What are T-cells?

T-cells or T lymphocytes are a type of white blood cell that forms a key part of the adaptive immune system. They develop in the thymus gland. The ‘T’ is derived from its thymus-dependent development. 

T-cells play a pivotal role in protecting the body against infections by directly eliminating pathogens, killing infected host cells, and activating other immune cells while also coordinating immune responses. They also help the body fight harmful cells such as cancer cells. 

T-cells are largely categorized into cytotoxic T-cells, which directly kill infected or cancerous cells, and helper T-cells, which play a more supportive role in the immune system. 

Their ability to establish immunologic memory allows them to memorize the characteristics of the intruder in order to react faster and more potently to repeat encounters with the same pathogen, leading to longer lasting immunity against recurring infections.