| Term 
 | Definition 
 
        | a specific immune response |  | 
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        | Term 
 | Definition 
 
        | from stem cells in the bone marrow |  | 
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        | Term 
 | Definition 
 
        | the tymus gland and develop into T Lymphocytes (T cells) |  | 
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        | Term 
 
        | Lymphocytes that remain in the |  | Definition 
 
        | bone marrow develop into B lymphocytes (B cells) |  | 
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        | Term 
 | Definition 
 
        | any foreign molecule that is recognised by a lymphocytes eg. Viruses, bacteria |  | 
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        | Term 
 
        | Lymphocytes have a single type of |  | Definition 
 
        | membrane receptor which is specific for only one type of antigen |  | 
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        | Term 
 
        | A lymphocyte is said to have been “selected” |  | Definition 
 
        | when it is activated by a specific antigen |  | 
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        | Term 
 
        | A person’s antigen signature is |  | Definition 
 
        | the unique combination of cell surface proteins on the body cells’ surface |  | 
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        | Term 
 
        | The antigen signature is critical as it ensures |  | Definition 
 
        | the person’s own lymphocytes do not try to destroy their own body cells surface proteins |  | 
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        | Term 
 
        | During maturation of B and T cells |  | Definition 
 
        | any lymphocytes bearing an antigen receptor that fits a body cell surface protein is destroyed |  | 
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        | Term 
 
        | Auto-immunity is when T lymphocytes launch an attack on |  | Definition 
 
        | The body’s own cells and it is the cause of auto-immune diseases eg. Rheumatoid arthritis, Type 1 diabetes, MS |  | 
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        | Term 
 
        | An allergic reaction is caused by |  | Definition 
 
        | Hypersensitive B lymphocytes responding to harmless substances (eg. Pollen, dust, feathers) |  | 
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        | Term 
 
        | The two groups of T lymphocytes are |  | Definition 
 
        | Helper T cells and Cytotoxic (killer) T cells |  | 
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        | Term 
 | Definition 
 
        | secrete cytokines to activate phagocytes, T cells and B cells |  | 
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        | Term 
 | Definition 
 
        | destroy infected cells by apoptosis |  | 
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        | Term 
 
        | Antigen presenting cells are |  | Definition 
 
        | phagocytes which capture the pathogen and display fragments of the antigen on their surface |  | 
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        | Term 
 
        | Antigen presenting cells activate the |  | Definition 
 
        | production of a clone of Helper T cell Lymphocytes that move to the site of infection secreting cytokines |  | 
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        | Term 
 
        | Each B lymphocyte clone produces |  | Definition 
 
        | a specific antibody molecule that will recognise a specific antigen surface molecule on a pathogen or toxin |  | 
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        | Term 
 
        | Antigen-antibody complexes may |  | Definition 
 
        | inactivate a pathogen/toxin or render it more susceptible to phagocytosis or bring about cell lysis |  | 
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        | Term 
 
        | Antibodies are secreted into |  | Definition 
 
        | the blood and lymph where they make their way to the infected area |  | 
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        | Term 
 
        | Some T and B lymphocytes produced by clonal selection |  | Definition 
 
        | survive long term as memory cells |  | 
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        | Term 
 
        | Secondary exposure to the same antigen |  | Definition 
 
        | rapidly gives rise to a new clone of lymphocytes producing a rapid and greater immunological response |  | 
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