Intro to immunology Flashcards
What is immunology from a historical perspective?
Immunology got its name from the latin word “immunis”, that means “exempt” which came out of the observation that people that had recovered from sickness were exempt from being infected again, indicating that the body could somehoow remember and had protection to the sickness. The first accounts of this are from 430 BC! The idea that unseen invaders was the cause came about muuuuch later, germ theory, but the observed phenomena led to todays vaccines!
What are some classic examples of of vaccinations?
Smallpox and Rabies where among the first and most successful early vaccinations. Smallpox was eradicated in 1977, the first one! This led to universal vaccination no longer being necessary which is good as vaccination can carry a risk in some cases.
Explain the principle of vaccines in short.
The principle behind vaccination is that exposure to safe forms of an infectious agent can result in future acquired protection, or immunity, to the real and more dangerous infectious agent.
Explain the term “herd immunity” in short.
Herd immunity means that a large fraction of a community is immune, which decreases the amount of people that can harbour and spread the disease further, which protects the unimmune fraction.
Immunity involves both humoral and cellular components, what do these refer to?
Humoral (bodily fluids) immunity mainly refers to antibodies produced by B-cells while cell-mediated immunity refers to T-cells that can eradicate pathogens, clear infected self-cells, or aid other cells in inducing immunity.
What is “passive immunity”? Give one example of how it’s done.
Passive immunity is acquired through getting antibodies administered from another source, thus not producing it yourself. That is why it’s referred to as “passive”. An example of passive immunity is babies getting antibodies from their mothers milk which protects them or immunocompromised individuals getting antibodies as protection against disease.
Note: Passive immunity is relatively short lived as the cells producing the antibodies are not transferred, only the antibodies. Active immunity (aquired upon encounter with the pathogen is much more long lived, some even for life)
The humoral and cellular immune response uses the same mechanism for recognition of pathogens, explain this mechanism in short.
Both antibodies and T-cells recognise antigens by surface receptor binding. This binding is highly specific, down to the difference of one amino acid. Each cell have many copies of the same receptor, so each cell is able to recognise a specific antigen. This specificity is generated by random gene segment rearrangements during development, a highly regulated process.
Describe the terms “pathogen” and “pathogenesis”.
Organisms causing disease are termed pathogens, and the process by which they induce illness in the host is called pathogenesis.
Which are the four types of human pathogens?
Viruses, fungi, parasites, and bacteria. Grouped based on shared characteristics.
The immune response to these differ not only by the type of pathogen, but also depending on route of infection and location/microenvironment of the infection. For example, some bacteria are tolerated in our GI-tract and is incorporated in our gut-biome, while the same bacteria would be aggressively attacked if it resided elsewhere/was introduced into blood.
Is the immune response always the same?
No! The Immune response quickly becomes tailored to suit the assault - key to an effective response towards a wide variety of pathogens, infection routes and intra- or extracellular location.
During the initial stages of infection, the receptors that first recognize the foreign agent help the immune response categorize the offender and tailor the subsequent immune response.
Unique pathways begin to emerge that are specific for different types of pathogens, such as cytotoxic T cells that kill virally infected host cells, T helper cells that assist other immune cells, and antibodies secreted by B cells to fight extracellular infection.
What is meant by “tolerance” in immunology?
Tolerance is an important concept referring to the immune systems ability to discriminate between self and non-self. As the recognition molecules for the adaptive immune system is randomly generated, there is a need to make sure that they don’t bind and attack self-antigens as that would be detrimental to the host. A functional adaptive immune system is said to have “tolerance” to self-antigens - it doesn’t attack them.
Autoimmune diseases are caused by defective self tolerance.
There are two main parts of immunity in vertebrates, which and what characterize them?
- Innate immunity: first line of response - fast acting but less specific, inherited and consists or physiological barriers, phagocytic cells, PRR (pattern recognition receptors) that recognizes PAMPs (pathogen associated molecular patterns) and the complement system. The responses of the innate system is kind of “fixed” and also activates the second line of defence.
- Adaptive immunity: the second line of defence - slower but extremely specific and effective, huge variation that is not inherited but generated randomly, consistes of B and T cells (lymphocytes). This system “evolves” during infection to be the perfect counterattack to the pathogen.
Remember, both of these are equally important and communicates. One can not exist without the other. Although some not so severe infectioons can be handled by the innate immunity alone.
Where are immune cells found? is any organ central?
Everywhere! Immune cells need to be everywhere to patrol for pathogens, but the most central organ in the immune systetm is the lymph nodes, where innate and adaptive immunity meet.
How does immune cells communicate?
The immune cells communicate via cell-cell interactions and via messenger proteins called cytokines (the hormones of the immune system). Chemokines are a subset of cytokines that act as chemoattractants that can recruit immune cells to where they’re needed, also inducers of the imflammarory response (swelling, heat, redness, pain/tenderness).
The adaptive immunity have a feature that is very unique; memory, explain it in brief.
The immunologic memory have the ability to respond much more swiftly and with greater efficiency during a second exposure to the same pathogen. Unlike almost any other biological system, the vertebrate immune response has evolved not only the ability to learn from (adapt to) its encounters with foreign antigen in real time but also the ability to store this information for future use.
So, during the primary response (first exposure) the lymphocytes are produced, honed and stored, and during the secondary response (repeated exposure), kin to the stored lymphocytes, aka memory lymphocytes, are re-enlisted to fight again, a much swifter and more efficient response. So the strategy is saved, not the pathogen.
Note, for some infections, there is need for several exposures to provide a good enough protection, this is the basis for booster shots of vaccines.
