Cells Involved in Immune Response Flashcards
Neutrophils - function
- First life of defence against all infections
- Primary phagocytic cell of innate immunity
- Phagocytose invading organisms
- Present antigens to immune system
- Release cytokines
What are the granulocytes? What are they characterised by?
Neutrophils, eosinophils, basophils
Multilobed (2-5) nuclei, granules in cytoplasms
Eosinophils - function
- Specifically act against multicellular parasites
- Involved in IgE mediated allergic disorders
- Release cytokines
Basophils - function
Important role in allergic reactions through binding with IgE antibodies to release histamine
Monocytes - function
Produced in bone marrow and travel in blood to target tissues to become macrophages
- Phagocytosis
- Antigen presentation
- Cytokine production
Monocytes - structure
Largest type of leukocyte (WBC)
- Bean shaped nuclei
- Precursor of tissue macrophages
What are macrophages derived from?
Derived from blood monocytes which differentiate once they reach target tissues
Why are macrophages not found on a full blood count?
Tissue cells
Macrophages - function
- ‘Tidy up’ pathogens, foreign debris and old/dead cells by phagocytosis
- Antigen presentation
- Can activate memory cells
- Participate in innate and adaptive immunity
How are macrophages controlled?
- Only phagocytose dying cells
2. Only phagocytose opsonised cells and pathogens
How do macrophages only phagocytose dying cells?
Membrane plasma lipid profile changes when a cell dies - macrophages recognise this
How do macrophages only recognise opsonised cells and pathogens?
Surface is coated with with complement proteins/antibodies so can be taken up by Fc receptor on macrophages
Dendritic cells - function
Formed in bone marrow and circulate in blood until they reach target tissues
- Phagocytose pathogens before migrating to lymph nodes where they present antigens on cell surface to activate adaptive immunity
- Main ‘professional’ antigen presenting cells
- Activate T helper and memory cells
What happens when dendritic cells reach target tissues?
Activated by pathogens and differentiate into mature forms
Dendritic cells have specialised receptors on surface. What does this enable?
Allows it to recognise patterns of foreign molecules (e.g. clusters of sugars)
What happens when dendritic cells present antigen to naive T cell?
- T cell can proliferate
- Daughter T cells stimulate B cells to mature and produce antibodies
- Antibodies coat pathogens that macrophages can phagocytose them (opsonisation)
Can macrophages present to naive T cells?
No but they can present to primed daughter T cells activated by dendritic cell
What are the lymphocytes?
B cells, T cells, NK cells
B cells - function
- Produce antibodies after maturation
- Present antigens
- Produce memory cells
- Essential for humoral immunity (antibody-mediated response)
T cells - function
- Essential for cell mediated immunity
- Influences other cells
- Can kill virally infected and tumour cells
- Generate long lived memory cells
NK cells - structure
Large and granular lymphocytes
NK cells - function
- Innate and adaptive immunity
- Destroy pathogens and infected cells without need for prior activation
- Viral immunity and tumour rejection
- Trigger apoptosis in target cells (can kill infected cells that don’t express foreign surface antigen)
