The hallmarks of adaptive immunity are specificity and memory.
Lymphocytes are the effectors of adaptive immunity. A lymphocyte has receptors on its surface of only one specificity - that is, it will respond to only one specific molecule or peptide. We have a huge repertoire of these lymphocytes, each with its own specificity. Thus, our lymphs can respond to many foreign molecules known as antigens or immunogens.
Once a specific lymphocyte recognizes its antigen, activation occurs, which results in clones of effector cells and some memory cells. Once the infection or threat is cleared, the effector cells will die off, but the memory cells will persist for years and sometimes decades. After that, the person will be "immune" to that specific pathogen. This is also the goal of vaccinations or immunizations - to elicit a memory response.
The topics covered in this section include:
- B lymphocytes and B lymphocyte receptors
- Development of B lymphocytes
- Function of B lymphocytes
- T lymphocytes and T lymphocyte receptors
- Development of T lymphocytes
- MHC antigens
- Function of T lymphocytes
