Solitary Expression of CD7 Among T-Cell Antigens in Acute Myeloid Leukemia: Identification of a Group of Patients With Similar T-Cell Receptor β and δ Rearrangements and Course of Disease Suggestive of Poor Prognosis

In a series of 100 acute myeloid leukemia (AML) patients defined by cytochemistry and immunophenotyping, 20 expressed T-lymphocyte associated antigens on the surface of their blasts. While 15 expressed two or more T-cell antigens, five were found to express only CD7. All patients belonged to the French-American-British type M4, and four were under the age of 40. Despite intensive chemotherapy, four never obtained a complete remission and the fifth died of relapse after an allogenic bone marrow transplantation. While 12 randomly selected T-cell antigen negative AML patients showed only few rearrangements in Igor T-cell receptor (TCR) genes, such genetic alterations were demonstrated in four of five patients for the TCR δ gene and in all patients for the TCR β gene. Interestingly, DNA fragments of similar size were demonstrated in three of five patients for both the β and δ genes. These data suggest that the solitary presence of CD7 among T-cell antigens in otherwise clearcut AML cases identifies a group of patients with similarities in antigen receptor gene configuration as well as outcome.