Lymphoid cell development

Normal Lymphoid Cell Development and Antigen Expression. 303... 

A variety of type 2 cytokines and the non-lymphoid cell-derived growth factor, stem cell factor (SCF) (Hiiltner et al., 1989 Copeland et al., 1990 Huang et al., 1990 Thompson-Snipes et al., 1991 reviewed in Befus, 1995), are known to be important in the development of intestinal mast cell responses associated with nematode infection but the contribution of this population to host protection depends on the nematode species in question. 

Lymphoid neoplasms are clone-expanded proliferations of cells representing distinct stages of B/T cell development. Immunoglobulin gene rearrangements can be detected to indicate monoclonality of B-cell lineage lymphoproliferative... 

Both the B cells and T cells arise in the fetal liver or bone marrow (Fig. 31-1) from pluripotent stem cells. In birds the B cells develop in a special organ, the bursa of Fabricius. Mammalian B cells complete their differentiation into mature lymphocytes within the bone marrow. However, the T cells must travel to the thymus, where they complete their maturation. The T lymphocytes include the previously mentioned NK cells as well as the somewhat similar cytolytic T cells and immunoregulatory T cells. The latter are further characterized as helper T cells41 or suppressor T cells. The adaptive response requires cooperation of helper T cells in many instances. Tire mature B and T cells leave the bone marrow and thymus, which are known as the primary lymphoid tissues, and enter the blood circulation. Following "homing" signals42 they take up residence in a variety of locations... 

There are three different kinds of lymphocytes that have specific functions T cells, B cells and NK cells. T cells develop in the thymus while B cells develop in the adult bone marrow. The thymus and the bone marrow are the primary lymphoid organs where lymphocytes acquire specific cell surface receptors that give them the ability to recognize antigens. NK cells are cytotoxic lymphocytes that develop in the bone marrow. The phagocytes are made up of either monocytes (macrophages) or polymorphonuclear granulocytes, which include neutrophils, eosinophils and basophils. 

Lymphocytes are one of the primary cell types involved in the immune response. There are two general types of lymphocytes, B and T. Both are derived from bone marrow lymphoid stem cells, but T cells go through an additional maturation process in the thymus. Although the morphology of T cells and B cells is similar, the functions of these two types are distinct. After antigen exposure, B cells develop into antibody-producing plasma cells, whereas T cells are divided into functional subtypes that possess distinct cell surface antigens. 

L., and Handgretinger, R (2005). Htnnan lymphoid and myeloid cell development in NOD/LtSz-.va d IL2rq nul1 mice engrafted with mobilized htnnan hematopoietic stem cell. J. Immunol. 174 6477-6489. 

T cell development, similar to B cell ontogeny, can also be divided into stages based on antigen expression (Table 4) extrathymic precursor, prothymocyte, immature thymocyte, common thymocyte, mature thymocyte, and mature peripheral T cell. However, while the early stages of T cell development are well characterized, the later stages of T cell differentiation, that is, those of the mature peripheral T cell, have not been fully delineated (C3, F12, H13, K15, K16, K20, R6-R8,V3, V4). Furthermore, although natural killer (NK) cells are closely related to T cells (S21), the stages of differentiation of this lymphoid cell population are not completely understood. 

Rooney A, Fournier M, Bernier J, Cyr D (2003) Neonatal exposure to propylthiouracil induces a shift in lymphoid cell sub-populations in the developing postnatal male rat spleen and thymus. Cell Immunol, 223 91-102. 

Blom B, Spits H (2006) Development of human lymphoid cells. Annu Rev hnmun 24 287—320. 

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