Immunity-Chapter 5 Flashcards
(32 cards)
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