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41 Cards in this Set
- Front
- Back
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What is the type of host defense that is stimulated by microbes that invade tissues?
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Adaptive
It adapts to the presence of microbial invaders |
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What is the type of host defense that is always present in healthy individuals?
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Innate
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What is considered the first line of defense of innate immunity?
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Epithelial barriers and specialized cells and natural antibiotics present in epithelia
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What is the clonal selection hypothesis?
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It predicted that clones of lymphocytes specific for different antigens arise BEFORE encounter with these antigens and each antigen elicits an immune response by selecting and activating the lymphocytes of a specific clone.
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What allows for the specificity and diversity of the adaptive immune system?
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Lymphocytes can express clonally distributed receptors for antigens, meaning that the total population of lymphocytes consists of many clones and each clone expresses an antigen receptor that it is different from the receptors of all other clones
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Primary immune responses are activated by ______ lymphocytes by secondary immune responses are activated by _____ lymphocytes
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naive
memory |
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What cells are the key mediators for adaptive immunity?
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Lymphocytes
They are the ONLY cells that produce specific receptors for antigens |
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What are the ONLY cells capable of producing antibodies?
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B lymphocytes
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Which cells mediate humoral immunity?
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B lymphocytes
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How are humoral immune responses elicted?
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Soluble antigens and antigens on the surface of microbes and other cells that bind to the B lymphocyte antigen receptors
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What are the cells of cell-mediated immunity?
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T lymphocytes
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What triggers recognition of the T lymphocyte antigen receptors?
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Peptide fragments of protein antigens that are bound to specialized peptide display molecules called MHC molecules on the surface of specialized cells called antigen-presenting cell (APCs)
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What is the role of helper T cells?
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CD+4 cells help B lymphocytes to make antibodies and help phagocytes to destroy ingested microbes
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What is the role of regulatory T lymphoccytes?
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This is a special subset of CD+4 cells that functions to prevent ot limit immune respsones.
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How are cells killed that harbor intracellular microbes?
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By CD+8 lymphocytes (cytotoxic T lymphocytes)
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Which class of lymphocytes are considered part of the innate immunity?
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Natural killer cells
they kill infect host cells, but they do not express the kinds of clonally distributed antigen receptors that T cells and B cells do |
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What is the maturation site for B cells?
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Bone marrow
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What is the maturation site for T cells?
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Thymus
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What is the trigger for the antigen-specific lymphocytes proliferate and differentiate into effector and memory cells?
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When naive lymphocytes recognize microbial antigens and also receive additional signals induced by microbes.
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What is the role of effector B lymphocytes?
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they are called plasma cells and they produce antibodies
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What is the role of effector CD+8 T cells?
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They have the machinery to kill infected host cells
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What determines the life-span of most effector cells?
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Most effect lymphocytes are short-lived and die as the antigen is eliminated
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The frequency of memory cells _____ with age.
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increase
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What is the fate of antibody plasma cells after the infection is resolved?
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They may migrate to the bone marrow and continue to make small amounts of antibody after the infection is eradicated
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The lifespan of Naive cells lasts _____ vs the effector cells that last _____.
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weeks to months
days |
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What cells do the follicular dendritic cells work to differentiate?
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B cell in the follicles
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Where are dendritic cells commonly found?
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In the epithelia; they capture protein antigens of microbes and transport the antigens to the regional lymph nodes
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What distinguishes primary from secondary lymphoid organs?
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Primary lymphoid organs are generative where T and B lymphocytes mature
Secondary lymphoid organs are where adaptive immune responses are initiated. |
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What are the peripheral lymphoid organs?
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The lymph nodes
spleen the mucosal and cutaneous immune systems |
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Where are T cells located within the Lymph node?
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In the paracortex
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Where are B cells located within the lymph nodes?
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In the follicles which are located in the cortex
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The _____ serves in immune responses to blood-borne antigens and the ______ serve in immune responses to lymph-borne antigens.
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Spleen
Lymph nodes |
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What are the two anatomically defined mucosal lymphoid tissues in the body?
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Peyer's patches
Pharyngeal tonsils |
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Where is the germinal center located?
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In the center of the follicle
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In the spleen, T lymphocytes are concentrated in ________ and B cells are found in ________
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periarteriolar lymphoid sheaths surrounding small arterioles
in the follicles |
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How are B lymphocytes recruited into the follicles of lymphoid organs?
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FDCs secrete chemokines for naive B lymphocytes
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How are T lymphocytes recruited to the spleen and lymph nodes?
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By stimulation of the naive T lymphocyte receptor CCR7
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What trigger the migration of B cells and T cells toward each other within the follicle?
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After activation of the lymphocytes by microbial antigens , they alter their expression of the chemokines causing the migration toward each other?
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Why do the B cells and T cells migrate toward each other within the follicle after antigen activation?
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The helper T cells interact with and help B cell to differentiate into APCs
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Where would we expect effector B lymphocytes to migrate to after activation?
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They do not need to migrate to sites of infection - they stay in the lymphoid organs and secrete antibodies into the blood stream
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How do naive T cells enter into lymph nodes?
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the naive T cells enter via high endothelial venules ( specialized postcapillary venules)
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