Infection - Adaptive Immune Response Flashcards
Give some features of antigen presenting cells
- strategically located (skin, mucous membranes, lymphoid organs, blood circulation)
- pathogen capture (phagocytosis and macropinocytosis of soluble particles)
- diversity in pathogen sensors (can sense both extracellular and intracellular pathogens)
Where are dendritic cells found?
Lymph nodes, mucous membranes and blood
What do dendritic cells present antigens to?
Naive T-cells
Where are Lagerhans cells found?
Skin
What do Langerhans cells present antigens to?
Naive T cells
Where are macrophages found?
Various tissues
What do macrophages present antigens to?
Effector T cells
Where are B cells found?
Lymphoid tissues
What do B cells present antigens to?
Effector T cells and naive T cells
What are major histocompatibility complexes?
They hold the antigens that are presented to T cells
True or false - MHCs are only used in humoral immunity?
False - they are used in both humoral and cell-dependent immunity
What sort of MHC are HLA-A, HLA-B and HLA-C?
They are all class 1 molecules, found on all nucleated cells
What are HLA-DR, HLA-DQ and HLA-DP all examples of?
Class II molecules, found on dendritic cells, macrophages and B cells
Which type of MHC molecules present to intracellular pathogens?
Class I
What type of MHC molecule present to extracellular molecules?
Class II molecules
Give some key features of MHC class I and II molecules
- co-dominant expression (both parental genes expressed, meaning increased number of different MHC molecules)
- polymorphic genes (different alleles in different individuals increase presentation of different antigens)
What are intracellular microbes?
Viruses, some bacteria, protozoa
What are extracellular microbes?
Bacteria, parasites, worms, fungi
Where are T cells matured?
In the thymus
True or false - there are two types of CD4 cell that can be activated to counter extracellular microbes
True - TH2 and TH17. There is only one which can work against intracellular microbes - TH1
What are the roles of TH1 CD4+ cells?
- activate CD8 which activate cytotoxic T lymphocytes, which target infected cells via perforins and granzymes
- activate B cells which produce antibodies
- activate macrophages which work with antibodies to kill opsonised microbes
What are the roles of TH2 CD4+ cells?
- activate eosinophils which kill parasites
- activate B cells which produce antibodies
- activate mast cells which cause local inflammation and allergies
What is the role of TH17 cells?
Produce neutrophils which phagocytose other molecules
What is the difference between the primary and secondary antibody response?
Primary - mostly IgM produced, IgG builds up
Secondary - on secondary infection, less IgM is produced and far more IgG is made, which causes the secondary response to be faster, stronger, have a longer duration and a higher affinity.
