L2: Cells and Tissues Flashcards
What are non-self entities?
Things that express molecules (antigens) that can be recognized by cells of the immune system
What are the major groups of human pathogens?
Viruses, bacteria, fungi, parasites
How was smallpox vaccine discovered?
Smallpox is caused by the variola virus. Discovered that milkmaids, who were exposed to cow pox (variolae vaccinae) did not get smallpox. Then took scrapings from pustules of milkmaid and inoculated someone, then did the same w/ small pox and pt did not get smallpox. Smallpox was officially eradicated in 1979
What is the most primitive form of the immune system?
Innate immunity
How long after infection does innate immunity kick in?
Minutes to hours
What does the innate immune system consist of? What does the adaptive immune system consist of?
Innate: epithelial barriers, complement, phagocytes, NK cells
Adaptive: B lymphocytes, T lymphocytes
What microbe does humoral immunity respond to? What are the responding lymphocytes? What is the effector mechanism?
Microbe: extracellular bacteria
Responding lymphocytes: B lymphocyte
Effector mechanism: secreted antibody, causing elimination of bacteria
What microbe does cell-mediated immunity respond to? What are the responding lymphocytes? What is the effector mechanism?
Microbe: phagocytosed microbes in macrophage and virus-infected cell
Responding lymphocytes: T lymphocytes
Effector mechanism: For phagocytosed microbes in macrophage, causes activation of macrophage leading to microbial killing
For virus-infected cell, causes lysis of infected cell
How are humoral and cell-mediated immunity transferred?
Humoral immunity is passively transferred by serum (antibodies)
Cell-mediated immunity transfer requires transfer of cells
What is the effector function of B lymphocytes?
Produces antibodies
Causes neutralization of microbe, phagocytosis, complement activation
What is the effector function of helper T lymphocytes?
Produces cytokines
Causes activation of macrophages, inflammation, and activation (proliferation and differentiation) of T and B lymphocytes
What is the effector function of cytolytic T lymphocytes?
Killing of infected cell
What is the effector function of natural killer (NK) cells?
Killing of infected cell
What are the phases of the adaptive immune response?
Recognition phase Activation phase Effector phase: elimination of antigens Decline (homeostasis): apoptosis Memory: surviving memory cells
When antigen comes in, why is there a lag time before immune response occurs?
There is activation, clonal expansion, and differentiation of B cells to produce antibody
How is secondary immune response different from primary immune response?
Lag time is shorter
Level of antibody produced is higher
Quality of antibody is more specific
Lasts longer in circulation
In hematopoiesis, what determines what the stem cell becomes?
Microenvironment of bone marrow and also cytokines that are present
Where does B lymphocyte and T lymphocytes maturation occur?
B lymphocytes in bone marrow
T lymphocytes in thymus
Once they are released to the blood, where do B and T lymphocytes take up residence?
In the peripheral lymphoid organs
Lymph nodes
Spleen
Mucosal and cutaneous lymphoid tissues
What criteria are used to distinguish various lymphocyte subsets?
Cell surface markers
Patterns of cytokine production
Functional characteristics
What are significant surface markers of human B cells?
Antibody molecule that is stuck in the membrane w/ the 2 antigen combining sites exposed
MHC I
MHCII
What are the significant surface markers of human T cells?
MHC I
T helper cell: CD4
T cytotoxic cell: CD8
What are the T cell subsets? What do they do?
Helper T lymphocytes: make cytokines that amplify the immune response; cause activation of macrophages, inflammation, activation (proliferation and differentiation) of T and B lymphocytes
Cytolytic T lymphocytes (CTLs): killing of infected cell
How are natural killer cells different from cytotoxic T cells?
They are part of innate immune response that don’t require antigen recognition to kill infected cell
What is an alternate name for NK cells?
Large granular lymphocytes bc of the unique granules in their cytoplasm
What are the significant cell surface markers of human monocytes/macrophages?
MHC II
What are the antigen presenting cells?
Dendritic cells and macrophages
Describe how antigen presenting cells present antigen peptides
- Bacterium infects macrophage and enters vesicle, producing peptide fragments
- Bacterial fragments are bound by MHC class II in vesicles
- Bound peptides transported by MHC class II to the cell surface
What does T helper cell recognize?
Recognizes complex of bacterial peptide w/ MHC class II and activates macrophage
What lymph vessels go into and out of lymphoid tissues?
Afferent vessels coming in and efferent going out
Where do all lymphatic vessels coalesce?
In the major lymphatic vessel of the body, the thoracic duct, which empties into the peripheral circulation around the great vessels near the heart
Where do B cells reside in lymph nodes?
In germinal centers (follicles) which are in the periphery of the lymph node
Where do T cells reside in the lymph node?
In the T cell zone, which is just beneath the B cell zone
