Lecture 1 Flashcards
Define immunology
study of host defense against ; infectious agents, neoplasia, injury
name some infectious agents
viruses, bacteria, fungi, parasites
what is the key distinction of infectious agents?
self from non-self
key distinction of neoplasia?
self from altered self
key distinction of injury?
damaged self
what 2 things greatly advanced our understanding of immune system and its fn?
molecular biology and genomics
True or False: Immunology is static
False; non-static, always there, responds immediately
What factors affect the immune system?
age, nutritional status, host genetics, drugs, confounders/co-infectors, smoking, stress
What are the 2 divisions of IS?
innate and adaptive
What are the 2 components that make up each division?
humoral (cell-free) and cellular
Describe components of innate immunity
always there, identifies with non-self
humoral: complement, cytokines/chemokines, antimicrobial peptides
Cellular: monocytes (macrophages and dendritic cells), NK cells, granulocytes (mast cells, eosinophils, basophils, neutrophils)
Describe components of adaptive immunity
slower response, identifies with specific antigens
Humoral: antibodies
Cellular: B cells, T cells (helper T cells, cytotoxic T cells, regulatory T cells)
Milestones
What is immunity mediated by?
organs, cells and molecules
Where are immunocytes derived from?
bone marrow during hematopoiesis
What are the two types of responses?
natural or acquired; innate/existing/non-clonal vs adaptive/induced/clonal
Name the components of the immune system?
soluble, cellular and tissues
What produces soluble components?
immune cells, fibroblasts, epithelial cells, hepatocytes
What do soluble comp affect?
differentiation and activities of immune cells; can have direct action on invading pathogen or tumors
What do cellular comp involve?
innate and adaptive responses
What do tissues involve?
primary and secondary organs
Where do cells of immune system originate?
in the bone marrow (from hematopoietic stem cells), migrate through the blood and lymphatic systems, then function in peripheral tissues
Simply describe differentiation pathway
hematopoietic stem cell –> common lymphoid progenitor (B/T cell, NK cell) OR common myeloid progenitor (granulocyte macrophage progenitor -> neutrophil, eosinophil, basophil, monocyte; megakaryocyte erythrocyte progenitor -> megakaryocyte (platelets), erythroblast (erythrocyte))
What drives differentiation of immune cells down each pathway?
cytokines
What do innate and adaptive immunity rely on?
WBC called leukocytes
In the fetus, where are stem cells first produced?
liver and yolk sac
What are the two pathways stem cells can differentiate into?
myeloid or lymphoid
Describe features of neutrophils
- also called PMNs - polymorphonuclear neutrophil granulocyte
- most numerous cell of innate immunity
- responsible for phagocytosis and digestion of bacteria and particles
- contain multi-lobed nuclei and cytoplasmic granules
- short life spans - 2 days
- species differentiation in % of blood leukocytes (low in rum, high in carnivores)
Describe features of granulocytes (esoinophil, basophil, mast cell)
- kills antibody-coated parasites
- release of granules containing histamine - agents
Describe features of macrophages
- most important phagocytic cell (regulating homeostatic processes and wound healing)
- mononuclear cells found in blood and all tissues
- rel long-lived (months) in certain tissues
- secrete pro-inflammatory cytokines
- present processed antigen to T cells
- phagocytosis
- help initiate adaptive immunity
- antigen presentation
Describe dendritic cells
- NOT dendrites
- found in low numbers in tissues (skin epithelia, intestinal, respiratory, repro mucosae)
- migrate to draining lymph node after pathogen uptake
- most important APC
- provides link btw innate and adaptive
- most either lymphocytic or myeloid origin
Describe lymphocytes
- lymphoid progenitor from bone marrow or bursa
- leave bone marrow only partially mature
- B cells mature in lymph nodes, T cells differentiate in thymus
- small, round cells -> surface markers distinguish classes
- mediate adaptive immunity (receptors specific for epitopes)
- found in blood and lymphoid organs
- once “selected’ –> clonal replication
- get rid of ones that respond to “self”
Describe features of NK cells
- lymphocyte lineage but NOT really lymphocyte
- possess different antigen receptors than B/T cell
- doesn’t require thymus for maturation
- 15% of blood lymphocytes
- most in secondary lymphoid organs
- kill tumor cells and virally-infected cells
- possess an Fc receptor -> bind many types of antibodies
- secrete interferons, IFN
Describe the innate immune response
immediate, pre-formed molecules, specificity inherited in genome, response identical each exposure, mediated by monocyte, neutrophil and NK cells, no antigenic memory
Describe adaptive immune response
delayed response, receptors rearrange, clonal expansion of cell subsets, response improves over time, mediated by T and B cells, antigenic memory
