Adaptive Immunity is the third line of defense that make plasma and memory cells.
• Adaptive immunity depends on two types of lymphocytes that recognize and respond to specific invading pathogens.
• Like all blood cells, lymphocytes originate from stem cells in the bone marrow.
B cells fully develop and become specialized in the bone marrow.
Immature T cells migrate via the blood to the thymus, a gland in the chest, where they mature and become specialized.
Both B cells and T cells eventually make their way to the lymph nodes and other lymphatic organs and wait to encounter an invader.