lymphocytes Flashcards
what is the size of lymphocytes?
7-14 µm
what are some features of lymphocytes?
- are non-granular
- have a large nucleus
- only a small amount of the cytoplasm is visible due to the size and shape of the nucleus
what are the three different cells that a lymphoid progenitor can form:
- B-lymphocyte
- T-lymphocyte
- Natural Killer (NK) Cell
what is a lymphoid progenitor (aka lymphoblast)?
this is a precursor to other mature blood cell types such as T-lymphocytes, B-lymphocytes and Natural Killer cells
what is a natural killer cell?
a large granular lymphocyte
what type of microscope must be used to distinguish between different types of lymphocytes?
an electron microscope
where are B-cells conditioned (matured)?
in the Bone marrow
where are T-cells conditioned (matured)?
In the Thymus
what is the common progenitor cell that T and B cells share called?
It is called the small lymphocyte
what are B-lymphocytes responsible for?
Humoral immunity
what are the two cell types that B-cells can differentiate into once activated?
- Plasma cells
- Memory B-cells
what do plasma cells produce a lot of?
plasma cells produce a lot of antibodies
what do memory B-cells function as?
they function as immunological memory
how do antibodies travel?
antibodies travel via the body fluids such as blood, lymph and interstitial fluid
what are body fluids all known as?
body fluids are also known as the humours
what is the difference between humoral vs. cell mediated immunity
humoral immunity produces antigen specific antibodies and cell mediated immunity does not
what are T-cells responsible for?
Cellular immunity
what are the functions of T-helper cells?
- to respond to antigen presentation by “professional” cells.
- to help/mediate other leucocytes by secreting cytokines
what are examples of “professional” cells?
- B cells
- Macrophages
- Dendritic cells
what are examples of T-helper cells using cytokines on other leucocytes?
- T-helper cells activating B lymphocytes
- T-helper cells activate macrophages
- T-helper cells regulate T lymphocyte action
what is the function of T cytotoxic cells?
These cells respond to antigen presentation by “Non-professional” cells
what is an example of a T-cytotoxic cells function?
The T-cytotoxic cell’s response to any nucleated cell that has been infected or damaged
what are Natural Killer Cells a feature of?
innate (non-specific) immunity
what are the functions of Natural Killer cells?
- provide immune surveillance
- attracted by interferon-ɑ which is secreted by infected cells
- secrete interferon-𝛄 when they attack something to stimulate macrophages
what is immune surveillance?
it is when natural killer cells travel around tissues looking for cells with abnormal plasma membranes
How can NK cells kill infected cells?
By releasing perforins, which create a network of pores in the cell membrane of infected cells
how do perforins cause infected cell death?
they allow the free passage of ions, proteins and other intracellular material which the infected cell needs. This means the cell cannot maintain its internal environment.
Describe the steps for NK cells killing an abnormal cell.
- Recognition of abnormal cell and adhesion to cell
- Realignment of Golgi apparatus
- secretion of perforin
- Lysis of abnormal cell
what might a high count of lymphocytes indicate?
- Viral infection
- Some leukaemia
what might a low count of lymphocytes indicate?
- prolonged illness
- immunosuppression
- cortisol treatment
