T lymphocyte characteristics in bone marrow-transplanted patients. I. Changes in biochemical properties that correlate with the immunologic reconstitution.

Abstract

Abstract Twelve patients with severe aplastic anemia were successfully reconstituted by allogeneic bone marrow transplantation. Shortly after bone marrow transplantation, all patients developed a severe cellular immunodeficiency, with low numbers of T lymphocytes and depressed responsiveness to mitogens (PHA, ALS, Con A, PWM) and to allogeneic lymphocytes. The immunodeficiency varied considerably from patient to patient, not only with regard to severity and duration, but also with regard to the kinetics of recovery of lymphocyte proliferative responses. To further characterize the peripheral T lymphocytes obtained from the patients during the severe cellular immunodeficiency, we analyzed the binding capacity for peanut lectin, the iso-enzyme pattern of lactate dehydrogenase, the activities of ecto-5’-nucleotidase and of purine nucleoside Phosphorylase, and the relative number of Tμ and Tγ cells. The results were compared with the marker profile of peripheral T lymphocytes from normal healthy donors and with thymocytes. With all parameters investigated, a marked difference was found between T lymphocytes from normal donors and thymocytes. T lymphocytes obtained from patients during severe cellular immunodeficiency resembled thymocytes in binding of peanut lectin, in lactate dehydrogenase pattern, and in activity of ecto-5’-nucleotide. Moreover, during this period, the patients had low numbers of Tμ cells. T lymphocytes obtained from patients either before bone marrow transplantation or after complete normalization of the immune functions did not differ biochemically from normal T lymphocytes. In some cases, it was possible to study T lymphocytes of the same patient before bone marrow transplantation, during severe cellular immunodeficiency, and after normalization of the immune functions. In those cases we found normal lymphocytic markers in peripheral T cells before bone marrow transplantation and after normalization of the immune functions, but thymocyte-like properties during immunodeficiency. We conclude that a close correlation exists between the lack of lymphocyte reactivity to mitogens and allogeneic lymphocytes, and a particular pattern of the parameters evaluated. The presence in peripheral blood of T lymphocytes with this particular pattern may reflect either the predominant presence of immature T lymphocytes or of a given T cell subset, normally present in low amounts.