Immunology Flashcards
what is immunity?
protection against foreign pathogens or substances
who is the father of immunology?
Edward Jenner
what are commensal organisms?
organisms that cause no harm
explain what normal flora is?
when microorganisms function in a metabolic and immune balance called homeostasis
when are microbes considered pathogenic?
when they manage to penetrate the immune defense
what does dysbiosis lead too?
immune overstimulation leading to inflammation
how does our immune system distinguish between self and non-self?
when a pathogen invades as an intact organism, the cells of the immune system recognize its molecules, NOT the whole pathogen
what are the strategies of pathogens?
- inactivate immune proteins
- resist immunological weaponry
- deception
- hide
- intracellular parasitism
- distractionns/decoys
- mimicry
the adaptive immunity results from what?
the acquisition of recombination activating gene (RAG) Genes for somatic recombination of gene segments to code for B/T cell receptors
what are the characteristics of adaptive (aquired) immunity?
- protection develops after infection
- learned through experience of lymphocytes
- antigen specific
- memory
what is humoral immunity?
combating pathogens via antibodies
what are antibodies also called?
gamma globulins or immunoglobulins
what is passive immunity?
antibodies being transferred between individuals
what is active immunity?
natural infection or vaccination engage the immune defense of a person to make its own antibodies
which type of immunity is long lived because the immune system develops memories?
active
what is cell-mediated immunity?
the work of pathogen-specific T cells, which can act directly to eradicate the infectious agent as well as aid other cells in their work
how is the immune defense system populated aka hematopoiesis?
hematopoietic stem cells (HSCs) differentiate into many different blood cells through two major types of progenitor cells
where does hematopoiesis occur?
bone marrow
what are the two progenitor cells that the hematopoietic stem cells differentiate into?
common myeloid and common lymphoid
what are the four main types of cells derived from the common myeloid progenitors?
- red blood cells
- megakaryocytes
- monocytes/macrophages/dendritic cells
- granulocytes
what cells can differentiate into dendritic cells?
monocytes/macrophages
what are the functions of monocytes/macrophages?
- repair/remodel by producing anti-inflammatory signals and signalling tissue healing
- engulf pathogens
- present antigens to T lymphocytes
- release vessel dilating substances
- produce antimicrobials, digestive enzymes and free radicals
- contain Fc receptors
what is the main function of dendritic cells?
- capture microbial and other antigens and display them to naive T lymphocytes that causes the proliferation and differentiation of the lymphocytes (initial activation)
what are the 4 granulocytes?
- neutrophil
- eosinophil
- basophil
- mast cell
what are some characteristics of neutrophils?
- prodominent cell at wound site
- highest % of WBC
- direct harm to pathogens
- phagocytic
- produce digestive enzymes and free radicals
- secrete mediators during inflammation involved in vasodilation
what are some characteristics of eosinophils?
- induces ROS formation
- low % of WBC
- indirectly causes vasodilation by degranulation
- produce cytokines that modulate adaptive responses and chemokines
- anti-viral
- predominant for fighting parasitic infections
what are some characteristics of basophils/mast cells?
- release histamine for vasodilation
- release heparin for increase in blood flow
- release leukotrienes to regulate inflammation
- allergies
- contain Fc receptors
what are the two cells from the lymphoid lineage and what are they used for?
- B lymphocytes for the humoral response
- T lymphocytes for the cell-mediated response
what are some characteristics of B lymphocytes?
- develops in bone marrow
- express B cell receptors that bind antigens
- present antigens in a secondary response
- produce antibodies
- differentiate into plasma cells
what are the five types of T lymphocytes and their function?
- cytotoxic T lymphocytes: extracellular killing (lyse)
- T helper cells: up regulation of immune response
- T regulatory cells: down regulation of immune response
- NKT cells: shares both natural killer cell property and T cell properties
- Memory T cells
what is the function of the NKT cells?
- bind foreign as well as self lipids and glycolipids
- produce large quantities of cytokines
- activate natural killer cells
explain what clusters of differentiation means?
B, T and NK cells appear similar but different sets carry different surface molecules
what CD proteins do T helper cells and T cytotoxic cells express?
TH cells: usually CD2, CD3, CD4 and CD 5
* sometimes CD8
TC cells: usually CD2, CD3, CD5 and CD 8
* sometimes CD4
what CD proteins do NK cells express that the others do not?
CD16
what does primary and secondary lymphoid organs mean?
- primary means they develop immune cells
- secondary means the immune response is initiated here
where does hematopoiesis begin?
yolk sac
B lymphocytes develop in contact with what?
stromal cells of the bone marrow
T lymphocytes develop in contact with what?
stromal cells of the thymus
secondary lymphoid organs include?
- lymph nodes
- spleen
- mucosa-associated lymphoid tissues (MALT)
what occurs in lymphoid nodes?
- antigen-specific lymphocytes come in and scan for foreign molecules funneled there
how do cells send signals in both the innate and adaptive branches?
through mediators known as cytokines and a subset called chemokines that recruits specific cells
what are the steps of an infection?
- endothelium expresses intracellular adhesion molecules (ICAM) and produces chemokines
- immune cells are activated
- immune cells bind to the ICAM using their adhesion molecules
- leukocyte enters surrounding tissue by pushing between endothelial cells
- inflammation develops
what are three dysfunctions of the immune system?
- hypersensitivities aka allergies / asthma
- autoimmune disease which are misdirected immune responses
- immunodeficiency which is an acquired or genetic loss of immune function
