Antigenic phenotype of TdT-positive cells in human peripheral blood.
Double immunofluorescence studies for terminal deoxynucleotidyl transferase (TdT) and leucocyte surface membrane antigens have been used to characterize the small subpopulation of TdT-positive cells in human peripheral blood. The predominant antigens demonstrated were those coded for by the major histocompatibility complex, namely HLA-A,B and Ia-like antigens. A small proportion of TdT+ cells expressed antigens restricted to B lymphocytes and their precursors (BA-1+ CALLA+). In contrast, antigens associated with T-lymphocyte differentiation were not detected using a panel of T-cell-specific monoclonal antibodies. These results preclude the possibility that circulating TdT+ cells are immature cortical thymocytes that have "leaked" into the bloodstream. Although bone marrow-derived prothymocytes, which have not yet acquired T-cell lineage markers, may be included amongst this subset, the expression of B-cell related antigens by some TdT+ cells indicates the likely existence of lineage heterogeneity amongst this population of lymphoid cells. The relevance of these findings to the monitoring of human acute lymphoblastic leukaemia is discussed.
Bradstock
K F
KF
Kerr
A
A
Bollum
F J
FJ
D000328:Adult; D000911:Antibodies, Monoclonal / Q000032:analysis; D000944:Antigens, Differentiation, B-Lymphocyte; D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D002454:Cell Differentiation; D002648:Child; D002675:Child, Preschool; D004253:DNA Nucleotidylexotransferase / Q000032:analysis*; D004254:DNA Nucleotidyltransferases / Q000032:analysis*; D005260:Female; D006649:Histocompatibility Antigens / Q000032:analysis; D006801:Humans; D008214:Lymphocytes / Q000145:classification / Q000201:enzymology* / Q000276:immunology; D008297:Male; D015260:Neprilysin
D000911:Antibodies, Monoclonal; D000944:Antigens, Differentiation, B-Lymphocyte; D000945:Antigens, Differentiation, T-Lymphocyte; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D006649:Histocompatibility Antigens; D004254:DNA Nucleotidyltransferases; D004253:DNA Nucleotidylexotransferase; D015260:Neprilysin