Terminal deoxynucleotidyl transferase-positive B cell precursors in fetal lymph nodes and extrahemopoietic tissues.
Terminal deoxynucleotidyl transferase (TdT)-positive B cell precursors populate fetal lymph nodes (LN) of mid-term (16th-22th week) fetuses. These cells have a B cell phenotype (HLA-DR, CD45R, CD22, mu) and lack mature differentiation antigens (CD1c, CD20, L26). TdT+ cells are also present in the extranodal mesenteric mesenchyme, pancreas and LN primordia. Extranodal TdT+ cells are found among proliferating (i.e. Ki-67+) B cells and lack leukocyte function-associated antigen (LFA-1) and HLA-DQ; these latter molecules are acquired by nodal TdT+ elements. Adult LN, adult and fetal spleen contain less TdT+ cells than fetal LN. The fetal LN contains the full range of the B cell differentiation compartment, from the TdT+ precursor cell to the mature B lymphocyte.
Cattoretti
G
G
Division of Anatomic Pathology, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy.
Parravicini
C
C
Bonati
A
A
Buscaglia
M
M
Zuliani
G
G
Plebani
A
A
Delia
D
D
Rilke
F
F
D000954:Antigens, Surface / Q000032:analysis; D001402:B-Lymphocytes / Q000201:enzymology*; D004253:DNA Nucleotidylexotransferase / Q000032:analysis*; D005333:Fetus / Q000201:enzymology*; D006412:Hematopoietic Stem Cells / Q000201:enzymology*; D006801:Humans; D008198:Lymph Nodes / Q000201:enzymology*; D008213:Lymphocyte Activation; D010641:Phenotype; D013154:Spleen / Q000502:physiology
D000954:Antigens, Surface; D004253:DNA Nucleotidylexotransferase