T cells are generated in the Thymus and are programmed to be specific for one particular foreign particle (antigen). Once they leave the thymus, they circulate throughout the body until they recognise their antigen on the surface of antigen presenting cells (APCs).

Where do T cells proliferate and mature?

T cells are born from hematopoietic stem cells, found in the bone marrow. Developing T cells then migrate to the thymus gland to mature. T cells derive their name from this organ where they develop (or mature).

Do T cells proliferate in response to infection?

For example, viral infection causes clonal expansion of antigen-specific CD8 T cells, during which peripheral CD8 T cells massively expand and up to ~90% of the total CD8 T cells may become antigen specific in case of lymphocytic choriomeningitis virus infection (7).