W1L1/2 - Foundations of Immunobiology Flashcards
Self Discrimination
Ability to recognise and respond to molecules that are foreign, yet not respond to molecules that are part of self
Innate Immunity
Natural Immunity
Cells, tissues and molecules that are already present in a healthy body at the time of exposure to either a foreign microbe or agent/molecule
Provides a rapid, generalised, non-specific response
- minutes, hours to days
Doesn’t involve antibodies
Acquired Immunity
Adaptive Immunity
The specialised induced/adaptive response to a particular foreign microbe or agent that develops slowly (days to weeks)
Two types:
1. Humoral - the production of antibodies (B cells)
2. Cell mediated - killing of infected or damaged host cells (T cells)
Examples of Innate Defences
Surface barriers: Skin Mucous membrane Internal defences: Phagocytes Fever Inflammation NK cells
Antibody
Large Y-shaped protein used by immune system to identify and neutralise foreign material
Only one part of the foreign material is recognised by one antibody molecule
- this part is the antigenic determinant or epitope
Haematopoiesis
The process by which all of the specialised cell types develop from a common pluripotent bone marrow stem cell
Some cell types differentiate in the bone marrow and others in the periphery:
Blood
- all cells transit through the blood
The tissues:
- T cells mature in the thymus
- B cells mature in the bone
- Both move into various lymphoid tissues after maturation
What are the Granulocytes and Agranulocytes
Granulocytes - neutrophil - eosinophil - basophil Agranulocytes - lymphocyte - monocyte These are all examples of Leucocytes
Leucocytes
WBC
Defend against disease
Can leave capillaries via process called diapedesis
They can move through tissue spaces by ameboid motion and chemotaxis
Neutrophils
Also called polymorphonuclear (PMN) leucocytes
Short lived (12 hrs)
Exit blood to engage foreign molecules
Very phagocytic
Produce peroxide and superoxide radicals which are toxic to microorganisms
First cells on the scene during inflammatory response
Eosinophils
Red staining cytoplasmic granules
Bi-lobed nucleus
Release enzymes to digest parasitic worms
Role in allergies, asthma and in modulating immune response
Basophils
Rarest WBC
Large purple-black granules containing histamine
- histamine acts as a vasodilator to attract WBC to inflamed sites
Similar to mast cells except mast cells found in tissue and not blood
Lymphocytes
Second most numerous WBC Quite small Large dark-purple circular nuclei Mostly found in lymphoid tissue 3 types: - T lymphocytes - B lymphocytes - Natural killer cells (NK cells)
T Lymphocytes
Activate macrophages and act against virally infected cells as well as tumor cells
B Lymphocytes
Give rise to plasma cells, which produce antibodies
NK Cells
Derived from same precursor as T lymphocytes
Attack cells that lack self cell-surface receptors
- induce apoptosis
When NK cells make contact with target cells they secrete chemicals that enhance inflammatory response
Monocytes
Largest leukocytes
Pale-blue cytoplasm and many granules
Kidney shaped nuclei
Leave circulation, enter tissues, and differentiate into macrophages
Macrophages
Activate phagocytic cells
Activate lymphocytes to mount an immune response
Widespread in lymphoid organs and connective tissue in different forms:
- Osteoclasts in bone
- Kupffer cells in the liver
- Alveolar macrophages in lung
- Microglial cells in CNS
All are cell components of the reticuloendothelial system (RES)
Dendritic Cells
Specialised antigen presenting cells (APC)
- most effective antigen presenter
- key link between innate and adaptive immunity
Found as:
- interdigitating cells of the thymus
- in the skin, called langerhans cells
Function:
- phagocytise pathogens
- enter the lymphatics to present antigens to T cells inside lymph nodes
Main Functions of the RES
Phagocytose microbes/foreign material in the blood
Destruction of aged or imperfect cells
Ubiquitous Microbes
Generally don’t cause infection
With immune deficiency in host may result in infection
