CD7-positive acute leukemia lacking T cell receptor gene rearrangements and terminal deoxynucleotidyl transferase expression suggesting pre-T cell origin.
In this report, we describe a case of acute leukemia possessing a unique immunophenotype. Leukemic cells isolated from peripheral blood were analyzed by automated fluorescence-activated flow cytometry. They demonstrated the following antigen pattern: CD7+, CD38+, transferrin receptor+, HLA-DR+, common ALL antigen (CALLA)-, and terminal deoxynucleotidyl transferase (TdT)-. No expression of B cell or myeloid antigens was observed. The observed antigen pattern suggests a pre-T cell origin. In addition, the tumor cells contained germline T cell receptor beta (T beta) and gamma (T gamma) chain genes, and a germline immunoglobulin heavy chain (JH) gene. These findings support the concept that pre-T cell leukemias may demonstrate germline T beta and T gamma genes as well as lack TdT expression. In addition, our results suggest that CD7 expression may be one of the earliest events in T cell differentiation, occurring prior to both T beta an T gamma gene rearrangements, and TdT expression.
Jacobs
J C
JC
Department of Pathology, University of California, San Diego Medical Center 92103-1990.
Rearden
A
A
D000208:Acute Disease; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D015139:Blotting, Southern; D002460:Cell Line; D004253:DNA Nucleotidylexotransferase / Q000378:metabolism*; D005260:Female; D015329:Gene Rearrangement, T-Lymphocyte; D006801:Humans; D007158:Immunologic Techniques; D007938:Leukemia / Q000201:enzymology / Q000235:genetics* / Q000276:immunology; D008875:Middle Aged; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*
D000945:Antigens, Differentiation, T-Lymphocyte; D011948:Receptors, Antigen, T-Cell; D004253:DNA Nucleotidylexotransferase