Intro lecture Flashcards
Organs of the immune system
Bone marrow, thymus, spleen, lymph nodes, adenoids, tonsils, and appendix
Method of transfer for immune system cells
Through lymph or through blood
Location of lymph node clusters
Axilla, neck, abdomen, and groin
Germinal center
Where antibody is produced by B cells after antigen stimulation
Paracortex
Mostly T lymphocytes
Medulla
Mostly macrophages
Main cells involved in the first line of defense
Macrophages and neutrophils
Monocytes
Mature into specialized macrophages that migrate to the peripheral tissues of the body and prepare for microbial invasion
Where do large numbers of mature macrophages reside?
In connective tissue, the digestive tract, the respiratory tract, spleen, and in the liver (Kupffer cells)
Neutrophils
Short-lived cells that circulate in the blood. Migrate to place of infection when they occur to assist macrophages
Dendritic cells
Macrophage-like and are highly specialized for phagocytosis and presentation of antigens
Eosinophils are the principal defender against what kind of pathogen?
Parasites
Cluster of differentiation antigens
(CD’s). Different ones are expressed on the cell surface of different types of cells to differentiate them from each other
CD marker on granulocytes
CD15
CD marker on monocytes
CD14
CD marker on dendritic cells
CD11c
CD marker on T cells
CD3
CD marker on cytotoxic T cells
CD8
CD marker on helper T cells
CD4
CD marker on B cells
CD19
CD marker on natural killer cells
CD56
What happens when a foreign microbe enters the human body?
Phagocytosed by dendritic cells, which then make antigens and present them to T cells after traveling to peripheral lymph organs
What happens if the foreign antigen is in the blood stream?
It is captured by the spleen and dealt with there
Where are class I MHC molecules expressed?
In virtually all nucleated cells
Where are class II MHC molecues expressed?
In B cells, macrophages, monocytes, and dendritic cells
What do MHC molecules do?
Present foreign antigens as antigenic peptides
Antigen
Molecules that stimulate the production of/ bind to antibodies
Epitopes
Multiple antigenic components on a pathogen
Definition of antigen
Any non-self molecule that is capable of eliciting the production of antibodies
Innate immunity
Provides initial defense against microbes and is not antigen specific
What happens if innate immunity fails to eliminate the pathogen?
The adaptive immune system responds in a specific manner to eliminate the invading microorganism
Adaptive immunity
Mediated by B cells and T cells; antigen-specific. Takes time to elicit effects.
What portion of adaptive immunity do B cells control?
Humoral response
What portion of adaptive immunity do T cells control?
Cell-mediated response
Compare humoral immunity to cell-mediated immunity.
Humoral immunity is the release of antibodies to impair the pathogen. Cell-mediated either phagocytoses the pathogen directly or releases cytokines that kill the foreign antigen
Stages of the adaptive response
- Recognition of the antigen
- Phagocytosis of the antigen by an APC
- Presentation of the antigen
- Activation of T/B lymphocytes
- Clonal expansion and differentiation
What happens as antigen is eliminated?
The immune response slows, and effector lymphocytes undergo apoptosis except for ones that are kept as memory cells
What happens to the B cell when it encounters its match?
Antigen attaches to the receptor, the B cell clonally expands, differentiates, and some become plasma cells that produce the antibodies at rates up to 10,000,000/hour
Two major ways T cells are immunogenic
Kill things directly or release cytokines that help other cells
Which cells make cytokines?
T helper cells
What do cytokines do?
They are factors for growth, differentiation, and activation of B and T cells
What chemicals do cytotoxic T cells and natural killer cells release?
Perforin and granzymes
Cytotoxic T cells react to what kind of MHC?
Class one
Against what does cell-mediated immunity protect?
Bacteria, fungus, and viruses that are inside a host cell and therefore inaccessible to antibodies, as well as cancer cells.
B cell clonal expansion requires what?
Cytokines produced by T helper cells
Helper T cells respond to MHC class __ molecules.
II
What do antibodies do?
They can activate them; they also mark them for destruction by other cells and the complement system
What is the complement system?
A series of 30 proteins found in plasma that will kill an invader
Secondary response
When the same antigen is encountered twice, the response the second time will be much greater and faster; serves as a protective response.
Active immunity
The body builds up its own stores of immune cells and mounts and immune response on its own (can be from general infection or artificially by vaccination)
Passive immunity
Passed from one person to the other; e.g., breastfeeding or antibody transfusion
