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| Antibodies |
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| An antibody is a protein produced by the body in response to the presence of an antigen. Anti bodies belong to a group of proteins called globulins and they are also known as Immunoglobulins (Ig). |
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| Adaptive Immunity has the following features: |
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| 1) Specificity |
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| It is the ability to distinguish differences among various foreign molecules. |
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| 2) Diversity |
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| It can recognise a vast variety of foreign molecules. |
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| 3) Discrimination between self and non-self |
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| It can recognise and respond to molecules that are foreign or 'non-self'. It can also avoid response to molecules that are part of the body or 'self' of the animal |
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| 4) Memory |
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| When the immune system encounters a specific foreign body namely a microbe, for the first time, it generates immune responses and eliminates the invading organism. The system retains the memory. When a second encounter with the same group of microbe occurs, the memory helps in producing greater and quicker immune response. |
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| Specific immunity uses 2 groups of cells (1) Lymphocytes (2) Antigen presenting cells. |
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| A healthy man has about one trillion lymphocytes. Lymphocytes may be distinguished into 2 kinds, namely T-cells or T-lymphocytes and |
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| B-cells or B lymphocytes. T cells are responsible for cellular immunity. B cells provide humoral immunity. Both the types are produced in bone marrow. The process of their production is called Haematopoiesis. Some immature lymphocytes first migrate to the thymus gland, where they mature to become T-Cells. As their maturation occurs in Thymus gland, they are called T cells. The rest of the lymphocytes, which mature in the bone marrow itself are called B cells. |
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| Both B-cells and T-cells are responsible for 2 types of specific immunity: |
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| (a) Cell - mediated Immunity and (b) Anti-body mediated Immunity. |
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| Our immune system can recognise a large variety of antigens. The sites on antigens that are recognised by the antibodies are called Antigenic determinants. The receptors of T and B-cells also recognise these sites. |
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| Adaptive immunity can be either active or passive. |
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| Formation of B-lymphocytes and T-lymphocytes and thier action in the immune response |
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