Antibody-Mediated Immunity

• Involves the production and release of antibodies into the blood and lymph.
• Lymphoid tissue contains thousands of B-cells with each having a receptor for a particular antigen.
• Antigen-presenting cells present the antigens to specific B-cells which become activated.
• Antigen-presenting cells also present to helper T-cells that release cytokines which also activates B-cells.
• B-cells enlarge and divide into clones becoming either plasma cells or memory cells.
• Plasma cells secrete specific antibodies capable of attaching to antigen active sites.
• The antibodies secreted by B-cells circulate in the blood, lymph and extracellular fluid to reach sites of invasion.
• On first exposure to an antigen the body's immune system responds fairly slowly because it takes time for B-cells to multiply.
• On second exposure to the same antigen the response is much quicker due to memory cells.
• In the secondary response plasma cells can form quicker and antibody levels in the blood rise rapidly to a higher level.
• Provides resistance to micro-organisms before they enter the body's cells.