Tutorial 1 Flashcards
What is clonal selection?
Many antigen specific receptors are created with many different specificities on their surface.
When one of these diverse receptors comes into contact with respective antigen it replicates very quickly.
Immune response becomes tailored to the new antigen
What is memory?
Memory is the ability to create memory cells that respond more rapidly in secondary immune response due to presence of long-lived memory cells.
What are naïve lymphocytes?
Cells with receptors for antigens that have never encountered an antigen before.
What is the antibody response like in secondary response?
Much higher and more specific than the first response.
What is clonal expansion?
Increase in number of antigen-specific lymphocytes to keep pace with the microbes
What is contraction and homeostasis?
A decrease in number of immune cells to respond appropriately to the decrease in pathogens that were encountered. (i.e post disease recovery)
What is specialization?
Response is optimal for defence against different types of microbes.
What are the cells that initiate T cell response?
Dendritic cells
What is the effector phase of cell-mediated immunity?
Macrophages
What do follicular dendritic cells do?
Display antigens to B lymphocytes in humoral immune response
How are antigens eliminated?
T lymphocyte cytotoxicity
Monocytes and macrophages through phagocytosis
Granulocytes: neutrophils and eosinphils
What do helper T cells do?
They recognize pathogenic antigens and respond by releasing cytokines which stimulate activation of macrophages, inflammation, and activation of T and B lymphocytes
What do cytotoxic T lymphocytes do?
They recognize intracellular antigens by recognizing peptides bound to MHC molecules
What do regulatory T lymphocytes?
They limit activation of other lymphocytes especially T cells to prevent autoimmunity from occuring
What do NK cells do?
Recognize infected self cells and destroy them
Where do lymphocytes develop?
Common lymphoid precursors develop into mature forms in the bone marrow (for B cells) and thymus (for T cells)
What happens to naïve lymphocytes after interacting with foreign antigens?
Naïve lymphocytes recognize microbial antigens and differentiate and proliferate into effector lymphocytes after the appropriate additional signals are given to them
What do effector cells do?
Effector cells function to eliminate antigens. B cells are antibody secreting. CD4 lineage produce cytokines and CD8 cells are cytotoxic
What else do effector cells differentiate into?
Memory lymphocytes
Where do memory T cells migrate after differentiation?
Typically they are heterogenous with one subset that goes to lymph nodes, one subset to mucosa, and one subset to inflamed tissues
Where do effector lymphocytes go after differentiation and proliferation?
Inflamed tissues preferentially
Where do Naïve cells migrate after they are formed?
Peripheral lymph nodes
What types of antibodies are produced by Naïve cells?
IgM and IgD
What types of antibodies are produced by effector B cells?
IgG IgA and IgE
What antibodies are produced by memory lymphocytes?
IgG IgA IgE
What is the affinity of IgM and IgD produced by naive B cells?
Relatively low
What is the affinity of IgG IgA and IgE antibodies produced by effector B cells like?
Increases during immune response
What is the affinity of IgG IgA and IgE produced by memory B cells like?
Relatively high
What kind of cells can be found in skin?
Antigen presenting cells
What is the section of the spleen surrounded in and why?
Periartiolar lymphoid sheath (PALS) and attached follicle containing a prominent germinal center. PALS and lymphoid follicles constitute white pulp.
Where are cutaneous and mucosal immune systems located?
Cutaneos immune system is in and under epithelia of the skin
Mucosal is in under GI and resp tract
Where are most of the body’s lymphocytes located?
1/4 are in mucosal tissues and skin - many are memory cells
What do M cells?
prevent transport of antigens from lumen
What antibody is abundant in mucosal tissue?
IgA
What WBCs are present in lamina propria of GI tract?
dendritic cells
macrophages
T lymphocytes provide adaptive immune defence
What prevents commensal bacteria from entering into the lamina propria?
The mucous
Where do B cells reside in peripheral lymphoid organs?
In follicles
Where do T cells reside in peripheral lymphoid organs?
In periartiolar lymphoid sheaths (PALS)
How is organization of lymphoid organs regulated?
Chemokines;
How are B cells brought into the follicles?
B cells are attracted to follicles by the production of a chemokine that interacts with CXCR5
How are T cells brought into the PALS?
chemokines that interact with CCR7
Where do naïve T cells migrate when they enter circulation?
to LNs where they find epithelial and parenchymal antigens.
How do Naïve T cells enter Lymph Nodes?
Through specialized postcapillary high endothelial venules
Does the spleen have high endothelial venules? Does it have naïve lymphocytes?
No HEVs but the pattern of lymphocyte migration is similar
How is the encounter between T cell and antigen containing (?DC?) cell carried out?
completely randomly because most naïve T cells circulate each lymph node at least once per day
What happens if naïve T lymphocyte does not interact with a new pathogen?
It reenters the circulation
How do dendritic cells enter and where do they migrate?
Through the afferent lymphatic vessels and they migrate in response to chemokines they pick up antigens from epithelium and migrate to T cell rich areas
Where do activated T cells go after they have been activated?
to sites of inflammation and infection
