IMMUNOLOGY

Detailed explanation-1: -Recent experiments show that CD4 cells can differentiate into two types of memory cell, with distinct activation characteristics. One type are called effector memory cells because they can rapidly mature into effector CD4 T cells and secrete large amounts of IFN-, IL-4, and IL-5 early after restimulation.

Detailed explanation-2: -Once the immune response is complete, many of these cells die by apoptosis restoring the immune response to its original size-with one major change. Some of the B and T cells become memory cells, which are basically a pool of lymphocytes that are all set to combat the pathogen, if they encounter it again!

Detailed explanation-3: -T cells are a part of the immune system that focuses on specific foreign particles. Rather than generically attack any antigens, T cells circulate until they encounter their specific antigen. As such, T cells play a critical part in immunity to foreign substances.

Detailed explanation-4: -Adaptive immune responses depend on the ability to recognize and eliminate recurrent pathogens, resulting in the generation of memory lymphocytes. The capacity of memory T cells to rapidly mobilize and initiate a potent recall response enhances protective immunity against previously encountered pathogens.

Detailed explanation-5: -Memory T cells are established at both lymphoid and peripheral sites following the clearance of an invading pathogen.