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MBBCh 2- HAEM2000A > F. Immunology (2) > Flashcards

F. Immunology (2) Flashcards

1
Q

B-cell functioning:

Naive B cells, with their unique BCRs, circulate in the peripheral blood and lymph nodes.

How does this process work? (3)

A
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2
Q

B-cell functioning:

● Activation of the B cell occurs when an effector T follicular helper (TFH) cell, which carries a T cell receptor (TCR) that recognizes the peptide-MHCII complex, binds to the B cell.

How does this process work? (3)

A
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3
Q

B-cell functioning:

● Activation of the B cell occurs when an effector T follicular helper (TFH) cell, which carries a T cell receptor (TCR) that recognizes the peptide-MHCII complex, binds to the B cell.

How does this process work? (3)

A
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4
Q

How is the diversity of the BCR repertoire achieved?

A

● The diversity of the BCR repertoire is achieved through various mechanisms, including combinatorial diversity (VDJ and VJ gene segments), junctional diversity (nucleotide addition between gene segments), combination of heavy and light chain proteins, and somatic hypermutation.

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5
Q

What is somatic hypermutation?

A

● Somatic hypermutation occurs when an enzyme activated by the effector TFH cell introduces point mutations in the variable region of the BCR gene. If the BCR produced has an increased affinity for the pathogen, the B cell continues to proliferate. If the affinity decreases, the B cell undergoes apoptosis.

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6
Q

What is the paratope?

A

● The antigen binding site, also known as the paratope, is a specific region on an antibody molecule that is responsible for binding to antigens. It is located at the tips of the variable regions of both the heavy and light chains.

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7
Q

● The heavy chain of an antibody molecule consists of both a constant region and a _____ region.

A

variable

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8
Q

What does the heavy chain determine?

A

● The heavy chain constant region determines the antibody’s isotype or class (e.g., IgG, IgM, IgA), while the heavy chain variable region is responsible for antigen binding and contains the antigen binding site.

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9
Q

● Similarly, the light chain of an antibody molecule also consists of a constant region and a variable region.
􏰁 The light chain can be either a ____ (κ) chain or a ______ (λ) chain.
􏰁 The light chain variable region, like the heavy chain variable region, is involved in antigen
_______.

A

kappa
lambda
binding

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9
Q

● Similarly, the light chain of an antibody molecule also consists of a constant region and a variable region.
􏰁 The light chain can be either a ____ (κ) chain or a ______ (λ) chain.
􏰁 The light chain variable region, like the heavy chain variable region, is involved in antigen
_______.

A

kappa
lambda
binding

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10
Q

● The overall structure of an antibody molecule consists of ____ heavy chains and ___ light
chains, forming a Y-shaped structure.

􏰁 The antigen binding sites are located at the tips of the Y, where the variable regions of the
heavy and light chains come together to form a _____ _______.

A

two
two
binding pocket

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11
Q

● When an antibody molecule is cleaved with the enzyme papain, it results in…

A

● When an antibody molecule is cleaved with the enzyme papain, it results in the formation of two Fab fragments and one Fc fragment.

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12
Q

What are Fab fragments?

A

􏰁 The Fab fragments, also known as fragment antigen binding, contain the variable
regions of both the heavy and light chains and retain the antigen binding site.

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13
Q

What are Fc fragments? (2)

A

􏰁 The Fc fragment, or fragment constant, consists of the constant regions of the heavy
chains and is responsible for the antibody’s effector functions.

􏰁 The Fc region of an antibody molecule can bind to various molecules or cells.

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14
Q

What is the function of the antibodies? (5)

A
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15
Q

● There are five main classes of antibodies:

A
  1. IgM
  2. IgD
  3. IgG
  4. IgA
  5. IgE
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16
Q
  1. IgM:
    What is the function? (4)
A

✔ IgM is the first antibody produced during an infection.
✔ It exists as a pentamer, meaning it consists of five antibody molecules joined together.
✔ IgM has a low affinity for antigens because it has not undergone somatic
hypermutation, but it compensates for this with its ten antigen-binding sites, which contribute to high avidity.
✔ IgM can fix complement and act as an opsonin.

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17
Q
  1. IgD:
    What is the function? (3)
A

✔ The B cell heavy chain gene transcribes both the Cμ (constant region μ) and Cδ (constant region δ) genes.
✔ Through alternative splicing, either IgM or IgD is produced.
✔ IgD is expressed on the surface of B cells along with IgM, but its function is not fully understood. It may play a role in B cell activation and can bind to basophils and mast cells.

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18
Q
  1. IgG:
    What is the function? (3)
A

✔ IgG is the most abundant antibody in the blood and the most important antibody in
tissues.
✔ It is a monomer and can fix complement. IgG can cross the placenta, providing
passive immunity to the fetus.
✔ The Fc region of IgG is recognized by Fcγ receptors on various immune cells, such as
macrophages, neutrophils, dendritic cells, and natural killer cells.

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19
Q
  1. IgA:
    What is the function? (4)
A

✔ IgA exists as a dimer, meaning it consists of two antibody molecules joined together.
✔ It is primarily involved in mucosal immunity.
✔ IgA acts as a neutralizing antibody on luminal surfaces. It is synthesized by plasma
cells in MALT.
✔ IgA is secreted in breast milk, providing passive immunity to newborns.

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20
Q
  1. IgE:
    What is the function? (4)
A

✔ IgE is a monomeric antibody that plays a role in allergic reactions and antiparasitic defense.
✔ It binds to Fcε receptors on mast cells and basophils.
✔ Upon second exposure to an antigen, IgE can cross-link on the surface of mast cells,
leading to mast cell degranulation and the release of inflammatory mediators.
✔ IgE is involved in allergies and has a role in defending against parasites.

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21
Q
  1. IgE:
    What is the function? (4)
A

✔ IgE is a monomeric antibody that plays a role in allergic reactions and antiparasitic defense.
✔ It binds to Fcε receptors on mast cells and basophils.
✔ Upon second exposure to an antigen, IgE can cross-link on the surface of mast cells,
leading to mast cell degranulation and the release of inflammatory mediators.
✔ IgE is involved in allergies and has a role in defending against parasites.

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22
Q

What is monoclonal antibodies? (2)

A

● Monoclonal antibodies are highly specific antibodies that are derived from a single clone of cells, producing identical copies of a particular antibody molecule.

● Each antibody recognizes a unique part of a target molecule called an epitope. Since each antigen can have multiple epitopes, it can be recognized by different antibodies.

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23
Q

● Monoclonal antibodies can be designed to specifically target and _____ harmful molecules or cells involved in disease processes. They can _______ the immune response, deliver drugs to specific sites, or interfere with molecular pathways, offering potential treatments with high specificity and fewer side effects compared to traditional ______.

A

block
modulate
drugs

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24
Q

● Monoclonal antibodies can be designed to specifically target and _____ harmful molecules or cells involved in disease processes. They can _______ the immune response, deliver drugs to specific sites, or interfere with molecular pathways, offering potential treatments with high specificity and fewer side effects compared to traditional ______.

A

block
modulate
drugs

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25
Q

● The production of monoclonal antibodies involves a process known as hybridoma technology.

What is the process? (8)

A
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26
Q

What happens after the selection of hybridomas?

Several additional steps are involved in the production of monoclonal antibodies: (5)

A
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27
Q

What happens after the selection of hybridomas?

Several additional steps are involved in the production of monoclonal antibodies: (5)

A
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28
Q

● The selection of Fab (Fragment antigen-binding) by using bacteriophages and then producing the antibodies in bacteria or cell lines is a method used to generate recombinant immunoglobulins, including monoclonal antibodies, in large quantities efficiently.

What is this process? (9)

A
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29
Q

Monoclonal antibodies functions: (7)

A
  1. Production in large quantities
  2. Identifying specific antigens
  3. Molecular biology tool
  4. Monoclonal antibodies have also found extensive applications in medicine.
  5. Targeting cell surfaces
  6. Receptor modulation
  7. Drug delivery
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30
Q

Monoclonal antibodies functions
1. Production in large quantities:

A

Monoclonal antibodies can be produced in large quantities as the hybridoma clone used to generate them is immortal. This ensures a consistent and ample supply for experimental purposes.

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31
Q

Monoclonal antibodies functions
2. Identifying specific antigens:

A

Monoclonal antibodies enable accurate identification of specific antigens, including specific epitopes on antigens. This specificity is crucial in research, diagnostics, and characterization of molecules or cells.

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32
Q

Monoclonal antibodies functions
3. Molecular biology tool:

A

Monoclonal antibodies have become fundamental tools in molecular biology science. They are employed in techniques such as immunoprecipitation, immunofluorescence, Western blotting, and immunohistochemistry, enabling the detection and analysis of proteins in various biological samples.

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33
Q

Monoclonal antibodies functions
4. Monoclonal antibodies have also found extensive applications in medicine:

A

They can be used as therapeutic drugs to target specific antigens and modulate biological processes.

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34
Q

Monoclonal antibodies functions
5. Targeting cell surfaces:

A

Monoclonal antibodies can bind to antigens on cell surfaces, leading to cell death by activating the immune system or inhibiting specific signaling pathways.

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35
Q

Monoclonal antibodies functions
6. Receptor modulation:

A

Monoclonal antibodies can activate or inhibit specific receptors to modulate cellular functions. They can enhance immune responses or block the binding of ligands to receptors, interfering with disease processes.

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36
Q

Monoclonal antibodies functions
7. Drug delivery:

A

Monoclonal antibodies can be utilized. to deliver drugs or radiation specifically to target cells or tissues, minimizing off-target effects and increasing therapeutic efficacy.

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37
Q

● Some examples of monoclonal antibodies used as drugs include:

A
38
Q

● Some examples of monoclonal antibodies used as drugs include:

A
39
Q

What is a T cell receptor? (2)

A

● A TCR, or T cell receptor, is a protein complex found on the surface of T cells, which are a type of white blood cell involved in the immune response.

● The TCR is responsible for recognizing and binding to specific antigens, such as proteins or peptides, presented by major histocompatibility complex (MHC) molecules on the surface of other cells.

40
Q

● The TCR is composed of two chains called the _______ and _____ chains.
􏰁 Each chain has a variable region and a _____ region.
􏰁 The variable regions of the alpha and beta chains are responsible for antigen recognition, while the constant regions provide structural stability to the TCR ______.

A

ALPHA
BETA
CONSTANT
COMPLEX

41
Q

● The diversity of TCRs is crucial for the immune system’s ability to recognize a wide range of antigens.
􏰁 The generation of TCR diversity occurs during T cell development in the ______.
􏰁 It involves the _______ of gene segments in the variable region of the alpha and beta chain genes.
􏰁 This recombination process is known as ____ recombination.

A

thymus
recombination
VDJ

42
Q

What happens In the alpha chain gene?

A
43
Q

What happens In the alpha chain gene?

A
44
Q

What happens in the beta chain gene? (2)

A
44
Q

What happens in the beta chain gene? (2)

A
45
Q

􏰁 The recombined genes are transcribed into pre-_____, which is further processed to mature mRNA and translated into protein. The alpha and beta chains produced by this process then join together to form a ______ TCR complex.

A

mRNA
functional

46
Q

􏰁 In the thymus, T cells undergo positive and negative selection to ensure their functionality and self-tolerance.

What happens in the thymus? (3)

A
47
Q

􏰁 Negative selection takes place in the thymic medulla. What does this mean? (2)

A
48
Q

What happens after CD8 T cells mature in the thymus? (2)

A

● After maturation in the thymus, naïve CD8 and CD4 T cells, which express the co-receptors CD8 and CD4 respectively, leave the thymus and circulate between the blood and peripheral lymphoid tissues (such as lymph nodes and spleen).

● In secondary lymphoid organs, such as lymph nodes, they encounter mature dendritic cells, which are specialized antigen-presenting cells.

49
Q

● When a naïve CD8 T cell encounters a mature dendritic cell presenting an antigen on MHC class I molecules (MHCI), it undergoes activation.

What happens when activation happens? (2)

A

􏰁 This activation involves the recognition of the antigen-MHCI complex by the T cell receptor (TCR) on the CD8 T cell.

􏰁 If the TCR recognizes the antigen as non-self (foreign), the CD8 T cell survives and becomes an effector CD8 T cell.

50
Q

● When a naïve CD8 T cell encounters a mature dendritic cell presenting an antigen on MHC class I molecules (MHCI), it undergoes activation.

What happens when activation happens? (2)

A

􏰁 This activation involves the recognition of the antigen-MHCI complex by the T cell receptor (TCR) on the CD8 T cell.

􏰁 If the TCR recognizes the antigen as non-self (foreign), the CD8 T cell survives and becomes an effector CD8 T cell.

51
Q

What is the function of effector CD8 T cells? (2)

A

✔ They recognize virus-infected cells or cells harboring intracellular bacteria by binding to antigen peptides presented on MHCI molecules on the surface of these infected cells.

✔ The binding of the effector CD8 T cell to the infected cell triggers various mechanisms to eliminate the infected cell.

52
Q

What is the function of effector CD8 T cells? (2)

A

✔ They recognize virus-infected cells or cells harboring intracellular bacteria by binding to antigen peptides presented on MHCI molecules on the surface of these infected cells.

✔ The binding of the effector CD8 T cell to the infected cell triggers various mechanisms to eliminate the infected cell.

53
Q

􏰁 One mechanism is the secretion of _______, such as interleukin-2 (IL-2), by the activated CD8 T cell.

✔ __-___ stimulates the proliferation and activation of other immune cells, including CD8 T cells themselves, leading to an amplified immune response against the infection.

A

cytokines
IL-2

54
Q

✔ Additionally, the effector CD8 T cell can induce apoptosis (programmed cell death) in the infected cell through two pathways:

A
  1. Extrinsic pathway
  2. Perforin and granzyme pathway
55
Q

What is the extrinsic pathway in terms of CD8 cells?

A

The CD8 T cell binds death ligands to death receptors on the infected cell, initiating a cascade of signals that ultimately trigger apoptosis.

56
Q

What is the Perforin and granzyme pathway in terms of CD8 cells?

A

The CD8 Tcell releases perforin,a protein that creates pores in the membrane of the infected cell. Through these pores, the effector CD8 T cell delivers granzymes, which are proteases that induce cell death within the infected cell.

57
Q

􏰁 Once activated, the effector CD8 T cell can exit the lymphoid organ through efferent lymph vessels and enter the bloodstream.

What happens next? (2)

A

✔ It can then migrate to the site of infection, where it carries out its functions to eliminate infected cells.

✔ Some of the activated CD8 T cells also differentiate into memory CD8 T cells, which provide long-lasting immunity against future encounters with the same pathogen.

58
Q

What is the function of CD4 T cells? (2)

A

● Effector CD4 T cells, also known as helper T cells, do not possess cytotoxic or phagocytic activity.

● Instead, their main function is to mediate the immune response by directing other cells to perform tasks and regulating the type of immune response that develops. This is
achieved through direct interactions with other immune cells or by secreting cytokines, which are signalling molecules that influence the behavior of nearby cells.

59
Q

● Upon leaving the thymus as mature naïve CD4 T cells, these cells circulate in the blood and peripheral lymphoid tissues.

What happens next? (3)

A
60
Q

● Upon leaving the thymus as mature naïve CD4 T cells, these cells circulate in the blood and peripheral lymphoid tissues.

What happens next? (3)

A
61
Q

􏰁 Several subsets of effector CD4 T cells have been identified, each with distinct functions and cytokine profiles:

A
62
Q

● The Major Histocompatibility Complex (MHC) proteins are a set of cell surface proteins that play a crucial role in the immune system.

What are they responsible for?

A

􏰁 They are responsible for presenting peptide fragments derived from intracellular or extracellular pathogens to the T cell receptor (TCR) of T cells.

63
Q

􏰁 MHC proteins are highly ________, meaning they exhibit a high degree of genetic variation among individuals. This polymorphism is a primary cause of _____ _______ in
transplantation, as the recipient’s immune system may recognize the foreign MHC proteins as non-self and mount an immune response against them.

A

pol

64
Q

What is Histocompatibility?

A

􏰁 Histocompatibility, which refers to the compatibility of tissues or organs between individuals, needs to be determined before transplantation to minimize the risk of rejection. This is typically done by matching the MHC types of the donor and recipient to ensure compatibility and reduce the likelihood of an immune response against the transplanted tissue or organ.

65
Q

● When it comes to the activation of naive CD8 T cells by the innate immune system, mature dendritic cells play a crucial role.

What role do they play? (3)

A

􏰁 Dendritic cells are specialized antigen-presenting cells that capture antigens from pathogens and present them to T cells.

􏰁 In the case of CD8 T cells, mature dendritic cells present peptides derived from cytoplasmic pathogens that are attached to MHC class I (MHCI) proteins to the TCR of naive CD8 T cells.

􏰁 This interaction triggers the activation of naive CD8 T cells, leading to their differentiation into effector CD8 T cells, which play a central role in eliminating infected cells.

66
Q

● To determine if cells in the body are infected, the adaptive immune system relies on the T cell receptors (TCRs) of effector CD8 T cells.

What do these TCRs monitor?

A

􏰁 These TCRs monitor the peptides presented on MHC class I (MHCI) proteins on the surface of cells.

67
Q

● To determine if cells in the body are infected, the adaptive immune system relies on the T cell receptors (TCRs) of effector CD8 T cells.

What do these TCRs monitor?

A

􏰁 These TCRs monitor the peptides presented on MHC class I (MHCI) proteins on the surface of cells.

68
Q

􏰁 Almost all ______ cells in the body, with the exception of red blood cells (RBCs), express MHCI molecules.
􏰁 When a cell becomes infected with a pathogen, it processes intracellular proteins, including viral proteins, into ____ ______. These peptides bind to the MHCI molecules within the cell and are presented on the cell surface.
􏰁 The effector CD8 T cells, with their______ specialized in recognizing specific peptides, can then recognize the infected cells displaying these peptides on their MHCI molecules. This recognition triggers an immune response, leading to the elimination of the infected cells.
􏰁 In humans, the MHCI proteins are ______ by the Human Leukocyte Antigen (HLA) genes.

A

nucleated
peptide fragments
TCRs
encoded

69
Q

􏰁 Almost all ______ cells in the body, with the exception of red blood cells (RBCs), express MHCI molecules.
􏰁 When a cell becomes infected with a pathogen, it processes intracellular proteins, including viral proteins, into ____ ______. These peptides bind to the MHCI molecules within the cell and are presented on the cell surface.
􏰁 The effector CD8 T cells, with their______ specialized in recognizing specific peptides, can then recognize the infected cells displaying these peptides on their MHCI molecules. This recognition triggers an immune response, leading to the elimination of the infected cells.
􏰁 In humans, the MHCI proteins are ______ by the Human Leukocyte Antigen (HLA) genes.

A

nucleated
peptide fragments
TCRs
encoded

70
Q

􏰁 Each individual expresses three different MHCI molecules: (3)

A

HLA-A, HLA-B, and HLA-C.

71
Q

􏰁 Each individual expresses three different MHCI molecules: HLA-A, HLA-B, and HLA-C.
✔ These molecules are __________ expressed, meaning both copies of the genes on the two chromosomes contribute to the expression of MHCI proteins.
✔ As a result, each person has many thousands of copies of each of the six MHCI molecules (HLA-A, HLA-B, and HLA-C) in their cells, increasing the _______ of peptides that can be presented and recognized by T cells.

A

codominantly
diversity

72
Q

What do the HLA genes encode for?

A

● The HLA-A, HLA-B, and HLA-C genes, which encode the major histocompatibility complex (MHC) class I proteins, are highly polymorphic. This means that there are hundreds of
different alleles or variants of these genes in the human population. However, each individual has only two alleles of each gene unless they are homozygous for a particular allele.

73
Q

The polymorphic nature of the HLA genes results in…

A

significant genetic diversity within the population. Most people are heterozygous, meaning they carry two different allelic forms of
each MHC locus (HLA-A, -B, and -C). The key differences between these allelic forms lie in the specific amino acids present in the peptide interaction sites of the MHC proteins.

74
Q

● These amino acid differences in the peptide interaction sites lead to variations in the binding ________ of the MHC molecules. Different MHC variants have a higher affinity for binding to specific peptides derived from pathogens or cellular proteins. As a result, the ____ ___ _______ that can bind to MHC molecules is increased due to this polymorphism.

● Certain HLA alleles have been associated with an increased risk or ________ against specific diseases. For example, the HLA-B27 allele is strongly associated with ankylosing spondylitis, a type of inflammatory arthritis that primarily affects the spine. On the other hand, certain HLA alleles, such as ____-______, have been associated with resistance or recovery from certain diseases, such as lethal ______.

A

preferences
range of peptides
protection
HLA-B53
malaria

75
Q

● In the innate immune system, the activation of naive CD4 T cells of the adaptive immune system occurs through the presentation of antigens by mature dendritic cells.

What is the full process? (9)

A
76
Q

● Effector CD4 T cells that recognize antigens presented by MHCII molecules expressed on macrophages can ______ macrophages to enhance their phagocytic and microbicidal activities. This activation leads to a more efficient _______ of pathogens.

A

stimulate
clearance

77
Q

● In the case of B cells, effector CD4 T cells can provide help in the form of cytokines and direct cell-to-cell interactions. This help is crucial for …

A

B cell activation, proliferation, and differentiation into antibody-producing plasma cells. The interaction between effector CD4 T cells and B cells is essential for the production of high-affinity antibodies and the establishment of immunological memory.

78
Q

How do Effector CD4 T cells influence the activity of dendritic cells?

A

● Effector CD4 T cells can also influence the activity of dendritic cells. By recognizing antigens presented by MHCII molecules on dendritic cells, CD4 T cells can provide positive signals for dendritic cell activation, leading to enhanced antigen presentation and T cell priming. This interaction is crucial for the initiation and regulation of adaptive immune responses.

79
Q

● MHCII molecules are composed of alpha (α) and beta (β) chains, and in humans, they are called…

A

HLA-DP, HLA-DQ, or HLA-DR. Peptides binding to MHCII molecules are typically longer than those binding to MHCI and are usually greater than 13 amino acids in length. Multiple different peptides can bind to a single MHCII molecule, broadening the range of antigens that can be presented to CD4 T cells.

80
Q

Antigens for MHC II

● Processing of antigens for MHCII presentation involves several steps:

A

􏰁 Antigen Uptake
􏰁 Antigen Degradation
􏰁 MHCII Protein Production
􏰁 Targeting to Endosome
􏰁 Removal of Invariant Chain
􏰁 Peptide Exchange
􏰁 Fusion with Cell Membrane
􏰁 TCR Recognition

80
Q

Antigens for MHC II

● Processing of antigens for MHCII presentation involves several steps:

A

􏰁 Antigen Uptake
􏰁 Antigen Degradation
􏰁 MHCII Protein Production
􏰁 Targeting to Endosome
􏰁 Removal of Invariant Chain
􏰁 Peptide Exchange
􏰁 Fusion with Cell Membrane
􏰁 TCR Recognition

81
Q

Antigens for MHC II
􏰁 Antigen Uptake:

A

Dendritic cells and macrophages phagocytose extracellular pathogens or antigenic material, forming a phagosome. B cells, on the other hand, endocytose pathogens bound to their B cell receptor (BCR), forming an endosome.

82
Q

Antigens for MHC II
􏰁 Antigen Degradation:

A

Within the phagosome or endosome, pathogen proteins are degraded by acid proteases, resulting in the generation of peptide fragments. These peptide fragments are derived from the antigens encountered by the antigen-presenting cell (APC).

83
Q

Antigens for MHC II
􏰁 MHCII Protein Production:

A

The MHCII proteins are synthesized in the endoplasmic reticulum (ER) of the APC. During this process, an invariant chain binds to the MHCII molecule, preventing peptides imported into the ER from binding to the peptide-binding cleft of MHCII.

84
Q

Antigens for MHC II
􏰁 Targeting to Endosome:

A

The invariant chain not only blocks peptide binding but also guides the MHCII molecule to fuse with an endosome containing the peptide fragments derived from the pathogen.

85
Q

Antigens for MHC II
􏰁 Removal of Invariant Chain:

A

Within the endosome, acid proteases cleave the invariant chain, except for a small fragment called CLIP (class II-associated invariant chain peptide). CLIP remains bound to the peptide-binding groove of MHCII, blocking the binding of other peptides.

86
Q

Antigens for MHC II
􏰁 Peptide Exchange:

A

HLA-DM, a protein present within the endosome, facilitates the exchange of CLIP with pathogen-derived peptides. HLA-DM helps to select and stabilize high-affinity peptides, ensuring optimal peptide binding to MHCII.

87
Q

Antigens for MHC II:
􏰁 Fusion with Cell Membrane:

A

The vesicle containing MHCII molecules, each bound to a specific peptide fragment, fuses with the cell membrane of the APC.

88
Q

Antigens for MHC II:
􏰁 Fusion with Cell Membrane:

A

The vesicle containing MHCII molecules, each bound to a specific peptide fragment, fuses with the cell membrane of the APC.

89
Q

Antigens for MHC II:
􏰁 TCR Recognition:

A

The MHCII molecules on the cell surface present the attached peptide fragments to the T cell receptor (TCR) of CD4 T cells. CD4 T cells, which express the CD4 co-receptor, recognize the antigenic peptide-MHCII complex through their TCR.

90
Q

● In humans, each antigen-presenting cell (APC) expresses three different MHCII molecules:

A
91
Q

● In humans, each antigen-presenting cell (APC) expresses three different MHCII molecules:

A

MBBCh 2- HAEM2000A (30 decks)

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