Immunity-Chapter 5 Flashcards
Cell Mediated Immunity is carried out primarily by which types of cell?
T-Cells
T cells defend against intracellular or extracellular microbes
Intracellular microbes
What are some of the functions of CD4+ helper cells
- Help B cells produce antibodies
- Defense against microbes
- Promote inflammatory response
- Activation of phagocytes
True or False. Naïve T lymphocytes recognize antigens in the peripheral lymphoid organs which stimulates their proliferation and differentiation into effector and memory cells
True
What are the steps in the activation of T lymphocytes?
- Antigen presentation and recognition to naïve T cell (CD4+ or CD8+)
- Activation which involves secretion of cytokines
- Clonal expansion
- Differentiation into effector T cells (CD4+ helper or CD8+ CTL and Memory T cells (CD4+ or CD8+
How do memory T-cells develop
Progeny of the T cells that have proliferated in response to antigen develop into T memory cells
True or False. T memory cells are long-lived and functionally inactive
True
Name the 3 stimuli critical for full T cell activation
- Antigen recognition(initiates process)
- Costimulation(maximizes the response)
- Cytokines ( amplifies the response and directs it along various differentiation pathways
True or False TCR and the CD4 or CD8 coreceptor together recognize the complex of peptide antigens and MHC molecules on APC.s, and this recognition provides the initiating or first signal for T cell activation
True
What is the TCR that is expressed on all CD+4 and CD+8 cells consists of?
a and b chains both of which participate in antigen recognition
What are CD4 and CD8?
They are coreceptors and are expressed by mature MHC-restricted cell T cell. Both function with TCR to bid MHC molecules
True or False. When protein antigens are ingested by APCs from the extracellular milieu into vesicles, these antigens are processed into peptides displayed by class II MHC molecules
True
What type of ingested antigens do CD4+ and CD8+ cells recognize?
CD4+–antigens ingested from extracellular microbes
CD8+–antigens derived from cytosolic or nuclear antigens
What is the TCR complex made up of?
TCR, CD3, and teta chain
T/F The response of naïve T Lymphocytes to cell-associated microbial antigens consists of a series of sequential steps that result in an increase in the number of antigen specific T cells and the conversion of naïve T cells to effector and memory cells
True
Name the steps involved in the activation of naïve T lymphocytes
- Antigen Recognition
- Activation by production of cytokines
- Clonal Expansion
- Differentiation
- Effector T cells (CD4+ helper & CD8+ CTL and Memory T cells(CD4+ or CD+8)
What are the functions of each player in antigen recognition and costimulation by naïve T cells?
- The T cell receptor (TCR)- consists of an alpha and beta chain recognizes MHC associated peptide antigen
- CD4 and CD8 Coreceptors- Function with TCR to bind MHC molecule. Recognize Class I or Class II MHCs. CD4 recognizes Class II and CD8 recognizes Class I
CD4+ T cells recognize antigens ingested from extracellular microbes
CD8+ T cells recognize antigens derived from cytosolic or nuclear antigens - TCR complex - Made up of TCR, CD3 protein and teta protein chain
- Integrin Protein Leukocyte Function-Associated Antigen(LFA-1)- Binds to APC whose ligand on APCs is called intercellular adhesion molecule 1 (ICAM-1)- Ensures T cells binds tightly to APCs displaying microbial antigens
T/F The biochemical signals that lead to T cell activation are triggered by a set of proteins linked to the TCR that are part of the TCR complex and by the CD4 and CD8 Coreceptors
True
T/F Adhesion molecules on T cells recognize their ligands on APCs and stabilize the binding of the T cells to APCs
True
T/F The full activation of T cells depends on the recognition of co-stimulators on APC s in addition to antigen
True
What are the 2 signals in activation of naïve T cells?
- CD3 proteins and teta proteins
2. Co-stimulators proteins, CD-80 (B7-1) and CD-86 (B7-2) expressed by APCs
Name the receptor that recognizes the B7 proteins
CD28 which is expressed in virtually all T cells
T/F The activation of CD8+ T cells is stimulated by recognition of Class I MHC-associated peptide and requires co-stimulation and /or helper T cells
T
Which cells secrete cytokines in CMI?
CD4+ cells
Which cytokine is produced first
Interleukin-2 (IL-2)
. Fill in the blank:
1. T cells are activated typically in the _ zones of _____ and ______
- ______ attract naïve T cells and dendritic cells to the activation site.
- Dendritic cells display endocytosed protein antigens on _________ and peptides derived from cytosolic proteins by ___________.
- TCRs bind to and recognize ___peptide antigen or MHC molecule_________ and CD4/CD8 bind to and recognize ___ peptide antigen or MHC molecule____
- The ligand of the major T cell integrin LFA-1 is _______.
- The major co-stimulators present on macrophages to activate T cells are ______ and _____ their ligand on T cells is ______.
- T cell zone of lymph nodes and spleen
- Chemokines
- MHC II MHC I
- Peptide antigen or MHC molecule peptide antigen or MHC molecule
- ICAM-1
- CD80 (B7-1) and CD86 (B7-2)
CD-28
- The region of contact between the APC and the T cell, including redistributed membrane proteins, is called __________.
- Lck phosphorylates and activates _________.
- Some of the major transcription factors generated by the T cells in response to its activation are _____________.
- The mechanism of action of cyclosporine involves its blocking of the production of the transcription factor _____________
- Activated helper T cells express CD40L, which binds to _ on the APCs.
- When T cells combat intracellular antigens, they encounter ___, __ and ____ within the endosomes whereas some other antigens such as the ______ and _________ in the cytoplasm.
- Immunologic Synapse
- ITAMs
- NFAT, NF-kb and AP-1
- NFAT
- CD40L
CD40 on the APCs - Bacteria, Fungi, and protozoa
Viruses and rickettsiae
Activation site for T lymphocytes include _______ in the lymph node and ____________ in the spleen.
- If a naïve T cell recognizes the antigen presented by an MHC molecule but there is no co-stimulation, the T cell cannot be activated and is referred to as ___
- This cytokine is released by the APC during the activation of naïve T cell
_____ - Activated naïve helper T cell releases a cytokine called ___ which exerts an autocrine effect to help these cells differentiate into effector T cells.
- ____-antigens trigger the production of massive amounts of cytokines causing conditions such as hypovolemic shock.
1
13. Parafollicular cortex PALS 14. Anergy 15. IL-2 16. IL-2 17. Super
II. True/False? Correct the false statements.
1. _____ T cells can combat extracellular microbes.
- _____ Naïve T cells have the ability to perform effector functions.
- _____ Activation of T cells not only requires antigen recognition and costimulators, but also TCR complex aggregation (activation of many T cell receptors at once) and long-term or repeated stimulation with antigen.
- _____ CD4+ cells are required for CD8+ cell activation.
- _____ Each subset promotes its own development and may suppress the development of others.
- ____ Naïve CD8 cells contain granules of granzymes and perforins.
- _____ CTLA-4 and PD-1 function to enhance T cell activation.
- F
- F
- T
- F
- T
- F
- F
III. Rearrange the following:
1. Steps in the activation of naïve T cells in general:
a. Clonal expansion
b. Effector function
c. Activation (cytokine secretion)
d. Antigen recognition
e. Differentiation
__d___ __c___ __a___ __e___ __b___
2. Steps in the role of helper T cells in its own differentiation.
a. CD40-CD40L Engagement
b. T cell differentiation
c. Activation of helper T cells
d. Expression of CD40 L
e. Secretion of cytokines
__c___ ___d__ __a___ __e___ __b___
3. Steps in the role of helper T cells in the differentiation of CD8 T cells.
a. Effector CTLs
b. Activation of CD4 T cells
c. Secretion of cytokines by CD4 T cells
d. CD4 and CD8 cells recognize antigen on an APC
__d___ ___b__ __c___ ___a__
4. Steps in the differentiation of CD8 T cells with the help of APC (indirect role of CD4)
a. CD28-B7 Engagement
b. T cell differentiation
c. Expression of B7 by the APC due to cytokine released from the activated CD4
d. CD8 cells recognize antigen on an APC
__d___ __c___ __a___ __b___
- d c a e b
- c d a e b
- d b c a
- d c a b
IV. Matching:
1. Match the subset of TH cells formed from the effector TH cells in the presence of a specific type of cytokine and the type(s) of cytokines they in turn release:
Cytokine Subset of TH cells Cytokines they release a. IL-4 i. TH1 A. IL-17 b. IFN-γ ii. TH2 B. IL-22 c. IL-12 iii. TH17 C. IL-4 d. IL-5 D. IFN-γ E. IL-5 F. IL-13
\_\_a\_\_\_ \_\_ii\_\_\_ \_\_C, E, F\_\_\_ \_\_b\_\_\_ \_\_i\_\_\_ \_\_D\_\_\_ \_\_c\_\_\_ \_\_i\_\_\_ \_\_D\_\_\_ \_\_d\_\_\_ \_\_ii\_\_\_ \_\_C, E, F\_\_\_ d and TGF-β iii A, B
- Match the type of cytokine to their functions. Two or more cytokines may share the same functions.
Cytokine Function
a. IL-4 i. classical macrophage activation
b. IL-5 ii. IgG production
c. IL-13 iii. IgE production
d. IL-17 iv. inflammation
e. IL-22 v. alternative macrophage activation
f. IFN- γ
a. __iii__, b. __iii__, c. __iii___, d. __iv___, e. __iv___, f. __i, ii___