• Non-Specific - response is immediate and the same for all pathogens
• Physicial Barrier (e.g. skin)
• Phagocytosis

• Specific - response is slower and specific to each pathogen
• Cell medidated response (T cells)
• Humoral response (B cells)

• When it comes to IBDP Biology, any part of an organism or substance which is foreign (non self), and stimulates an immune response. 
• They are usually proteins which usually are on the cell surface membranes of pathogens.
• Antigens are not always on the invading cell. You can have antigen-presenting cells which are cells from the immune system which take the pathogen's antigens and allow the functions of the immune system to work. 

When it comes to IBDP Biology, lymphocytes are white blood cells. There are two types of lymphocytes:

• T lymphocytes (T cells)

- mature in the thymus gland

- associated with cell mediated immunity

• B lymphocytes (B cells)

- mature in the bone marrow 

- associated with humoral immunity 

In IBDP Biology,

• Cell mediated immunity- immunity with body cells involving T cells
• Humoral immunity- immunity with bodily fluids involving B cells

This is the end of this topic

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