introduction to immunology Flashcards
how do we know that we have an immune system?
body reacts to foreign substances
- cuts/scrapes, redness, swelling, secretions, etc.
infection protects us from repeated infections
vaccines work
our body can immunologically reject organ transplants and blood transfusions
what’s a hypersensitivity reaction?
extreme or unnecessary immune response that the body has to an antigen
how does inflammation appear on the skin/externally?
redness and swelling
what is meant by “infection protects us from repeated infection”?
in subsequence infection (or exposure event to the same antigen), we get a faster and larger immune response due to immunological memory, a part of the adaptive immune response
note: there’s no improvement in the innate response
describe the relationship between antigens and antibodies
ANTIbody GENerator
antibodies are produced by B cells in response to antigens and used to mark antigens for destruction
antigens are foreign substances
why do vaccines work?
due to the adaptive immune response and immunological memory
what did E. Donnall Thomas win the nobel prize for in regards to immunology? describe his findings
for his study on bone marrow transplants and immunological rejections – he conducted the first match bone marrow transplant in humans
FINDINGS: if subjects were…
immunologically mismatched, transplants were immunologically rejected = death
immunologically matched = transplants were tolerated for a few days before patient’s health declines
immunologically matched and treated with methotrexate (which wipes out recipient’s immune system) patient experienced better results and was unable to immunologically reject the transplant
how do we know that we need an immune response?
severe combined immune deficiency in children is lethal without treatment
immune deficient model organisms are unable to prevent infection
- experiment with a fly where they had their toll-like receptors removed (TLRs), an essential part to the immune system -> they developed a fungal infection
what’s it called when one is born with no functional immune system? and what treatment do they require?
primary immune deficiency
requires bone marrow transplant to be treated or the child will die before their 1st birthday
how was a child able to extend their life over a year even though children with primary immune deficiency are expected to die before their first birthday
a patient was put into a sterile plastic bubble, extending his life - he lived for 8 years!
he died after side effects of a bone marrow transplant that wasn’t done well
what is the purpose of the immune system?
defence against invaders
self nonself discrimination
- to discriminate against nonself
- exception: fetus
detection of danger/damage
- bacteria/microorganism is not a problem till it harms us and takes away from our resources
to achieve peace and harmony with our enemies
what are the components of the immune system? (3)
barriers
cells
soluble molecules (humoral)
—– anything in the blood or in liquid form (outside the cell)
what are the barriers of the immune system? (4)
mechanical
chemical
microbiological
nutritional
describe mechanical barriers in the immune system (epithelial cells)
epithelial cells are joined by tight junctions that prevent things from going in between the cells
the epithelial cells make up the skin and our inner linings
epithelial cells are also capable of secretions like mucins/mucus and other chemical defences (saliva, tears, etc.)
epithelial cells, especially those of the skin, regenerate and are constantly dividing and replacing dying cells — this is desquamation, shedding that removes anything that may attach to it!
what are langerhans
a specialized macrophage that can travel thru the epidermis
describe skin as an a example of a mechanical barrier
keratinocytes produced from progenitor cells will produce keratin that hardens forming a keratin shield called the corneal layer
langerhans cell, a specialized macrophage that can travel thru the epidermis
other immune cells are present in the dermis of the skin: mast cells, dermal DC, macrophages…
describe the linings of the lungs as an example of a mechanical barrier
goblet cells, a specific type of epithelial cell secretes mucus which lines the lungs and protects us from invaders
cilia is constantly moving material thru lungs — this is why we have the urge to cough and expel materials
what are examples of chemical barriers in the immune system?
lysozymes
antimicrobial peptides
fatty acids
what are lysozymes?
secreted by epithelial cells
enzymes that digests bacteria and its cell wall – specifically the peptidoglycan component of bacterial cell walls
what are antimicrobial peptides?
short positively charged peptides – has antimicrobial properties
there are 21 different antimicrobial peptides in humans
how are fatty acids part of the immune’s system chemical barrier?
both saturated and unsaturated fatty acids have antimicrobial properties, inhibiting the growth of bacteria
what are defensins?
small molecules used in immunological defense – a chemical barrier
includes:
antimicrobial peptides
fatty acids
describe the microbiological barriers in the immune system
most bacteria are not pathogenic do not cause harm - can have positive impacts too!
—- in this case, there’s no DEFENSIVE immune response; immune response is present
environment factors (e.g. diet, maternal) and genetics help shape the microbiome
invaders must compete for resources with bacteria already present in the body
describe nutritional barriers in the immune system
microbes need metals, such as iron to function and replicate – needed by their enzymes
to inhibit microbial growth, metals are hidden from microorganisms
how is iron a nutritional barrier in the immune system? how do pathogens try to combat this?
in our body, iron is not present in the free state
—— in the cell, iron is complexed with heme, which is bound by hemoglobin
—— iron is actively pimped out of intracellular compartments by NRAMP1 - this removes iron from inside the cell
—— outside the cell, heme is bound haemopexin (HPX)
—— free hemoglobin is bound by haptoglobin (HP) – removes hemoglobin in the blood
to combat this:
bacteria will try to collect the iron by secreting siderophore molecules that bind to the iron to import it back into the bacteria
