lymfopoese

Lymfopoese, or lymphopoiesis, is the development and maturation of lymphocytes, a set of white blood cells essential to adaptive and innate immunity. It includes the formation of B cells, T cells, and natural killer (NK) cells from hematopoietic stem cells. In humans, most B cell and NK cell precursors develop in the bone marrow, while T cells complete their maturation in the thymus; during fetal life, other organs such as the fetal liver can contribute to early lymphoid development.

The process begins with hematopoietic stem cells differentiating into common lymphoid progenitors (CLP). CLPs can commit to the B cell, T cell, or NK cell lineages. B cells mature primarily in the bone marrow, where immunoglobulin genes rearrange to form the B cell receptor. T cells migrate to the thymus, where thymocytes undergo rearrangements of their T cell receptor genes and progress through stages from double-negative to double-positive, then single-positive cells, under selection processes that test for self-tolerance and adequate MHC recognition. NK cells arise mainly from CLPs and mature in the bone marrow and peripheral tissues, acquiring their cytotoxic and cytokine-producing capabilities, with development influenced by cytokines such as IL-15.

Regulation of lymfopoese involves cytokines (notably IL-7 for B and T cells and IL-15 for NK cells), transcription factors (for example, E2A, EBF1, and PAX5 for B cells; Notch signaling, TCF-1, GATA3, and Bcl11b for T cells), and cellular microenvironments. Lymfopoese is an ongoing process that can be affected by aging, infection, or hematopoietic disorders, and it underpins the body’s capacity to mount adaptive and innate immune responses.