Adaptive Immunity:
The adaptive immune system is the part of the immune system that can specifically target pathogens. It also stores immunological memory. This memory means that when a pathogen is encountered a second time, the response will be quicker and more effective. This memory can be stored in different types of B-cells and T-cells. There are two types of adaptive immunity: cellular and humoral.
B-cells: They are immune cells that mature in the bone marrow. They are involved in humoral immunity. When they encounter an antigen (substances that can cause a adaptive immune response), the cells divide into plasma cells, which produce antibodies and into memory cells which store memory in case of a second exposure.
T-cells: They are immune cells that mature in the thymus. They are involved in cellular immunity. There are four types. The helper T-cells help activate other T-cells and B-cells. Cytotoxic T-cells kill virally infected cells or cancerous cells. They act like natural killer cells. They also use perforins and granzymes. Memory T-cells have the same function as memory B-cells. They store immunological memory in case of a second exposure. Regulatory or Suppressor T-cells are the cells that stop the immune response. This prevents the immune system from going crazy.
You may have heard me mention the word antibody. Antibodies are Y-shaped proteins that bind to a specific antigen. They all have a variable portion that is different among every plasma B-cell. This helps the immune system to be more versatile and a more variety of pathogens that they can kill. Antibodies fight infection in four ways: Complement fixation and activation, Agglutination, Neutralization, and Precipitation. Complement fixation and activation helps activate the complement (self explanatory). This means that they help with phagocytosis (adherence specifically). Neutralization occurs when antibodies block specific site on bacteria or viruses which cause them to be inactive. Agglutination occurs when antigens clump together which also makes adherence easier for phagocytes. Precipitation is the same as agglutination, but with free-floating antigens not with cells.
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