis dives deep into the intricacies of the immune system, focusing on cellular immunity driven by T lymphocytes. The script explains the roles of B lymphocytes in defending against bacteria and T lymphocytes in combating viruses and fungi. It explores the communication between immune cells via cytokines, the significance of MHC in T cell activation, and the importance of recognizing self from non-self to prevent autoimmune diseases. The video also touches on the challenges of organ transplants, the prevention of organ rejection, and the complications of hemolysis, offering a comprehensive overview of immunology.
Takeaways
- π¬ B lymphocytes mainly defend against bacteria, while T lymphocytes defend against viruses and fungi.
- π¦ Plasma cells, derived from B lymphocytes, secrete antibodies which neutralize antigens and activate various immune responses.
- π§ͺ There are three complement pathways: classical, alternative, and mannose-binding lectin.
- 𧬠Cytokines, such as interleukins, colony-stimulating factors, and tumor necrosis factor, help immune cells communicate.
- π Antigen-presenting cells present antigens to lymphocytes, which then activate B and T lymphocytes.
- βοΈ T helper cells (CD4) assist other immune cells, while T cytotoxic cells (CD8) directly kill infected or cancerous cells.
- π Major Histocompatibility Complex (MHC) molecules present antigens to T cells; MHC class I activates CD8 cells and MHC class II activates CD4 cells.
- π§ Immunodeficiency, such as AIDS caused by HIV, weakens the immune system by attacking CD4 cells.
- π€° The placenta acts as a barrier between mother and fetus, preventing maternal immune attack on the fetus.
- π©Έ Successful tissue or organ transplants require matching donor and recipient MHC and immunosuppressive therapy to prevent rejection.
Q & A
What is the main difference between humoral immunity and cell-mediated immunity?
-Humoral immunity, primarily mediated by B lymphocytes, defends the body against bacteria through the secretion of antibodies in the body's fluids, while cell-mediated immunity, primarily mediated by T lymphocytes, involves direct cell-to-cell interactions to destroy infected cells, such as those affected by viruses, fungi, or cancer.
What are the three types of cytokines mentioned in the script?
-The three types of cytokines mentioned are interleukins, colony-stimulating factors (CSF), and tumor necrosis factor (TNF).
How do antigen-presenting cells (APCs) interact with T lymphocytes?
-APCs interact with T lymphocytes by presenting antigens on their surface using major histocompatibility complex (MHC) molecules. MHC class I is used for activating CD8 T cells, while MHC class II is used for activating CD4 T cells.
What is the role of T helper cells in the immune response?
-T helper cells play a crucial role in activating other immune cells, such as B lymphocytes, to produce antibodies or become memory cells, enhancing the immune response to subsequent exposures to the same antigen.
How does the immune system distinguish between self and non-self?
-The immune system distinguishes between self and non-self through several mechanisms, including energy depletion to weaken potentially harmful self-reactive lymphocytes, deletion of strongly self-reactive T cells during maturation in the thymus, and the action of T regulatory cells that suppress self-reactive immunity.
What is the significance of the term 'humoral' in humoral immunity?
-The term 'humoral' in humoral immunity refers to the fact that antibodies are secreted into the body's fluids, such as serum or mucous membranes, to combat pathogens.
What is Acquired Immunodeficiency Syndrome (AIDS) and what causes it?
-AIDS is a syndrome characterized by a weakened immune system due to the infection with the Human Immunodeficiency Virus (HIV), which is an RNA virus. HIV-1 is the more common and global type, which primarily attacks CD4 helper T lymphocytes, impairing the immune system's ability to fight infections and diseases.
What is the role of Human Leukocyte Antigen G (HLA-G) in pregnancy?
-HLA-G, unique to pregnancy, is secreted by the placenta and helps prevent the mother's immune system from attacking the fetus by inducing a state of immunodeficiency that is protective for the survival of the fetus.
Why are live attenuated vaccines not recommended for pregnant women?
-Live attenuated vaccines are not recommended for pregnant women because their immune systems are already in a state of immunodeficiency to protect the fetus. The live microorganisms in these vaccines could pose a risk to both the mother and the developing baby.
What are the complications of hemolysis after a blood transfusion?
-Complications of hemolysis include hyperkalemia, hyperphosphatemia, and kidney damage due to the release of potassium, phosphate, and hemoglobin from burst red blood cells. Hemoglobin can also cause kidney failure and hemosiderin in the urine.
How can organ rejection after a transplant be prevented?
-Organ rejection can be prevented by matching the donor and recipient for blood and HLA types before surgery, and by using immunosuppressants after surgery to suppress the recipient's immune system and prevent it from attacking the transplanted organ.
Outlines
𧬠Cellular Immunity and T Cell Functions
This paragraph introduces the concept of cellular immunity, focusing on T lymphocytes' role in defending the body against viruses and fungi. It explains the difference between B lymphocytes, which produce antibodies to combat bacteria, and T lymphocytes. The explanation covers how antibodies neutralize antigens, the process of opsonization, agglutination, and activation of the complement system. It also delves into how immune cells communicate through cytokines, specifically interleukins, colony-stimulating factors, and tumor necrosis factors. The paragraph concludes with a review of immunology, detailing the process of antigen presentation, lymphocyte activation, and the development of memory cells for a faster and stronger immune response upon subsequent exposures to the same antigen.
π‘οΈ Major Histocompatibility Complex and Immune Activation
The second paragraph delves into the activation of T cells by antigen-presenting cells (APCs) through the Major Histocompatibility Complex (MHC). It discusses the importance of MHC class 1 and class 2 in activating CD8 and CD4 T cells, respectively. The paragraph also touches on the concept of signal one and signal two in T cell activation, involving interactions between CD80/86 and CD28. The explanation extends to the role of T helper cells in supporting the immune response and the function of T regulatory cells in preventing autoimmune reactions. Additionally, it covers the basics of Acquired Immunodeficiency Syndrome (AIDS), caused by the HIV virus, which targets CD4 helper T lymphocytes, leading to a weakened immune system.
π« Autoimmune Diseases and Transplant Rejection
This paragraph explores the mechanisms that prevent the immune system from attacking the body's own cells, such as energy depletion and deletion of self-reactive T cells during thymic maturation. It also explains the role of T regulatory cells in suppressing the immune system to avoid autoimmune diseases. The paragraph then discusses the complications of autoimmune diseases, including type 1 diabetes, myasthenia gravis, celiac disease, and rheumatoid lupus. Furthermore, it addresses the challenges of tissue transplants, such as organ rejection due to MHC incompatibility, and the measures taken to prevent it, including matching donors and recipients and using immunosuppressive drugs.
π©Έ Hemolysis and Its Complications
The final paragraph discusses the consequences of hemolysis, the rupture of red blood cells, which releases potassium, phosphate, and hemoglobin into the bloodstream. This can lead to hyperkalemia, hyperphosphatemia, and a decrease in calcium levels due to the solubility product relationship. The paragraph also explains how the accumulation of hemoglobin in the kidneys can cause kidney damage, leading to kidney failure and hemosiderinuria. It concludes with a reminder of the importance of blood screening to prevent the transmission of infections and a call to support the creator's educational efforts.
Mindmap
Keywords
π‘Cellular Immunity
π‘T Lymphocytes
π‘Antigens
π‘Cytokines
π‘Major Histocompatibility Complex (MHC)
π‘Acquired Immunodeficiency Syndrome (AIDS)
π‘Autoimmune Diseases
π‘T Regulatory Cells
π‘Human Leukocytic Antigen G (HLA-G)
π‘Organ Rejection
π‘Hemolysis
Highlights
Introduction to cellular immunity or T cell immunity, contrasting with B cell immunity.
Explanation of how plasma cells secrete antibodies, derived from B lymphocytes.
The process of neutralization, opsonization, agglutination, and activation of the complement system by antibodies.
Communication between immune cells via cytokines, categorized into interleukins, colony-stimulating factors, and tumor necrosis factor.
The role of T helper cells in activating B lymphocytes to produce antibodies or memory cells.
Differentiation between humoral immunity involving antibodies in body fluids and cell-mediated immunity involving direct cell-to-cell interaction.
Identification of T lymphocytes by their cluster of differentiation (CD) markers.
The function of T helper cells in supporting other immune cells and maintaining immune system balance.
The role of T cytotoxic cells in targeting virus-infected cells, fungi, and cancer cells.
Mechanisms of T cell activation involving antigen-presenting cells and MHC (Major Histocompatibility Complex).
Importance of the second signal in T cell activation, involving CD80/86 and CD28 interactions.
Definition and explanation of Acquired Immunodeficiency Syndrome (AIDS), its transmission routes, and the role of HIV.
The significance of the placenta in preventing maternal immune response against the fetus during pregnancy.
Overview of the mechanisms that prevent the immune system from attacking the body's own cells.
Discussion on autoimmune diseases, such as type 1 diabetes, myasthenia gravis, and celiac disease, caused by the immune system attacking self-antigens.
Importance of matching donors and recipients in organ transplants to prevent immune rejection.
Strategies to prevent organ rejection, including immunosuppressive drugs and total lymphoid irradiation.
The process of blood transfusion compatibility and the risks associated with incompatible blood types.
Complications of hemolysis, including hyperkalemia, hyperphosphatemia, and kidney damage.
Historical context on blood transfusion methods and advancements in preventing air embolism.
Call to action for viewers to support the channel and access additional educational resources.
Transcripts
what's going on everybody is medicosis
perfectionist where medicine makes
perfect sense let's continue our
physiology playlist in the last video we
talked about the hemorrhagial immunity
or the b cell immunity today it's time
to talk about the cell mediated or
cellular immunity or t cell immunity b
lymphocytes mainly defend your body
against bacteria but t lymphocytes
defend your body against viruses and
fungi joe rogan may relate now let's get
started who secretes antibodies plasma
cells where did they come from from b
lymphocytes what happens when your
antibody meets the foreign antigen
neutralization of the bad antigen
opsinization make it tasty agglutination
activation of the natural killer cell to
kill those bacteria and activation of
the complement system remember the
antigen antibody complex activates the
classical pathway of the complement we
have three complement pathways number
one the classical pathway number two
alternative pathway number three mannose
binding lectin pathway how do your
immune cells such as the lymphocytes
communicate with each other they release
cytokines what does cyto mean cell
because they are talking to each other
and they are cells kinds from kinetic
motion oh some secreting chemicals to
put these cells in motion love it here
is the most basic idea of cytokines they
are divided into three categories
the interleukins colony stimulating
factors and tumor necrosis factor ilcsf
tnf what does inter mean between look
leukocytes or white blood cells i n is a
protein or peptide or whatever so
interleukin literally means the internet
of the leukocytes i love it this is how
they communicate with each other colony
stimulating factors factors that
stimulate the colony of the white blood
cells for example and if you remember my
previous videos we talked about gcsf and
gm csf granulocyte colony stimulating
factor and granulocyte monocyte colony
stimulating factor let's review the
story of immunology here is a foreign
bacteria invading your body we'll take a
piece of it the piece is called the
antigen and then who's gonna present the
antigen antigen presenting cells duh
presented to whom to the lymphocytes and
when the lymphocytes recognize the
antigen they will stop being so naive
and they will grow the french toast up
grow to do what to destroy the microbe t
lymphocytes especially the t helper
cells are going to activate the b
lymphocytes so that the b lymphocytes
become plasma cells to secrete
antibodies or to become memory cells so
that we can remember this interaction so
that the second exposure to the same
antigen is gonna be faster and stronger
we're gonna kick that bacteria in the
butt as you know the antigen presenting
cells could be a macrophage a v
lymphocytes or a dendritic cell b
lymphocytes hemorrhal immunity t
lymphocytes cell mediated immunity why
do you call this femoral immunity
because we're secreting antibodies in
the humors the fluids of the body such
as the serum or your mucous membrane
fluid why do you call this cell mediated
because the cell by itself is gonna go
and kill this stupid virus face to face
cell to cell that's why it is cell
mediated the t lymphocytes could be t
helper cd4 or t cytotoxic cd8 the
cluster of differentiation is like your
identification card how does the police
recognize adam by his id okay how do you
recognize the type of the lymphocytes by
their cd the t toxic side to toxic toxic
to cells i'm toxic to fungi virus
infected cells and cancer cells but t
helper is of huge help i can help my
sister i can help my brother i can help
my neighbor okay tell me about your
sister the t-shirt toxic i am cd4 she's
cd8 she's my sister we're very close
both of us have cd3 as well okay why
would you help the t-cell toxic to kill
foreigners and cancers how do you help
your brother i help the t regulatory
cell formerly the t suppressor cell
suppress my own immunity a little bit so
that i do not attack my own cells so
that i gain tolerance to the self
otherwise i will get autoimmune diseases
how do you help your neighbor i will
help my neighbor the bay lymphocyte to
mature and grow the french toast up so
that it can become memory cell to
remember the same bacteria when she
comes again next time or to become
plasma cells to secrete antibodies into
the fluids of my body let's activate the
t cell what's that the antigen
presenting cell presenting what the
antigen or the food to the t lymphocyte
and what's the tray on which you put the
food mhc okay
if we are activating
cd8 we will use mhc class 1 but if we
are activating cd4 t lymphocytes we will
use mhc2 so that the product is always
8. mhc class 1
will activate cd8 t cells and mhc class
2 will activate cd4 cells the result is
8. okay so now i know that the mhc major
histocompatibility complex will interact
with the t cell receptor which is a
receptor on the t lymphocyte imagine my
shock but why did we call it major
histocompatibility complex major because
it's a major group of proteins and there
is another group called minor complex
because it's more than one protein
histocompatible i love it compatible
with my own tissue and that's why when i
saw the bacteria this was not compatible
oh it's about compatibility then you got
it what's that this is the id of the
lymphocyte i could be cd4 or cd8 whether
i'm cd4 or cd8 i'll also have the cd3 id
this is the first signal the second
signal is cd 8086 from the antigen
presenting cell with cd 28 from the t
lymphocyte everything here is eight 80
86 28. they will interact together so
here is signal number one and here is
signal number two that's why we call
this signal and co signal or co
stimulation
cd8086 has another name b7 protein why
b7 the way i remember it is that the
antigen presenting cell could be a b
lymphocyte right yeah it's easy to
remember 7 28 8086 what is acquired
immunodeficiency syndrome or aids it's a
syndrome which means more than one
symptom affecting the same person
immunodeficiency my immune system is
weak deficient acquired because it's not
inherited it's not congenital i'm not
born with it most of the time i acquire
it later in life whether it is through
inner course parental transmission by
injections vertical transmission from
mommy to baby while passing through the
vaginal canal during delivery or from
mommy to baby via breastfeeding this is
the name of the disease and i've just
told you about the route of transmission
but what's the cause oh the infectious
particle is hiv virus which is an rna
virus there are two types of this or two
major types hiv-1 and hiv2 which one is
more common hiv-1 which one is more
global
hiv-1 it's gonna attack my cd4
helper t lymphocytes and therefore i
cannot help my sister and i cannot help
my neighbor i cannot kill virus
virus-infected cells and i cannot
secrete antibodies that's why my
immunity is frail another important
point mom is different from the baby
their genetic material is different and
they are immunologically different and
that's why the placenta is so important
the placenta acts as a barrier between
the mother and the fetus to prevent the
mixing of blood between the maternal and
the fetal sides and in order for mommy
not to attack her baby the pregnancy
will induce a state of
immunodeficiency which is protective for
the survival of the fetus that's why we
do not give pregnant women live
attenuated vaccines because their
immunity is already weak and live
attenuated vaccines contain the live
microorganism or the life agent this
could be dangerous during pregnancy
moreover the placenta secretes human
leukocytic antigen g have you ever heard
of g no i've heard of hla a b c which
are part of mhc1 and hlad which is part
of mhc2 i've never heard of hlag yup
this is unique to pregnancy and g stands
for gestation do you want your immune
system to attack and destroy foreign
invaders abso freaking lootly do you
want your immune system to attack your
own cells oh heck no if my immune system
attacks my own cells i will get an
autoimmune disease which is horrible
then how come normally speaking your
immune system does not attack your own
cells how did the immune system tell the
difference between the self and the
non-self jazillion mechanisms i'll just
give you three number one colonel energy
those two lymphocytes that might get
crazy and attack my own cells will just
make them weak will weaken them and no
energy from energy like no energy all
the t lymphocytes will be stupid and
lazy so that they do not attack my own
antigens how about the one that are
super strong against my own cells delete
them destroy them wipe them out where
did the t lymphocyte mature in the
thymus okay i will destroy it there also
the t regulatory cells formally t
suppressor cells will suppress my own
immunity just a little now what if i
fail to do all of this your immune
system is gonna attack your own cells
creating auto antibodies and this is
called an autoimmune disease such as
type 1 diabetes where you have
antibodies attacking your own pancreas
especially the beta cells which make
insulin myasthenia gravis you have
antibodies attacking your own nicotinic
sub m receptor on the skeletal muscle
that's why these patients are weak we
also have celiac disease which is auto
antibodies against tissue
transglutaminase iga in the small
intestine
rheumatoid lupus and others there are
other topics that you need to know when
it comes to the physiology of the blood
and the immune system and this is the
incompatibility and the rh
incompatibility they were discussed in
great detail in my hematology playlist
right here on youtube let's talk about
tissue transplant okay here is adam's
kidney right adam is donating a kidney
to sarah because sarah needs a kidney as
you might have noticed adam is different
from sarah well no duh adam has a
different mhc than sarah yeah its major
h2 compatibility of course was
compatible with adam might not be the
same as what's compatible with sarah
thank you captain obvious can this be a
problem absolutely adam gave his kidney
to sarah but sarah recognized the kidney
as foreign to her and started attacking
the kidney and destroying the kidney
after the transplant surgery i don't
recognize this kidney this is just some
caring behavior right there hey
mithicosis why are you attacking
patients so much why don't you have some
respect for yourself yes ma'am i was
just joking so how do we prevent this
how do we prevent this organ rejection
well before surgery we have to do some
stuff and after surgery we have to do
some stuff before surgery match the
donor with the recipient how do i do it
groups make sure they match our age
groups make sure that they match and hla
matching and then you prepare the
patient by suppressing the patient's
immunity so that the patient's immune
system does not attack the new kidney
and immunosuppressants include
glucocorticoids or steroids cyclosporine
cyrolimus tacrolimus
antithymocyte globulins etc if it is so
severe total lymphoid irradiation we
will destroy sarah's lymphoid organs so
that they do not secrete crazy
lymphocytes that attack the new kidney
these medications are not the same they
have different indications different
side effects etc and this was discussed
in my course called anti-cancer
pharmacology available to download on my
website medicosisperfectsnation.com
blood
same concept applies before you give
blood from a donor to a recipient match
them make sure they are compatible with
each other because if they are not
compatible bad things can happen antigen
antibody reaction destroying the red
blood cell too it's gonna rupture
causing hemolysis and hemolytic anemia
also these complexes can clog vessels
causing ischemia and pain historically
before we used plastic bags for blood we
used to use glass bottles the blood will
run out and then air bubbles will go
from the bottle to the patient's blood
causing air embolism but now the plastic
bags they will just recoil after the
last drop of blood preventing air
embolism this is huge if you gave the
patient some dirty blood you might
introduce infections that's why before
you give any blood you need to screen it
make sure that it's healthy and clean
and does not contain hiv hepatitis b
hepatitis c and others back to hemolysis
what are the complications of hemolysis
remember that this is a red blood cell
right red blood cell so like any cell it
has lots of potassium because potassium
is more abundant intracellularly than
extracellularly it has phosphate
remember atp
and the membrane has what
phospholipid okay and hemoglobin that's
in the red blood cell so when the red
blood cell bursts it will release tons
of potassium and phosphate and
hemoglobin into the blood causing
hyperkalemia hyperphosphatemia
phosphate and calcium like hate each
other there is an inverse relationship
between them we call this the solubility
product so whenever phosphate goes up
usually calcium goes down hemoglobin
lots of hemoglobin in the blood is
called hemoglobin anemia eventually it's
going to end up in the kidney hemoglobin
area hemoglobin can destroy your kidney
kidney failure and hemosiderin auria
cetera means iron as you know hemoglobin
is made of heme and globin and the heme
is made of iron and protoporphyrin these
two doofuses are toxic to the kidney if
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