IMMUNOLOGY

Detailed explanation-1: -T lymphocytes develop from a common lymphoid progenitor in the bone marrow that also gives rise to B lymphocytes, but those progeny destined to give rise to T cells leave the bone marrow and migrate to the thymus (see Fig. 7.2). This is the reason they are called thymus-dependent (T) lymphocytes or T cells.

Detailed explanation-2: -T cells are part of the immune system and develop from stem cells in the bone marrow. They help protect the body from infection and may help fight cancer.

Detailed explanation-3: -Bone marrow T cells exert potent antigen-specific effector function, as demonstrated by either adoptive transfers in immunodeficient mice (5) or in vitro studies (7). T cells from BM of patients with different types of solid and hematological cancers were able to kill autologous tumor cells (40, 71, 72).

Detailed explanation-4: -Both B and T lymphocytes originate in the bone marrow but only B lymphocytes mature there; T lymphocytes migrate to the thymus to undergo their maturation. Thus B lymphocytes are so-called because they are bone marrow derived, and T lymphocytes because they are thymus derived.

Detailed explanation-5: -It is true that B cells and T cells are formed in the bone marrow. B cells secrete antibodies through humoral response, which is an important component of adaptive immune system. T cells mature in the thymus and are critical components of the cell mediated immune response, which is also part of adaptive immunity.

Detailed explanation-6: -All T cells originate from c-kit+Sca1+ haematopoietic stem cells (HSC) which reside in the bone marrow. In some cases, the origin might be the fetal liver during embryonic development. The HSC then differentiate into multipotent progenitors (MPP) which retain the potential to become both myeloid and lymphoid cells.