immune_memory_flashcards
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What is immune memory?
Feature of adaptive immune system - pool of antigen specific cells following infection with enhanced ability to respond to a second infection.
What cells are involved in presenting peptides to T lymphocytes to initiate an acquired immune response?
Antigen presenting cells (APCs - macrophages, B lymphocytes, Langerhans cells, dendritic cells).
What are the markers for memory T cells and naïve T cells?
CD45 RO = memory T cells, CD45 RA = naïve T cells.
How long do memory cells remain following an infection?
Memory cells remain for a long time following infection.
Do memory cells continue to proliferate after infection?
Yes, they continue to proliferate at a low rate.
What is the response of memory cells to subsequent exposure to an antigen?
Rapid and robust response, easier to activate than naïve cells.
What influences the migration and adhesion of memory T cells?
Different cell surface markers.
Can memory T cells access non-lymphoid tissue?
Yes, they can access non-lymphoid tissue (the sites of microbe entry).
Where are central memory cells found?
In lymph nodes & tonsils - roll along and extravasate in High Endothelial Venules (HEVs).
Where are effector memory cells found?
In liver, lungs, and gut.
What markers do central memory cells express?
CCR7+ and CD62L high (allow entry/migrate via HEVs to peripheral lymph nodes).
What markers do effector memory cells express?
CCR7-ve and CD62L low (therefore not found in lymph nodes).
What do central memory cells produce?
IL-2 (to support other cells).
What do effector memory cells produce?
Perforin and IFN-γ.
Which population has more central memory cells, CD4 or CD8?
More central memory in CD4 population.
Which population has more effector memory cells, CD4 or CD8?
More effector memory in CD8 population.
Describe the process of immune memory development after exposure to a pathogen.
Exposure to pathogen → Antigen(s) stimulation of specific T and B lymphocytes → Expansion → Some lymphocytes become effector cells and some become memory cells → Immunologic memory develops (long lived, up to 65 years).
What are the steps involved in the expansion of specific T and B lymphocytes?
Antigen stimulation of specific T and B lymphocytes leads to their expansion.
What do some lymphocytes become after the expansion?
Effector cells and memory cells.
What type of immunoglobulins do B cells produce in the memory response?
IgG and some IgM.
What happens to B cells stimulated by an antigen?
Expansion/isotype switching (due to cytokines provided by T helper cells) → Plasma cells producing antibody/memory cells.
What type of cells can memory B cells differentiate into?
Memory cells that can differentiate into plasma cells (long lived).
What is the response of memory B cells compared to the first exposure?
Quicker response, more antibodies, higher affinity antibodies, more IgG, and generally better antibodies.
Describe the Mantoux Test procedure.
Inject 0.1 ml of 5 tuberculin (purified protein derivative) units intradermally, examine arm 48-72 hrs after.
What indicates a positive Mantoux Test result?
Induration (swelling that can be felt) of at least 10 mm in diameter (erythema around not measured).
What does a positive Mantoux Test imply?
Previous exposure to tuberculin protein, which could represent previous BCG exposure.
